STUDIES ON FOOT ROT OF BLACK PEPPER CAUSED BY Phytophthora capsici Leonian, emend, Alizedeh

and Tsao.

Thesis submitted to the University of Agricultural Sciences, Dharwad

in partial fulfillment of the requirements for the

Degree of

MASTER OF SCIENCE (AGRICULTURE)

In

PLANT PATHOLOGY

By

SHASHIDHARA S.

DEPARTMENT OF PLANT PATHOLOGY COLLEGE OF AGRICULTURE, DHARWAD

UNIVERSITY OF AGRICULTURAL SCIENCES, DHARWAD - 580 005

NOVEMBER, 2007

ADVISORY COMMITTEE

DHARWAD (M. S. LOKESH) NOVEMBER, 2007 MAJOR ADVISOR

Approved by :

Chairman : ___________________________ (M. S. LOKESH)

Members : 1. _________________________ (M. G. PALAKSHAPPA)

2. _________________________ (S. LINGARAJU)

3. _________________________ (R. V. HEGDE)

C O N T E N T S

Sl. No. Chapter Particulars

CERTIFICATE

ACKNOWLEDGEMENT

LIST OF TABLES

LIST OF FIGURES

LIST OF PLATES

1 INTRODUCTION

2 REVIEW OF LITERATURE

2.1 History and distribution

2.2 Economic importance

2.3 Symptomatology

2.4 Isolation and proving pathogenicity

2.5 Biological control

2.6 Effect of plant extracts

2.7 Chemical control

2.8 Host plant resistance

2.9 Integrated management

3 MATERIAL AND METHODS

3.1 Survey for disease incidence, isolation and proving pathogenicity

3.2 Isolation and evaluation of native antagonistic microorganisms

3.3 In vitro evaluation of botanicals and fungicides against Phytophthora capsici

3.4 Screening of seedlings of cultivated black pepper varieties

3.5 Integrated management of Phytophthora foot rot of black pepper

Contd…..

Sl. No. Chapter Particulars

4 EXPERIMENTAL RESULTS

4.1 Survey for the incidence and distribution of foot rot of black pepper

4.2 Symptomatology

4.3 Isolation

4.4 Isolation and in vitro evaluation of native antagonistic microorganisms

4.5 In vitro evaluation of botanicals and fungicides on Phytophthora capsici

4.6 Screening of black pepper seedlings against Phytophthora capsici

4.7 Integrated management Phytophthora foot rot of black pepper

5 DISCUSSION

5.1 Survey for the disease incidence, isolation of Phytophthora capsici and proving its pathogencity

5.2 Isolation of native antagonistic microorganisms and their in vitro evaluation against P. capsici

5.3 In vitro evaluation of botanicals and fungicides against P. capsici

5.4 Screening of black pepper varieties against Phytophthora capsici

5.5 Integrated management of Phytophthora foot rot of black pepper

6 SUMMARY AND CONCLUSIONS

REFERENCES

ABSTRACT

LIST OF TABLES

Table No.

Title

1 Incidence of Phytophthora foot rot of black pepper during pre-monsoon season (May-June) 2006-07

2 Incidence of Phytophthora foot rot of black pepper during peak-monsoon season (July-August) 2006-07

3 Incidence of Phytophthora foot rot of black pepper during Post-monsoon season (October-November) 2006-07

4 In vitro evaluation of native microbial antagonists against Phytophthora capsici

5 In vitro evaluation of plant extracts against Phytophthora capsici

6 Bioassay of fungicides against Phytophthora capsici causing foot rot of black pepper

7 Screening of black pepper varieties against Phytophthora capsici

8 Incidence of leaf infection (%) in integrated management of Phytophthora foot rot of black pepper

9 Incidence of yellowing index (%) in integrated management of Phytophthora foot rot of black pepper

10 Incidence of defoliation index (%) in integrated management of Phytophthora foot rot of black pepper

11 Incidence of collar infection (%) in integrated management of Phytophthora foot rot of black pepper

12 Incidence of wilted vines (%) in integrated management of Phytophthora foot rot of black pepper

LIST OF FIGURES

Figure No.

Title

1 In vitro evaluation of native microbial antagonists against Phytophthora capsici

2 In vitro evaluation of plant extracts against Phytophthora capsici

3 Bioassay of fungicides against Phytophthora capsici causing foot rot of black pepper

4 Incidence of leaf infection (%) in integrated management of Phytophthora foot rot of black pepper

5 Incidence of yellowing index (%) in integrated management of Phytophthora foot rot of black pepper

6 Incidence of defoliation index (%) in integrated management of Phytophthora foot rot of black pepper

7 Incidence of collar infection (%) in integrated management of Phytophthora foot rot of black pepper

8 Incidence of wilted vines (%) in integrated management of Phytophthora foot rot of black pepper

LIST OF PLATES

Plate No.

Title

1 Symptoms of Phytophthora foot rot of black pepper on different parts

2 Culture plates of Phytophthora capsici

3 Pathogenicity test of Phytophthora capsici

4 In vitro evaluation of native microbial antagonists against Phytophthora capsici

5 In vitro evaluation of plant extracts against Phytophthora capsici

6 Bioassay of fungicides against Phytophthora capsici

7 Screening of black pepper varieties against Phytophthora capsici

8 Integrated management of Phytophthora foot rot of black pepper

1. INTRODUCTION

Black pepper (Piper nigrum L.) the king of spices is a traditional, historic spice crop which has been under cultivation since ancient times in India. It belongs to family Piperaceae. Black pepper is a woody climber and is a native of the Western Ghats of South India. The cultivation of black pepper is mainly confined to India, Brazil, Indonesia, Malaysia, Thailand, Sri Lanka and Vietnam. In India black pepper is being cultivated in Kerala (96%), Karnataka (3%) and to a lesser extent, in Maharashtra, Andhra Pradesh, Tamil Nadu and north eastern regions (Anonymous, 2005).

In India, black pepper is being cultivated in an area of 2.2 lakh ha with a production of 70,000 tonnes. During 2005-06 India exported 28,750 tonnes of black pepper amounting to Rs. 306.2 crores (Anonymous, 2005).

In Karnataka, black pepper is cultivated in an area of 10,690 ha with a production of 2360 tonnes during 2005-06 (Anonymous, 2005). It is mainly cultivated in Kodagu, Uttara Kannada, Dakshina Kannada, Shimoga and Chikmagalore districts as mixed crop in plantation such as arecanut, cardamom, coffee and rubber whereas in Kerala it is being grown as pure crop trained on Erythrina indica Lam. K.

Indian black pepper is preferred in the international market due to its proper combination of pleasant flavour, taste, piperine content and essential oil. Black pepper is not only used as a condiment but also, widely used in culinary preparations, food processing, perfumery and as an important ingredient in most of the Ayurvedic medicine preparations.

During 1930 to 1940 India was leading by contributing 80 per cent of world production of black pepper. But presently Malaysia, Vietnam and Brazil are leading in the production of black pepper where it is being intensively cultivated as pure crop. The drastic drop in the black pepper production in India has been attributed mainly for pronounced mortality of vines by the dreaded disease foot rot caused by Phytophthora capsici emend, Alizedeh and Tsao. The other major constraints for low production of black pepper are old gardens occupied with traditional cultivars having poor genetic potential, non-adoption of improved package of practices and bad management of gardens.

In Uttara Kannada which is situated in upper region of Western Ghats, black pepper is mainly cultivated in moist valleys in arecanut plantations wherein arecanut trees serve as live standards for training black pepper. Due to epiphytotic appearance of Phytophthora foot rot disease of black pepper most of the gardens have been wiped out since 1978 (Sastry, 1982 and Dutta, 1984).

A well distributed high rainfall (2,500 mm) with less sunshine (1 to 3 h) during monsoon are highly congenial for the development of the disease. The pathogen is versatile in nature to infect all parts of the plant i.e. root, collar, stem, leaves, inflorescence and berries. The black pepper vine succumbs to infection at any of its growth stage. Since the pathogen is soil borne, the spread of the pathogen is mainly through soil and water (Nambiar and Sarma, 1977). Soil borne inoculum plays an important role in the onset of epiphytotics of Phytophthora diseases (Thorold, 1955; Holliday and Mowat, 1963; Okaisabor, 1971 and Onesirosan, 1971).

Since the pathogen is soil borne, native antagonistic microorganisms play a major role in keeping the population of pathogen at low levels. Though work on screening of some of the commercially available biocontrol agents for their antagonistic effect on P. capsici is available, not many reports on isolation, identification and studies on antagonistic ability of native microorganisms (isolates).

Locally available leaf materials in black pepper growing areas may have inhibitory effect on the pathogen, and it may be due to presence of toxic substances. Application of leaf material like neem, pongemia and glyricidia have been recorded to promote population of native antagonistic microflora which in turn suppress the pathogen.

Earlier workers recommended one per cent Bordeaux mixture to manage the disease as preventive fungicide. But after the onset of the disease the fungicide does not give satisfactory control of root and collar infection. Hence, there is a need to search for new

fungicides which can bring down the pathogen population in soil and can control leaf, stem, spike, root and collar infections.

In recent years, the increase in the use of potential hazardous fungicides (in agriculture) has been subject of growing concern of both environmentalists and public health authorities. Now a days, integration of several methods have been subject of extensive research for the disease management. Integration of chemicals and biological agents for managing soil borne disease has been considered as a novel approach, as it requires low amounts of chemicals, thereby reducing cost of control as well as pollution hazards, with minimal interference of biological equilibrium (Papavizas, 1973). Therefore, an attempt has been made to integrate chemicals, biological agents and organic amendments to manage the disease.

With this background, the present investigation was taken up with the following objectives.

1. Survey for the disease incidence, isolation of P. capsici and proving its pathogenicity

2. Isolation and evaluation of native antagonistic microorganisms

3. In vitro evaluation of botanicals and fungicides on P. capsici

4. Screening of black pepper varieties against P. capsici

5. Integrated management of Phytophthora foot rot of black pepper

2. REVIEW OF LITERATURE

Black pepper (Piper nigrum L.) originates from West tropical forests of Western Ghats of Kerala, India. It is primarily a small holder’s crop and foot rot disease is the major limiting factor in its production (De Waard, 1986). The foot rot or quick wilt or quick decline of black pepper is caused by Phytophthora capsici. This is a soil borne fungus which attacks the roots, stems, leaves, branches and fruit spikes of black pepper vine. The fungus is spread by water and soil cultivation operations in pepper gardens. The roots and collar portion of stem are adversely affected leading to rapid wilting and death of the entire vine. The disease spreads out from vine to vine in a non random, centrifugal fashion (Anandaraj and Sarma, 1990).

Several attempts have been made to manage the Phytophthora disease by chemicals, botanicals, resistance and biological means. An attempt has been made to review the work on these aspects particularly on P. capsici. However, the literature on other related species of Phytophthora of relevance to some aspects under present investigation has also been mentioned.

2.1 HISTORY AND DISTRIBUTION

In Lampung (Indonesia) during 1885, sudden wilting and death of the black pepper vines was reported. Severe incidence of black pepper vine death was reported in Wynad region of Kerala as early as 1902 (Menon, 1949) and was investigated by Barber (1902, 1903 and 1905) and later by Butler (1906 and 1918) but the etiology was not realized. During 1936, the causal agent was identified as Phytophthora sp. and named it as Phytophthora palmivora var. piperina Dastur. Though Phytophthora isolation from black pepper was reported by Venkata Rao (1929) from Karnataka, the first authenticatic record of wilt of black pepper due to Phytophthora in India was reported by Samraj and Jose in 1966 from Kerala, adopting the identification of Muller (1936) as P. palmivora var. piperina.

In Sarawak (Malaysia) the disease was reported in 1941 (Newman, 1941; Thompson, 1941). Miller (1953) reported the severe out break of the disease in Sarawak.

The severity of the disease has been reported from several black pepper cultivating countries viz., Indonesia (Muller, 1936), Puerto Rico (Gregory et al., 1960), Sarawak (Holliday and Mowat, 1963), Brazil (Holliday, 1965), Jamaica (Leather, 1967), Thailand (Tsao and Tummakate, 1977) and Malagasay republic (De Waard, 1979).

Sarkar et al. (1985) reported the disease severity in different states, viz. Kerala, Karnataka, Tamil Nadu and Assam. The disease has also been observed in severe form in Uttara Kannada and Shimoga districts of Karnataka state in India (Sastry and Hegde, 1982; Dutta, 1984; Subramanyam, 1993; Jahagirdar, 1998).

2.2 ECONOMIC IMPORTANCE

The information on exact crop loss due to disease was lacking. However, in India, Samraj and Jose (1966) recorded death of pepper vines about 20 to 30 per cent in Cannanore and Calicut district (Kerala). Nambiar and Sarma (1977) recorded 25 to 30 per cent loss in some gardens in Cannanore and Calicut districts (Kerala). In Sarawak (1953-56), the loss was about 7000 tonnes amounting to 17 billion pounds (Holliday and Mowat, 1963). Leafman (1934) recorded death of vines of about 10 per cent in West Borneo.

The crop loss survey for three years i.e., 1982 to 1984 in Calicut and Cannanore districts of Kerala revealed that the disease incidence was 3.7 and 9.4 per cent causing vine death of about 1, 88, 947 and 10, 16, 425 amounting to an annual loss of 119 and 905 metric tonnes of black pepper in the above districts, respectively (Anandaraj et al., 1988).

An epiphytotic appearance of the disease during 1967 to 1968 in Lampung area resulted in mortality of vines up to 40 to 50 per cent. The loss due to the disease in black pepper cultivating countries of the world estimated at 3 to 5 per cent of the total planted area amounted to US$ 4.5 to 7.5 million per annum (De Waard, 1979).

In Karnataka, Sastry (1982) and Dutta (1984) have reported heavy loss of black pepper crop due to Phytophthora foot rot. Subramanyam (1993) recorded 60 to 80 per cent disease incidence in Uttara Kannada district. Jahagirdar (1998) recorded an average incidence of foot rot of black pepper was 48.24 per cent during 1997 when compared to 44.64

per cent during 1996. Disease incidence was in the range of 10.5 to 68.5 and 19.2 to 69 per cent in 1996 and 1997, respectively.

2.3 SYMPTOMATOLOGY

The Phytophthora foot rot disease occurs mainly during the South-West monsoon period, (June to September) where weather conditions are favorable (Anandaraj et al., 1988). High soil moisture, high relative humidity, shorter duration of sunshine hours, high and well distributed rainfall and low temperature are very conducive for the disease development (Sarma et al., 1988).

The detailed symptomatology of the disease was described by Sarma and Nambiar (1980). The P. capsici, a soil borne fungus, infects all parts of the black pepper vine, i.e., leaves, stem, inflorescence, collar and roots that led to leaf rot, stem rot, dropping of inflorescence, collar rot and root rot respectively. Among these infections, collar rot and root rot cause severe and sudden mortality of the vines.

Leaf infection of black pepper vines appears as grey centers, surrounded by alternating dark and light brown zones with peripheral water soaked margins (Muller, 1936). This dual zonation occurred in alternate wet and dry weather but not in continuous wet condition. Holliday and Mowat (1963) reported uniform brown lesions with fimbriate margins on the leaves. Wilting and rapid defoliation generally were the first symptom of the disease (Alconero et al., 1972), the tender leaves were highly susceptible than mature ones and the lower surface of leaf was more susceptible than upper surface (Turner, 1969).

The infection first appears on tender shoot tips or leaves of runner shoots arising from the base of the black pepper vines spreading on the ground. (Sarma et al., 1988). Later the infection spreads and reaches to leaves at lower region of the bush. Gradually, the infection spreads to the upper regions of the vine including spike. Foliar infection is more serious in areca-pepper mixed cropping system because of the conducive macroclimate.

Spike infection at the distal end results in severe spike shedding by abscission. Black lesions are developed at distal end of the spike and infecting occasionally a few berries only (Holliday and Mowat 1963; Nambiar and Sarma 1977).

Holliday and Mowat (1963) reported that fruit bearing plants were some what more susceptible than younger plants. They also found that pathogen penetration of the stem from roots and shoot collapse occurred with the greatest frequency in plants treated with large amounts of inoculum.

Stem infection as dark brown lesions on the lateral branches result in wilting and shedding. The tender berries on the spikes borne on such infected branches become shriveled and the spikes are shed. Breaking of the nodal region of the stem is characteristic symptom.

The collar and root infection are fatal and the infected vines die with in 10-20 days. Hence, the disease is locally called “quick wilt’. The collar rot infection occurs either at the collar or just above or below the soil level. Collar and root infection go unnoticed until foliar yellowing is recognized. The infection at initial stage starts as water soaked which is same as leaf infection. The lesions later turn brown to dark brown within two to three days and appear as slimy dark patch. Young leaves become flaccid followed by yellowing and defoliation. The affected portion is wet discolored slimy emitting foul smell. Vascular discolorations observed in many cases but not consistently (Nambiar and Sarma, 1977). During the advanced stage of infection the cortex get disintegrated and peeled off. The infection of the collar gradually progress downwards and spreads to the root system. This results in rotting of the root (Holliday and Mowat, 1963).

Root infection of the vines go unnoticed without any visible aerial symptoms. The root infection starts on finer feeder roots (Holliday and Mowat 1963), later spreads to the main roots and the collar. The black pepper vines remain healthy until large portions of the roots are damaged. In the advanced stages of the root rot, foliar yellowing of the vine, and shedding of leaves, spikes and lateral branches are noticed. The amount of defoliation due to root rot infection is equal to root damage. The root loss to regeneration determines the spread of the decline and death of the vine. During the post monsoon season with depletion of soil

moisture, the remaining root system is unable to support the vine, so the entire vine collapse with wilting and drying of leaves.

Foliar yellowing, flaccidity, defoliation, breaking of the stems at nodal regions and spike shedding are the characteristic aerial symptoms of root rot and collar rot infections (Muller, 1936 and Holliday and Mowat 1963). Detailed symptomatology of the disease has been described by Sastry (1982), Anandaraj et al. (1988) and Sarma et al. (1988).

2.4 ISOLATION AND PROVING PATHOGENICITY

In black pepper, isolation of the organism from the infected tissues of root and collar has been difficult, compared to isolation from diseased leaves (Sarma et al., 1982). However, leaching the tissues in running tap water for 24 hours and plating on media has increased the frequency of positive isolations.

Holliday and Mowat (1963) reported successful isolation of Phytophthora from fresh foot rot affected stems and roots of black pepper using plain agar. Baiting techniques with leaf disks (Muller, 1936) or castor seeds (Narasimhan and Ramakrishnan.1969; Sastry, 1982; Sastry and Hegde, 1982 and Subramaniam, 1993), apple (Holliday and Mowat, 1963) has been well documented as the most successful method in isolation of Phytophthora from infected black pepper soils.

The number of selective agar media containing antibacterial antibiotics and selective fungal agents have been proved successful in Phytophthora isolations from soil and plant tissues (Eckert and Tsao, 1960; Kuhlman and Hendrix, 1965; Flowers and Hendrix, 1969; Tsao and Ocana, 1969; Sneh, 1972; Fugisawa and Masago, 1975; Masago et al., 1977; and Tsao and Guy, 1977 and Kueh and Khew, 1982). Leaflets of Albizia falcatarea were used as baits to isolate Phytophthora palmivora (Butl). Butt. MF4 from soil (Anandaraj and Sarma, 1990).

Zoospore suspensions have been successfully used by several workers to establish the pathogenicity of Phytophthora spp. on their hosts (Turner, 1967; Mehrotra, 1972 and Mc. Donald and Duniway, 1978). Sastry (1982), Dutta (1984) and Subramanian (1993) also used zoospore suspensions to establish the pathogenicity of Phytophthora spp. on their hosts.

2.5 BIOLOGICAL CONTROL

The impact of Phytophthora spp. on many economically important crops worldwide has been well documented (Gregory, 1983). Recent literature reviews indicate that diseases caused by Phytophthora species have become an important concern in production of many agricultural, horticultural and forest plant species. Biological control is the use of organism, gene or gene products to regulate a pathogen and can be used with strategies intended to keep (i) inoculum density below the economic threshold level; (ii) retard or exclude infection; and (iii) maximize the plant system for self-defense (Cook, 1977).

Trichoderma spp. are becoming well known for their capacities to control soil borne pathogens. Biological control that may already be an important component (Pegg and Whiley, 1987) of some practices (e.g., mulching, organic amendments), remains the ‘cinderella’ of integrated control. This is mainly due to insufficient efforts made to identify the microbial components present in suppressive soils. Further, the private enterprises have shown little interest in investment and development of such practices. Despite of these various obstacles some progress is being made in identifying potentially active anti- Phytophthora microbial agents. Very recently, Trichoderma and Gliocladium species pot tests were identified for their ability to inhibit Phytophthora species. Understanding the ecological factors affecting the distribution of Trichoderma and Gliocladium in their natural habitats may lead to an understanding of population dynamics of the two antagonists in soils and other habitats and of their survival and proliferation in soil and rhizosphere. Some successful biological control of soil borne pathogens like Sclerotium rolfsii, a causal agent of root rot of several agricultural crops has been achieved (Chet et al., 1979 and Elad et al., 1980), but only when applied at relatively high inoculum rates.

Books and review articles have been published on microbial antagonism of Trichoderma spp. (Wood and Tveit, 1955; Boosalis, 1964; Baker, 1968; Baker and Cook, 1974 and Cook 1977).

Several fungi, bacteria and actinomycetes are found to be antagonists to various species of Phytophthora. Kaster (1938) found that Trichoderma koningii, Trichoderma lignorum (Tode) Harz were antagonistic to Phytophthora citrophthora. Trichoderma lignorum was found to be antagonistic to Phytophthora parasitica (Weindling, 1932) and several strains of Phytophthora arecae (Coleman) Pethybridge (Thomas, 1939). Niethammer (1937) found that Trichoderma koningii extended a chemotherapeautic action on Phytophthora spp. Nambiar and Sarma (1977) isolated Trichoderma spp. from roots of black pepper vines and noted the lysis of mycelium of Phytophthora capsici due to over growth of antagonist. The reviews on Trichoderma spp. as biological agent against betel vine wilt was reviewed by Tiwari and Mehrotra (1968), root rot of avacado (Zentmeyer, 1963, 1967) and of many other Phytophthora diseases has been reviewed by (Baker and Cook 1974). Trichoderma viride was found to protect the host plants against Pythium ultimum Trow (Liu and Vaughan, 1965). Phytophthora splendeus Brawn (Bolton, 1978) and Phytophthora aphanidermatum (Odson) Fitzp. (Bolton, 1980).

Roiger and Jeffers (1991) reported evaluation of Trichoderma spp. for biological control of Phytophthora crown and root rot of apple. Isolates of Trichoderma spp. were evaluated with two delivery system. A viscous suspension of conidia in an aqueous gel was applied to seedling roots or colonized mixture of peat and wheat bran (peat) was added to soil. Isolate Two 55 of Trichoderma virens in peat bran preparation was found superior to rest of treatments and application of biocontrol agent was better delivery method.

Two isolates of Pseudomonas corrugata (PC 13 and PC 35) and three of Pseudomonas fluorescens (Pf15, Pf16 and Pf 27) were used in the biological control of Pythium root rot of cucumber Pf15 isolate significantly reduced the disease incidence and produced 85% more marketable fruits than rest of the treatments (Rankin and Paulitz, 1994).

Use of biocontrol agents like Glomus fasciculatum, T. hamatum and G. virens were found effective against Phytophthora foot rot of pepper (Anandaraj et al., 1995). Isolation and identification of micro-organisms antagonistic/hyper-parasitic to Phytophthora capsici in black pepper plantation of Kerala and Karnataka showed predominance of Trichoderma viride, T. harzianum, T. koningii and Gliocladium virens (Anon., 1996). Biocontrol studies against foot rot disease revealed that T. viride was found to be effective in controlling wilt disease with incidence (10%). In biocontrol studies of Phytophthora foot rot disease, use of antagonistic organism T. viride @ 150 ml/vine along with 5 kg of FYM was found effective in trials at Sirsi and Panniyur (Anon., 1997).

Effectiveness of T. harzianum and other species in controlling soil borne pathogens has been reviewed (Chet et al., 1987). Both T. viride and T. harzianum overgrew and suppressed the growth of P. capsici (Subramanyam, 1993). He also used Trichoderma spp. in field successfully.

In vitro screening of bioagents such as Trichoderma viride, T. harzianum, T. hamatum, T. viride (Mudigere isolate), Gliocladium virens and Pseudomonas fluorescens against Phytophthora capsici revealed that the T. viride (Mudigere isolate) recorded highest per cent inhibition of colony followed by Gliocladium virens and P. fluorescens (Jahagirdar, 1998).

Three bacterial isolates, B5, B7 and B13 were effective in controlling the disease and reducing mortality to 43 per cent and 57 per cent, respectively. Also, they provided prolonged protection and reduced mortality for upto 90 days after inoculation (Jubina and Girija, 1998).

Sodsa-art and Soytong (1999) reported that application of mixtures of Trichoderma and Chaetomium mycofungicides could significantly reduce disease incidence (which averaged 8.6 per cent), followed by the application of Trichoderma and Chaetomium where disease incidence was 10.9 per cent and 22.6 per cent, respectively.

Anith and Manomohandas (2001) reported that Trichoderma harzianum and Alcaligenes sp. strain AMB applied alone or in combination significantly reduced the incidence of Phytophthora capsici induced nursery rot disease of black pepper.

Among the 64 different bacterial isolates tested, PN-026 showed maximum suppression of lesion development during screening by shoot lesion assay and reduced the disease incidence significantly compared to other bacterial antagonists (Anith et al., 2002).

The highest control of foot rot and wilt was with Trichoderma viride mixed with FYM + Bordeaux mixture and T. viride with FYM treatment respectively (Kannan and Revathy, 2002).

Rajan et al. (2002) isolated a number of Trichoderma isolates and were screened both in vitro and in vivo. Isolates T. virens-12 and T. harzianum-26 were found more effective to control the foot rot disease and isolate T. harizianum-26 most adaptive to the rhizosphere of black pepper.

Bacterial antagonists of Phytophthora capsici were isolated and screened by dual culture technique and further by shoot assay for suppression of lesion caused by the pathogen. Isolate PN-026, showing the highest suppression of lesion development in the shoot assay was most efficient antagonist in reducing P. capsici induced nursery wilt of black pepper (Anith et al., 2003).

Among isolates of Trichoderma spp., the per cent inhibition of Phytophthora capsici varied from 0 to 84 per cent and isolates of bacteria were inhibited P. capsici upto 50 per cent under in vitro evaluation (Anandaraj and Sarma, 2003).

Screening of 222 isolates of Trichoderma spp. in vitro for their antagonism to Phytophthora capsici indicated that the inhibition of P. capsici by the isolates varied from 20 to 84 per cent. Eight isolates were found disease suppressive, the disease incidence varying from 0 to 30 per cent.

2.5.1 Isolation and enumeration of Trichoderma spp.

Abdal-El-Moity et al. (1982) developed selective medium containing fungicide allyl alcohol and the fungicide Viclozolin for isolation of Trichoderma spp.

Rose Bengal and Pentachloronitrobenzine (PCNB) were used together with captan as the basic antimicrobial agents for developing a semi-selective medium for the quantitative isolation of Trichoderma from soil (Elad and Chet, 1983). A new semi-selective medium with either rosebengal or PCNB has also been described for isolation of Trichoderma spp. (Papavizas, 1982). Another Trichoderma medium (TME) with or without benomyl, gave good results with soil that did not contain Mucor and Rhizopus (Abd-El-Moity et al., 1982; Papavizas, 1982). It was further improved with addition of alkylalyal polyethylene alcohol (Papavizas and Lumsden, 1982) and used effectively in enumeration of rhizosphere microflora.

2.6 EFFECT OF PLANT EXTRACTS

Many plants are known to contain substances which can be used to control plant pathogens. Smale et al. (1964) have surveyed green plants for antimicrobial properties against bacteria and fungi. Many investigators have tried to identify the toxic metabolites from wild hosts or weeds or cultivated plants (Abbas and Ghaffar, 1973; Afiffi, 1975; Afiffi and Dowidar, 1976; Ahmed and Agnihotri, 1978).

Chamount (1979) tested aqueous extracts of eight flowering plants on 51 fungi and found that Phytophthora and Pythium were among the most resistant ones. Chamount and Jolivet (1978) tested several plant extracts against P. cinnamomi and some other fungi among which inhibitory effects were exercised by Vincetoxicum officinale Moench., Saponaria ocymoides L., Aster alpinus L., Chrysanthemum alpinum L., Paris quardifolia L., Polygonatum verticilliatum L., Digitalis grandiflora Lamarck and Veronica fructiculosa L., P. cinnamomi was one of the fungi which was the most resistant to the action of these extracts. Gerrettson et al. (1976) found that growth and pathogenicity of P. cinnamomi were inhibited by Pinus radiata D.Don. bark in water and nursery soil. Whitefiled et al. (1981) found that the steam volatile extracts of the roots of Acalia pulchella R. Br. restricted mycelial growth, suppressed sporangial production and germination and reduced zoospore germination of P. cinnamomi in culture.

Sivasithamparam (1981) evaluated the effect of extracts from three barks and saw dust against P. cinnamomi and found that all the isolates tested produced more sporangia in cold water extracts from composted Pinus barks than in other media, but sporangial production was strongly inhibited by extracts from Eucalyptus catophylla Robert Brown and E. wandoe Blakey and by all the saw dust extracts

Phytophthora infestans (Mont.) de Bary, was controlled up to 80 per cent or more by 20 plant extracts the most effective being from Orixa japonica Thumb (Rutac) and Lycoris radiata Herb. The extract from O. japonica was subjected to four tests and gave results similar to those achieved with the usual copper sulphate preparations. L. radiata extract was also very promising as a substitute for copper sulphate against P. infestans (Anon., 1959), Kovacs (1964) reported that zoospores of P. infestans were prevented from leaving the sporangium by 1: 1000 onion juice and 1:1000 horse radish juice rendered them immobile, while potato leaf juice had the reverse effect.

Vasyukova et al. (1977) found that both deltozid and deltonin (Steroid saponins from the rhizome of deltoid yarm) were inhibitory to zoospores of P. infestans. Hegde (1983) tested the inhibitory effect of green leaf extracts of six plant species against P. palmivora and found that Xylia xylocarp (Rosb.) Taub. was the most effective one, followed by Terminalia paniculata and Glyricidia maculata N. B. and K. The least effective one was that of Azadirachta indica A. Juss.

Extracts of Azadirachta indica, Basella alba, Ocimum sanctum and Phyllanthus traternus were tested against Phytophthora capsici. All the plant extracts inhibited the P. capsici, with A. indica the most effective (Louis et al., 1996).

Anandaraj and Leela (1996) tested different aqueous leaf extracts against vegetative and reproductive phases of P. capsici. Among those, mycelial growth, sporangial production and release and zoospore germination were completely inhibited by Chromolaena odorata extracts at 2 per cent concentration. Similar results occurred with Azadirachta indica although mycelial growth was inhibited by 75.5 per cent.

Among various plant extracts, essential oil from leaves of allspice showed promising fungitoxicity, followed by Chromolaena odorata and Zanthoxylum rhetsa seed oil. Allspice leaf oil completely inhibited mycelial growth of P. capsici at 0.5 per cent whereas C. odorata leaf extract and Z. rhetsa seed oil inhibited mycelial growth at 2 per cent concentration (Leela et al., 2003).

2.7 CHEMICAL CONTROL

Despite of the many achievements in modern agriculture, chemical control still holds a strong performance in combating certain destructive plant diseases. Disease management strategies logically integrate different technologies and are based on accurate understanding of destructive potential of disease (De Waard et al., 1986). Spraying and drenching with Bordeaux mixture has been recommended for control of pepper wilt due to Phytophthora capsici by several workers (Dastur, 1927, 1935; Uppal, 1931; Asthana, 1947; Subramanian and Venkata Rao, 1970; Narasimhan et al., 1976).

Among the different chemical formulations tested, spraying and drenching with 1 per cent Bordeaux mixture before and after onset the of monsoon and pasting with 10 per cent Bordeaux paste to treat the stem collar were found effective for wilt of black pepper (Nambiar and Sarma, 1977). In the in vitro screening against Phytophthora capsici and Phytophthora meadii Mc Rae, Bordeaux mixture (1%), Blitox, Bayer 7072 and Metalaxyl were found effective in inhibiting growth and sporangial formation (Sastry, 1982). Studies on metalaxyl as effective fungicide agent Phytophthora parasitica var. nicotianae causing black shank of tobacco was reported by Vasilakakis et al. (1979) and Phytophthora infestans on tomato plants (Cohen et al., 1979).

The majority of soil borne species against which metalaxyl is used, including Phytophthora megasperma f. sp. glycinea, Phytophthora cinnamomi, Phytophthora nicotianae and Phytophthora palmivora are very sensitive (Coffey and Bower, 1984a). Fosetyl aluminium and particularly its break down product, phosphonic acid (Cohen and Coffey, 1986; Quimettee and Coffey, 1988, 1989) are also quire active against some Phytophthora species

Laboratory evaluation of Ridomil against Phytophthora parasitica var nicotianae revealed significant reduction in growth and sporulation of fungus at 0.1, 0.2, 0.3 and 0.4% concentration (Reddy and Nagarajan. 1980). The systemic fungicide metalaxyl (Ridomil, matco 8-64), Fosetyl Al (Aliette) both as foliar spray and soil drench were found effective against Phytophthora capsici in field conditions (Ramachandran and Sarma, 1985a). Similar

reports on efficacy of metalaxyl against Phytophthora infections in black pepper has been reported by Sastry (1982) and Anonymous (1986).

Ramachandran et al. (1988) opined that in the field evaluation of five systemic fungicides, metalaxyl was highly effective in suppressing soil population of Phytophthora palmivora. The several reports on other effective fungicides tested both in vitro and in vivo against Phytophthora capsici are metalaxyl, metalaxyl-ziram, Fosetyl-Al and Carbamate (Ramachandran and Sarma, 1989; Ramachandra et al., 1990b). Root feeding with metalaxyl + mancozeb (0.2%) has given better control of Phytophthora foot rot of black pepper in Dominican Republic (Matsuda et al., 1996). Use of potassium phosphonate (Akomin) at 0.4% as foliar spray and soil drench has significantly brought down the Phytophthora infection of black pepper (Sarma et al., 1995).

Ramachandran and Sarma (1990) evaluated systemic fungicides viz., Metalaxyl, Fosetyl Al, Ethajole, Oxadixyl and Propamocarb for their bio-efficacy on different phases of Phytophthora capsici. Metalaxyl, Ziram and Fosetyl Al were superior to Bordeaux mixture in reducing the disease.

Nair and Sasikumaran (1991) reported that, among 5 fungicides tested to control the infection of Piper nigrum by P. capsici, Bordeaux mixture gave the best control followed by metalaxyl, copper oxychloride and captafol.

Metalaxyl MZ at 250 ppm was recorded to inhibit cent per cent radial growth of P. capsici (Subramanyam, 1993). He also reported that spraying and drenching with metalaxyl MZ (@1.25 g/litre) has reduced the population of P. capsici in the soil and per cent survival of vines was increased.

Studies with newer fungicides revealed that the treatment consisting of all cultural practices + 1 kg neem cake + 3 g phorate/vine + first spray with 1% Bordeaux mixture + 0.2% Akomin (second) recorded minimum defoliation (6.74%) and foliar yellowing (5.65%) without any death of vines (Anon. 1997). Spraying with 1% Bordeaux mixture + drenching with 0.2% copper oxychloride was found effective against Phytophthora foot rot (PFR) of black pepper (Anon., 1996). Studies at Panniyur including standardization of management practices with spraying of 0.2% Akomin followed by spraying and drenching with 1% Bordeaux mixture were found to be effective in checking foot rot disease under different shaded conditions(Anon., 1997).

In vitro screening of four fungicides viz., metalaxyl MZ 72 WP, Aliette, Akomin and Mancozeb at four concentrations viz., 500ppm, 1000 ppm, 1500 ppm and 2000 ppm, metalaxyl MZ 72 WP (2000 ppm) recorded average minimum colony diameter followed by Aliette (2000 ppm), Metalaxyl 72 WP (1500 ppm) and Akomin (2000 ppm) (Jahagirdar, 1998).

Veena and Sarma (2000) studied the uptake and persistence of potassium phosphonate recommended for the control of foot rot of black pepper. Potassium phosphonate at 500, 1000 and 2000 ppm concentrations, both as aerial spray and soil drench, indicated that maximum reduction of foliar in infection (upto 86.4%) was noticed 4 days after treatment whereas root rot suppression (upto 70%) 8 days after treatment. They also reported prolonged protection beyond 30 days could be obtained with 2400 ppm to 4000 ppm concentration. There was no phytotoxicity on black pepper even at 4000 ppm.

2.8 HOST PLANT RESISTANCE

There is no evidence of absolute resistance to Phytophthora was available in cultivars. But, some what of resistance of certain cultivars like Kulluvalli, Palaulaut, Belantung and Bangka had been identified (Sitepu and Prayitno, 1979).

For majority of Phytophthora problems effective control practices have been much slower to evolve. Selection and breeding for resistance or tolerance have been advocated. In most instances, however, suitable germplasm has been difficult to find, particularly in tree crops where 15-20 years of time frame is needed to evaluate resistance. A research for root stock resistance or tolerance has been actively perused, especially in India since black pepper originates from Kerala. Some wild relatives including Piper colubrinum, P. hispidum and P. arifolium are resistant.

Techniques for mass screening of open pollinated seedling progenies and to assess relative degree of tolerance resistance in rooted cuttings to Phytophthora capsici have been developed (Sarma and Nambiar, 1979; Sarma et al., 1990). Though it is quite hard task to identify high degree of resistance in open pollinated crops extent of field tolerance is greatly appreciated.

Muller (1936) was the first to report black pepper variety Belantung from Indonesia as resistance to foot rot. Indian pepper cultivars, Uthirankotta and Indodnasian varieties Djambi and Belantung possess appreciable resistance (Holliday and Mowat. 1963). Ruppel and Almeyda (1965) opined that out of five pepper species tested, Piper adunum. Piper seabrum sw. and Piper treleasanum Bitt. and Wils showed partial resistance.

Albuquerque (1968a) observed resistance in Phytophthora colubrinum Link., Phytophthora obliqum Ruiz and Pav. var. eximum and Balakotta were found as resistant (Turner, 1971, 1973). Kuch and Khew (1980) reported root inoculation and leaf inoculation with zoospores as effective screening techniques useful in selecting for resistance in black pepper to Phytophthora palmivora. Sarma et al. (1982) reported that out of 41 cultivars and 73 wild types of Piper spp. Tested cultivars, Narayankodi, Kalluvally, Uthirankotta and Balankottta were found tolerant. Hegde (1983) conducted mass screening of seven cultivars in wilt sick plot and could not get a single resistant plant. Dutta (1984) tested the seedling raised from seeds and cuttings of healthy pepper vines survived in badly infected garden and reported that none of them were resistant.

Black pepper varieties viz., Kutching cultivar, Bangka, Belantung, Jambi, Karimunda, Lampung, Daun kecil, Lampung daun lebar, Panniyur-1 and Uthirankotta were highly susceptible to P. capsici. While varieties viz., Cheriakanyakadan and Balankotta were less susceptible (Kueh Tiong Kheng and Simsoon Liang, 1988).

During 1987, 140 cultivars, 174 hybrids, 72 wild types of black pepper and a large number of seedlings raised from open pollinated seeds were screened for reaction to Phytophthora capsici. Among them tolerant reaction was found in 15 cultivars, 12 hybrids and 50 open pollinated seedlings (Ramachandran et al., 1988).

During 1979, about 1200 open pollinated high yielding varieties Kuching black pepper seedlings in Sarawak were inoculated with P. palmivora (Butler) Butler. By the end of 1980, nine seedlings appeared to be resistant to fungus (Mohd and Hussin, 1986).

Piper colubrinum was immune to P. capsici and its adaptability as root stock to black pepper was poor. Cultivar Karimunda was highly susceptible to P. capsici.

Sarma et al. (2000) screened 137 hybrids for their reaction to Phytophthora capsici through stem inoculation techniques, three hybrids HP-423, HP-664 and HP-756 showed tolerant reaction.

Among 70 hybrids, 25 cultivars and 16 Kottandan selections screened for resistance against P. capsici 7 hybrids 3 cultivars and 9 accessions were found tolerant (Veena et al., 2003).

Screening of 343 black pepper hybrids, 7 cultivars and 9 wild accessions for their reaction to Phytophthora capsici indicated that 9 hybrids, 4 cultivars and 2 wild accessions were tolerant. Seedling progenies of P-24 (resistant line) and KS-27 (susceptible line) were screened against P. capsici and a higher percentage of seedlings of P-24 showed a tolerant reaction (Anon., 2003).

2.9 INTEGRATED MANAGEMENT

Integrated management is the harmonious blending of various methods in proper sequence and timing so as to create least harmful effects on man and environment. The various components of integrated management are eco-friendly, economically feasible and compatible.

Conceptually, Integrated Disease Management (IDM) or Integrated Pest Management (IPM) involves the selection, integration and implementations of control based on predicted economic, ecological and sociological constraints. This technology therefore, seeks maximum use of naturally occurring controls including weather, disease agents, native as well as introduced antagonists.

In these cases, the ultimate disease control is brought about by direct inhibition of the pathogen as well as by increased microbial antagonism. Therefore, it is generally indicated as integrated control (Baker and Cook, 1974). Curl et al. (1976) observed that combined application of PCNB with Trichoderma harzianum alone in cotton seedling disease in green

house studies. Henis et al. (1978) opined that integration of PCNB (µg/g of soil) with Trichoderma harzianum effectively brought down the population of Rhizoctonia solani causing damping off in radish. Lewis and Papavizas (1981) obtained field control of root rot of cucumber and crown rot of pepper by integration of chlorothalonil and metalaxyl respecting with Trichoderma harzianum and cultural practices.

Chandra (1984) observed that integration of both chemical and biological measures has synergistic effect on control of damping off in sugar beet Mukhopadhyay et al. (1986) and Mukhopadhyay and Chaturvedi (1986) also obtained successful control of damping off of tobacco and brinjal by integrating Trichoderma and metalaxyl. Subramanian (1993) observed integrated application of metalaxyl-neem cake + Trichoderma found effective on Phytophthora capsici causing wilt of black pepper. The application of neem cake (1 kg/ha) + phorate (30 g/vine) + Bordeaux mixture + Akomin (0.4%) found very effective in Phytophthora disease of black pepper (Anon., 1997). The combined application of Trichoderma harzianum + Akomin significantly brought down the populations of Phytophthora causing foot rot of black pepper (Anon., 1997).

Application of neem cake + Trichoderma harzianum + Ridomil MZ (Metalaxyl) + garlic and mustard seed extract + mulching of the wet soil with transparent polythene sheets during the hot summer was most effective in reducing soil population of P. capsici to 25.76 per cent from 89.76 per cent (control) with considerable increase of T. harzianum, other fungi bacteria and actinomycetes which were antagonistic to P. capsici and resulted in maximal survival of vines (Hegde and Anahosur, 1998).

Jahagirdar et al., (2000) recorded lower disease incidence with the treatments Trichoderma viride + Metalaxyl + Akomin; Metalaxyl + Akomin; Metalaxyl alone; T. viride + MPG-3. The per cent increase in yield was above 50 per cent in all treatments, compared to the control.

Bio control agent Trichoderma harzianum along with potassium phosphonate has recorded highest disease suppression with least foliar yellowing (Srinivasan et al., 2003).

3. MATERIAL AND METHODS

The foregoing investigation comprised both field experiment and laboratory experiments, which were carried out during 2006-07 at Agricultural Research Station (Pepper), Sirsi, University of Agricultural Sciences, Dharwad.

Laboratory experiments were conducted at the College of Agriculture, Dharwad. A field experiment on integrated management of foot rot of black pepper (in arecanut plantation) was conducted during 2006, in a farmer’s garden at Hosabale village in Sirsi taluk of Uttara Kannada district of Karnataka. Sirsi is located in a hill zone of Karnataka 14° 35'N latitude and 74° 50'E longitude, at an altitude of 600 m MSL. The climate of this zone is humid tropical. The soil is lateritic with pH 5.5 to 5.8. This zone receives an average rainfall of 2500 mm from June to November. The temperature is around 24 to 27°C with maximum and minimum temperature of 36°C and 9°C respectively.

The details of the materials used and methods followed during the course of investigation are presented below.

3.1 SURVEY FOR DISEASE INCIDENCE, ISOLATION AND PROVING PATHOGENICITY

3.1.1 Survey for the disease incidence

A fixed plot survey was conducted to record the incidence of foot rot of black pepper caused by Phytophthora capsici Leonian emend, Alizedeh and Tsao during 2006 in three taluks of Uttara Kannada district, viz. Sirsi, Siddapur and Yellapur. In each taluk, 3 villages were selected. In each village, one garden was selected where black pepper vines were trained on live standards of arecanut and in each garden, 100 vines were randomly selected, to record observations like percentage leaf infection, foliar yellowing, defoliation, collar infection and wilting of vines.

3.1.2 Isolation and identification of pathogen

The standard tissue isolation technique (Tuite, 1969) was followed for isolation of pathogen from black pepper vines showing typical symptoms of foot rot disease. The samples were collected during 2006 from a farmer’s field of Mundigesara village during the survey. The infected tissues were cut into small pieces and surface sterilized with one per cent sodium hypochlorite for thirty seconds under aseptic conditions. Such bits were transferred into Petri dishes containing 20 ml of molten and cooled Potato Dextrose Agar (PDA) incorporated with pimaricin, vancomycin, pentachloronitrobenzene and hymaxazole and incubated at 20-25°C for five days.

P. capsici from soil underneath infected black pepper vines was obtained by following castor seed baiting technique (Narasimhan and Ramakrishnan, 1969). Viable castor seeds of variety GCH-4, 25 in number were surface sterilized and buried in 100 g of foot rot sick soil taken in 100 mm Petri plates. The soil moisture was maintained at field capacity. After incubation for 72 hours at 25±1°C, the castor seeds were removed from the soil. The soil particles on them were removed by washing in running tap water. Further, seeds were surface sterilized with one per cent sodium hypochlorite for two minutes and then washed in sterile distilled water for 2 to 3 times to remove traces of sodium hypochlorite and plated on 2 per cent agar after passing them once or twice over the flame. The growth obtained on seeds was examined to confirm the fungus as P. capsici and it was subcultured on oat meal agar slants and incubated at 25±1°C.

3.1.3 Maintenance of culture

P. capsici culture after purification by hyphal tip isolation method, was grown on oat meal agar and then transferred on to the slants of oat meal agar. The slants were incubated for five days at 25±1°C to allow the fungus to grow and were then stored at 22±1°C which served as stock culture. Later on, subculturing was done once in a month.

3.1.4 Study of pathogenicity

Sporangial suspension was used for the pathogenicity study. The method described by Riberio (1978) was followed for the production of sporangia. The sporangial suspension was made in a known amount of sterile distilled water (10

5 sporangia/ml) and was used for

inoculation to prove the pathogenicity.

Leaves of black pepper were inoculated with one ml of sporangial suspension by making little injury to them. Then they were kept in humid chamber. Root inoculation was done by making holes in soil around the root zones of rooted cuttings, raised in polythene bags and placing the sporangial suspension in them. Then they were observed for symptoms development on the cuttings.

3.2 ISOLATION AND EVALUATION OF NATIVE ANTAGONISTIC MICROORGANISMS

3.2.1 Isolation of antagonistic microorganisms from soil

Soil samples collected from root zone of healthy black pepper vines were pooled and representative samples were drawn. The fungal and bacterial bio-agents were isolated from representative sample by following the serial dilution technique as described below.

10 g of soil sample was transferred aseptically into 250 ml conical flask, containing 90 ml of sterilized distilled water and the contents were mixed properly by shaking for five minutes. 10 ml of aliquot was drawn and transferred to 90 ml water blank (containing sterile distilled water). The suspension was shaken for one minute, before it is further diluted. Further dilution 10

-2, 10

-3 and 10

-4 were obtained and used for isolation of fungal bioagents

and 10-4

and 10-5

for bacterial bioagents.

Twenty ml of molten media was poured in series of Petri plates. One ml of suspension from respective dilutions was transferred aseptically into Petri plates containing the medium separately. The plates were rotated manually for uniform distribution of the suspension in medium and were allowed to solidify. The plates were incubated at 27±1°C for seven days for development of fungal colonies. The colonies with characteristic growth of particular organisms were observed under microscope and growth from such colonies was subcultured on agar slants. The growths of fungal bioagents were further purified by hyphal tip culture. The culture obtained was compared with original description of the bioagents.

3.2.2 In vitro evaluation of native antagonistic microorganisms

Isolated fungal antagonists were evaluated by dual culture technique. The pathogen was inoculated on one side of the Petri plate filled with 20 ml of PDA and antagonist were inoculated at exactly opposite side of the same plate by leaving 3-4 cm gap. For this, actively growing five days old cultures were used. In case of bacterial antagonist evaluation, bacterial antagonists were streaked in the plates and fungal discs were inoculated. After a period of incubation, when the growth in control plate reached maximum (90 mm diameter), the radial growth of the pathogen was measured. Per cent inhibition over control was worked out according to the equation given by Vincent (1927).

C – T

I = ———— x 100

C

Where, I = Percent inhibition

C= Growth in control

T = Growth in treatment.

List of native antagonistic microorganisms isolated and tested against Phytophthora capsici were as follows

Sl. No. Antagonistic microorganisms

1 Bacillus sp. (Siddapur isolate)

2 Pseudomonas sp. (Siddapur isolate)

3 Pseudomonas sp. (Yellapur isolate)

4 Pseudomonas sp (Edahalli isolate)

5 Trichoderma sp. (Gudnapur isolate)

6 Trichoderma sp. (Siddapur isolate)

7 Trichoderma sp. (Yellapur isolate)

8 Trichoderma sp. (Mundigesara isolate)

9 Trichoderma sp. (Edahalli isolate)

10 Trichoderma harzianum (ARS, Sirsi)

11 Trichoderma harzianum (UAS, Dharwad)

3.3 IN VITRO EVALUATION OF BOTANICALS AND FUNGICIDES AGAINST Phytophthora capsici

3.3.1 In vitro evaluation of botanicals

Aqueous leaf extracts of some of the plant species were used to study their efficacy to inhibit the growth of Phytophthora capsici. A known quantity of leaf samples was crushed by adding equal quantity of sterilized distilled water separately. Garlic clove extract was also prepared by the same way. The extracts were added with streptomycin sulphate to avoid bacterial contamination.

Required quantity of individual botanicals was added separately into molten and cooled potato dextrose agar so as to get the desired concentrations of 5 or 10 per cent. Later, 20 ml of the poisoned medium was poured into sterilized Petri plates and the mycelium disk of 5 mm size from five days old cultures of P. capsici was cut out by a sterilized cork borer and one such disc was placed at the center of each agar plate. Control was maintained without adding any botanicals to medium. Four replications were maintained for each concentration. Then, such plates were incubated at room temperature for seven days and radial growth was measured when fungus attained maximum growth in control plates. The efficacy of the plant extracts was expressed as percent inhibition of mycelial growth over control, which was calculated by using the formula of Vincent (1927).

C – T

I = ———— x 100

C

Where, I = Percent inhibition

C= Growth in control

T = Growth in treatment.

The plant species selected for the evaluation of leaf extract for their efficacy to inhibit the growth of fungus were given below:

Sl.No. Common name Scientific name Plant parts used

1 Adusoge Adathoda vesica Nees Leaf

2 Clerodendron Clerodendron inerme G Leaf

3 Duranta Duranta plumeri Jacq. Leaf

4 Eupatorium Chromolaena odorata King. Leaf

5 Garlic (cloves) Allium sativum Linn. Cloves

6 Glyricidia Glyricidia maculata L. Leaf

7 Lokkisoppu Vitex nigundo L. Leaf

8 Lantana Lantana camera L. Leaf

9 Neem Azadirachta indica A.Juss Leaf

10 Tridax Tridax procumbens Linn. Leaf

3.3.2 In vitro evaluation of fungicides

The efficacy of nine fungicides at the concentrations of 0.1, 0.2 and 0.3 per cent was assayed in vitro using poisoned food technique (Falck, 1907).

Fungicides

Sl. No. Trade name /

Common name

Chemical name

1 Akomin Potassium phosphonate

2 Aliette 80 WP Fosetyl-Al 80% WP

3 Bordeaux mixture Copper sulphate + calcium hydroxide

4 Blitox COC 50% WP Copper oxychloride

5 Melody duo 66.75 WP Iprovalicarb 5.5% + Propineb 61.25%

6 Profiler 71.04 WDG Fluopicolide – 4.44% + Fosetyl – 66.66% WDG

7 Ridomil MZ 72 WP Metalaxyl 8% + Mancozeb 64% WP

8 Secure 60 WDG Fenamidone 10% + Mancozeb 50%

9 Verita 71 WDG Fenamidone 4.44% + Fosetyl 66.66%

Required quantity of individual fungicide was added separately into molten and cooled potato dextrose agar so as to get the desired concentrations of the fungicides. Later, 20 ml of the poisoned medium was poured into sterilized Petri plates. Mycelium disk of five mm size from five days old cultures of Phytophthora capsici was cut out by a sterilized cork borer and one such disc was placed at the center of each agar plate. Control treatment was maintained without adding any fungicide to the medium. Three replications were maintained for each concentration. After incubation for nine days at room temperature, radial growth was measured when fungus attained maximum growth in control plates. The efficacies of the fungicides were expressed as percent inhibition of mycelial growth over control, which was calculated by using the formula of Vincent (1927),

C – T

I = ———— x 100

C

Where, I = Percent inhibition

C= Growth in control

T = Growth in treatment.

3.4 SCREENING OF SEEDLINGS OF CULTIVATED BLACK PEPPER VARIETIES

Seeds of black pepper were collected from healthy vines of nine cultivated black pepper varieties, viz. Karimalligesara, HP-812, P-24, OP-Karimunda, HP-34, HP-813, OP-KM-2, Panniyur-1 and Mannikoppa. Foot rot disease sick soil was prepared by adding the roots, stems and leaves of vines affected by foot rot disease. Thus obtained sick soil was filled into pots. Five hundred seeds of different varieties were sown in the pots containing disease sick soil. Each variety was replicated thrice.

Moisture in these pots was kept at optimum level by frequent watering. Number of seeds germinated in each pot was recorded. After germination, leaves infected by P. capsici were placed around the seedlings regularly. This supplied the necessary inoculum throughout the experimental period. In each pot, number of plants collapsed was recorded at frequent intervals.

3.5 INTEGRATED MANAGEMENT OF PHYTOPHTHORA FOOT ROT OF BLACK PEPPER

A field experiment on management of foot rot of black pepper by using chemicals, biological agents and plant product like neem cake was carried out in a farmer’s garden at Hosabale village during 2006-07. Integrated disease management of foot rot of black pepper was carried using Randomized Complete Block Design (RCBD). The treatment details are given below. In each treatment, 20 pepper vines were selected. The treatments were taken as premonsoon and peak monsoon application, in May-June and in the month of August-September respectively.

3.5.1 Application of neem cake

Finely powder neem cake was incorporated into top 10 cm layer of soil around the vines at 1 kg/vine during the month of May 2006.

3.5.2 Application of biocontrol agents

Trichoderma harzianum was mass multiplied on moist wheat bran preparations (1:1 v/v) (Jahagirdar, 1998). It was added to soil at rate of 50 g of preparation per vine. Pseudomonas fluorescens was mass multiplied on King’s B broth (Sivamani and Gnanamanicum, 1988) (and the cell count was adjusted to 10

8 cells/ml) and the biocontrol

agent was diluted in 3 l of water and then applied to the vine as soil application.

3.5.3 Application of fungicides

The fungicides, viz. Potassium phosphonate (0.3%), Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (0.125%), Bordeaux mixture (1%), Copper oxychloride (0.2%) and Copper hydroxide (Kocide) (0.2%) were applied as drench and spray along with biocontrol agents either alone or in combination.

3.5.4 Field observations on integrated management of foot rot of black pepper

3.5.4.1 Leaf infection

Number of vines showing leaf infection was recorded and presented as per cent leaf infection. For intensity of leaf infection, three areas (0.5 sq. m.) randomly selected in the

canopy of black pepper vines, preferably each at lower level, middle level and upper level of the canopy and number of leaves present and number of leaves infected by the disease were recorded and presented as per cent leaves infested by the disease (Anonymous, 2004).

3.5.4.2 Defoliation

Number of vines showing defoliation was recorded and presented as per cent defoliated vines. For intensity of defoliation, grades were given based on visual observation using following scale, preferably at lower level middle level and upper level and presented as defoliation index (Anonymous, 2004).

Index Defoliation

0 Nil

1 Upto 25%

2 25 to 50%

3 More than 50%

3.5.4.3 Foliar yellowing

Number of vines showing foliar yellowing was recorded and presented as per cent foliar yellowing of vines. For intensity of foliar yellowing, grade were given based on visual observation using following scale, preferably at lower level, middle level and upper level and presented as foliar yellowing index (Anonymous, 2004).

Index Foliar yellowing

0 Nil

1 Upto 25%

2 25 to 50%

3 More than 50%

3.5.4.4 Collar infection and wilting of vines

Number of vines showing collar infection and wilted vines were recorded and presented as per cent collar infected vines and per cent wilted vines.

Treatment details

Treatment No. Details

T1 Potassium phosphonate (3 ml l-1

), spray + drench

T2 Potassium phosphonate (3 ml l-1

), spray + drench + Trichoderma harzianum (50 g vine

-1) + Pseudomonas fluorescens (100 ml vine

-1) as

soil application + neem cake (1 kg vine-1

)

T3 Ridomil MZ 72 WP (1.25 g l-1

) as spray + drench

T4 Ridomil MZ 72 WP (1.25 g l-1

) as spray + drench + Trichoderma harzianum (50 g vine

-1) + Pseudomonas fluorescens (100 ml vine

-1) as

soil application + neem cake (1 kg vine-1

)

T5 Trichoderma harzianum (50 g vine-1

) + Pseudomonas fluorescens (100 ml vine

-1) as soil application + P. fluorescens as spray (1%)

T6 Bordeaux mixture (1%) spray + copper oxychloride (2 g l-1

) drench

T7 Copper hydroxide (2 g l-1

) spray + drench

T8 Untreated control

3.5.5 Media used for isolation of soil antagonistic microorganisms

Potato dextrose agar (for fungi)

Potato – 100 g

Dextrose – 20 g

Agar – 20 g

Distilled water – 1000 ml

pH – 7.0

Nutrient agar (for bacteria)

Glucose – 5.00 g

Peptone – 5.00 g

Beef extract – 3.00 g

Agar – 20.00 g

Distilled water – 1000 ml

pH of medium – 7.2

Medium for isolation of Trichoderma spp.

Magnesium sulphate (MgSO4.7H2O) – 0.2 g

K2HPO4 – 0.9 g

Ammonium nitrate (NH4NO3) – 1.0 g

Potassium chloride (KCl) – 0.5 g

Glucose (C6H12O6) – 3.0 g

Agar – 15.0 g

Metalaxyl MZ – 0.3 g

Rose Bengal – 0.15 g

Chlorophenical – 0.25 g

Distilled water – 1000 ml

pH was adjusted to – 6.0

King’s B medium (for Pseudomonas sp.)

Peptone – 20 g

K2HPO4 – 1.5 g

MgSO4 – 1.5 g

Glycerol – 10.0 ml

Agar – 15.0 g

Distilled water – 1000 ml

Cyclohexamide – 100 ppm

Amplicillin – 50 ppm

Chlorophenical – 12.5 ppm

4. EXPERIMENTAL RESULTS

The results of the investigation entitled “Studies on foot rot of black pepper caused by Phytophthora capsici Leon.” undertaken during 2006-07 is presented hereunder.

4.1 SURVEY FOR THE INCIDENCE AND DISTRIBUTION OF FOOT ROT OF BLACK PEPPER

Fixed plot survey was conducted during pre-monsoon, peak monsoon and post monsoon seasons of 2006-07 in the three taluks of Uttar Kannada district, viz. Sirsi, Siddapur and Yellapur. The survey was conducted with an objective to assess the incidence and distribution of foot rot of black pepper on cultivated varieties. The observations were presented in Table 1, 2 and 3.

4.1.1 Disease incidence during pre-monsoon season

The average maximum leaf infection (9.13%) was recorded in Siddapur taluk while least leaf infection (6.42%) was observed in Sirsi taluk. Among the different places surveyed, Siddapur and Tarakanahalli locations recorded maximum (9.30%) and minimum (2.60%) leaf infection, respectively. Foliar yellowing intensity also more in case of Siddapur taluk and least intensity noticed in Yellapur taluk. Maximum (11.20%) foliar yellowing was observed at Tarakanahalli and least at Edahalli village (4.23%) of Sirsi taluk. The mean maximum defoliation (21.23%), collar infection (10.24%) and wilting of vines (9.67%) was recorded in Sirsi taluk and mean minimum defoliation (8.93%) and collar infection (6.46%) in Yellapur taluk and wilted vines (6.06%) were recorded in Siddapur taluk. Maximum defoliation (31.20%), collar infection (21.30%) and wilting of vines (20.50%) were recorded at Mundigesara village of Sirsi taluk whereas minimum collar infection (5.20%) and wilted vines (3.40%) at Tarakanahalli of Sirsi taluk (Table 1).

4.1.2 Disease incidence during peak-monsoon season

During peak monsoon (July-August) season, leaf infection (31.17%) and foliar yellowing (36.83%) were higher at Sirsi taluk and least leaf infection (27.53%) and foliar yellowing (34.17%) were recorded in Siddapur and Yellapur taluks, respectively. Highest leaf infection of 46.60 per cent and foliar yellowing of 60.00 per cent were observed at Mundigesara village of Sirsi taluk. Mean maximum (40.70%) and minimum (39.60%) defoliation were recorded in Yellapur and Sirsi taluk, respectively.

Average collar infected and wilted vines percentage ranged from 18.40 to 50.00 and 14.32 and 41.30 during peak monsoon season, respectively. Highest collar infected (29.56%) and wilting of vines (23.53%) was recorded in Siddapur taluk. Among the nine locations surveyed, Mundigesara village of Sirsi taluk recorded highest collar infection of 50.00 per cent and wilted vines of 39.20 per cent (Table 2).

4.1.3 Disease incidence during post-monsoon season

In the post monsoon season, leaf infection percentage was higher in Sirsi taluk (19.80%) yellowing (22.16%) and defoliation (23.80%) was higher in Yellapur taluk. Mean minimum leaf infection (12.10%), foliar yellowing (18.10%) and defoliation (23.41%) were recorded in Yellapur, Siddapur and Sirsi taluks respectively. Leaf infection ranged from 14.60 to 25.00 per cent, foliar yellowing ranged from 13.80 to 24.20 per cent and defoliation ranged from 16.30 to 28.30 per cent during the post monsoon season.

The average maximum collar infection (36.35%) and wilted vines (27.63%) were recorded in Siddapur taluk while minimum collar infection (27.16%) and wilted vines (25.20%) in Yellapur taluk (Table 3).

4.2 SYMPTOMATOLOGY

The black pepper vines cultivated as an intercrop in arecanut plantations succumbed to infection of foot rot during monsoon season. The natural infection of pepper vines was observed for the sequential development of symptoms. The pathogen Phytophthora capsici caused infection in all parts of the vine i.e. stems, leaves, collar, root, spikes and berries. The general disease symptoms are described in the following paragraphs.

Table 1. Incidence of foot rot of black pepper during pre-monsoon season (May-June) 2006-07

Taluk Villages Leaf

infection (%)

Foliar yellowing

(%)

Defoliation (%)

Collar infection

(%)

Wilted vines (%)

Edahalli 8.47 4.23 15.30 4.23 5.10

Tarakanahalli 2.60 11.20 17.20 5.20 3.40

Mundigesara 8.19 8.19 31.20 21.30 20.50

Sirsi

Mean 6.42 7.87 21.23 10.24 9.67

Kantur 9.10 7.40 12.40 6.70 5.90

Siddapur 9.30 8.40 13.50 7.40 7.40

Nanikatte 8.90 8.10 11.30 6.50 4.90

Siddapur

Mean 9.13 7.96 12.4 6.86 6.06

Yellapur 8.10 5.70 9.00 6.60 5.70

Bairumbe 7.00 6.10 7.80 6.10 7.80

Manchikere 8.30 8.30 10.00 6.70 7.50

Yellapur

Mean 7.80 6.70 8.93 6.46 7.00

Table 2. Incidence of foot rot of black pepper during peak-monsoon season (July-August) 2006-07

Taluk Villages Leaf

infection (%)

Foliar yellowing

(%)

Defoliation (%)

Collar infection

(%)

Wilted vines (%)

Edahalli 29.80 30.5 33.00 23.20 19.00

Tarakanahalli 20.40 24.50 24.50 20.40 18.60

Mundigesara 46.60 60.00 61.60 50.00 39.20

Sirsi

Mean 31.17 36.83 39.60 29.17 22.43

Kantur 45.40 52.10 35.50 20.30 41.30

Siddapur 17.10 29.30 60.30 50.00 14.30

Nanikatte 20.00 20.00 24.20 18.40 15.00

Siddapur

Mean 27.53 35.30 40.10 29.56 23.53

Yellapur 24.20 27.50 35.00 18.40 16.70

Bairumbe 32.00 39.20 45.6 24.00 24.00

Manchikere 32.50 35.80 41.50 21.90 18.70

Yellapur

Mean 29.57 34.17 40.70 21.43 19.80

Table 3. Incidence of foot rot of black pepper during Post-monsoon season (October-

November) 2006-07

Taluk Villages Leaf

infection (%)

Foliar yellowing

(%)

Defoliation (%)

Collar infection

(%)

Wilted vines (%)

Edahalli 19.80 23.90 25.60 27.50 24.50

Tarakanahalli 14.60 13.80 16.30 17.10 10.60

Mundigesara 25.00 24.20 28.30 60.00 41.30

Sirsi

Mean 19.80 20.63 23.41 34.87 25.46

Kantur 14.60 17.80 21.90 24.20 45.40

Siddapur 16.00 20.00 26.40 50.00 17.10

Nanikatte 15.70 16.50 22.30 23.20 20.40

Siddapur

Mean 15.43 18.10 23.53 36.35 27.63

Yellapur 17.10 22.80 25.20 24.00 21.90

Bairumbe 15.30 23.40 23.40 32.50 30.50

Manchikere 16.30 20.30 22.80 25.00 23.20

Yellapur

Mean 12.10 22.16 23.80 27.16 25.20

Initial infection on leaves of runner shoots

Plate 1. Symptoms of Phytophthora foot rot of black pepper on different parts

Plate 2. Pathogenicity test of Phytophthora capsici

Plate 3. Pathogenicity test of Phytophthora capsici

The first visible symptoms of the disease were observed on the leaves of runner shoots which are close to the soil surface during first week of July i.e. about one month after the onset of the south west monsoon. The temperature was 22.2°C with 91.9 per cent relative humidity during the disease development under natural conditions. Infected leaves developed water soaked lesions and rapidly expanded into dark brown spots with fimbriate margin. The leaf infection gradually spread to a height of 12 to 15 feet. Later, such black pepper vines defoliated severely. Water soaked brown lesions appeared on the stem of the vines which gradually turned to dark brown in a short period of 48 to 72 hours. The leaves of the vines became flaccid and yellow. Later, such vines resulted in severe rotting of tissues. There was cracking and breaking of the twigs from the main stem at nodal region.

In the collar region, the infection started as slimy dark patch. Later, the vines showed the synchronized effect of yellowing of foliage, flaccidity, defoliation, breaking and vascular discolouration at nodal region of stem, spike shedding and berry dropping. The infection progressed both upwards and also downwards.

The root infection in the black pepper vine started in feeder roots. Gradually, the infection progressed to collar region and resulted in death of the vine. The symptom expression of the black pepper vines due to collar infection was similar for root infection. Sudden wilting and death of the vine due to collar and root infection were rampant during post monsoon season i.e. October to December.

4.3 ISOLATION

Isolation of P. capsici from the infected black pepper leaves, stem and roots was made successfully on oat meal agar medium supplemented with pimaricin, vancomycin, pentachloronitrobenzene and hymaxazole as explained in ‘Materials and Methods’. The culture was purified by hyphal tip isolation on two per cent agar. Castor seeds, baited in soil samples collected from the root zone of infected black pepper vines invariably yielded P. capsici.

4.3.1 Pathogenicity

4.3.1.1 Leaf inoculation

The leaves of black pepper when inoculated with 0.1 ml sporangial suspension drawn from an aliquot containing 10

5 sporangia/ml of P. capsici developed water soaked lesions

after incubation for 48 hours. The lesions were dark, circular to irregular in shape which enlarged and covered the entire leaf area when the relative humidity was maintained above 90 per cent.

4.3.1.2 Root inoculation

Rooted cuttings of black pepper were inoculated with sporangial suspension (2 ml, each containing 10

5 sporangia/ml) of P. capsici as explained in ‘Material and Methods’. The

wilting of cuttings was observed after eight days of inoculation.

4.4 ISOLATION AND IN VITRO EVALUATION OF NATIVE ANTAGONISTIC MICROORGANISMS

An attempt was made to isolate and establish antagonistic potential of native antagonists in view of their rhizosphere competency and ubiquitous nature. Isolates were obtained from rhizosphere of black pepper vines using specific media mentioned earlier. Fungal and bacterial antagonists obtained were evaluated to know their antagonistic efficacy, for their further use in integrated disease management. Results of mycelial inhibition of test pathogen P. capsici are explained hereunder.

Per cent mycelial inhibition of P. capsici over control under in vitro condition ranged from 2.02 to 58.41 per cent. Significantly, highest inhibition of radial growth of mycelia of P. capsici was recorded in (T8) Trichoderma sp. of Mundigesara isolate (58.41%) isolate which was on par with (T7) Trichoderma sp. of Yellapur isolate (56.76%). Trichoderma sp. of Gudnapur (52.71%), Edahalli (52.27%) and Siddapur (50.53%) have also recorded a considerable level of inhibition of mycelial growth of P. capsici and which were on par with each other (Table 4).

Table 4. In vitro evaluation of native microbial antagonists against Phytophthora

capsici

Sl. No. Microbial antagonists Per cent mycelial inhibition

1 Bacillus sp. (Siddapur) 9.62

(18.06)

2 Pseudomonas sp. (Siddapur) 12.96

(21.09)

3 Pseudomonas sp. (Yellapur) 0.37

(2.02)

4 Pseudomonas fluorescens (Edahalli) 15.19

(22.92)

5 Trichoderma sp.(Gudnapur) 63.33

(52.71)

6 Trichoderma sp. (Siddapur) 59.62

(50.53)

7 Trichoderma sp.(Yellapur) 69.99

(56.76)

8 Trichoderma sp.(Mundigesara) 72.59

(58.41)

9 Trichoderma sp. (Edahalli) 62.59

(52.27)

10 Trichoderma harzianum (ARS, Sirsi) 57.04

(49.02)

11 Trichoderma harzianum (UASD) 55.92

(48.38)

S.Em. ± 0.659

CD at 1% 2.608

* Figures in parenthesis are arcsine transformed values

0

10

20

30

40

50

60

70

80

Bac

illus

sp.

(Sid

dapu

r)

Pse

udom

onas

sp.

(Sid

dapu

r)

Pse

udom

onas

sp.

(Yel

lapu

r)

Pse

udom

onas

flur

osce

ns (E

daha

lli)

Tric

hode

rma

sp.(G

udna

pur)

Tric

hode

rma

sp.

(Sid

dapu

r)

Tric

hode

rma

sp.(Y

ella

pur)

Tric

hode

rma

sp.(M

undi

gesa

ra)

Tric

hode

rma

sp.

(Eda

halli

)

Tric

hode

rma

harz

ianu

m (A

RS

, Sirs

i)

Tric

hode

rma

harz

ianu

m (U

AS

D)

Fig. 1. In vitro evaluation of native microbial antagonists against Phytophthora capsici

Fig. 1. In vitro evaluation of native microbial antagonists against Phytophthora capsici

Plate 4. In vitro evalution of native microbial antagonists against Phytophthora capsici

Trichoderma harzianum from ARS, Sirsi (49.02%) and T. harzianum from UAS, Dharwad (48.38%) were also significantly superior to control and were on par with each other. Least inhibition of mycelial growth of P. capsici was recorded in Pseudomonas sp. of Yellapur isolate (2.02%). Among bacterial antagonists, highest mycelial inhibition was recorded in P. fluorescens of Edahalli village (22.92%) followed by Pseudomonas sp. (Siddapur) (21.09%) which were on par with each other (Table 4).

4.5 IN VITRO EVALUATION OF BOTANICALS AND FUNGICIDES ON Phytophthora capsici

4.5.1 In vitro evaluation of botanicals against Phytophthora capsici

Plant extracts of ten locally available plant species were evaluated against the growth of P. capsici as described in ‘Material and Methods’. The results obtained are presented in Table 5.

Among the ten plant extracts tested, highest per cent mycelial inhibition of P. capsici was observed in garlic cloves extract (28.87%) at five per cent concentration. It was followed by lantana (27.33%), eupatorium (25.47%) and neem (24.07%). Plant extracts of Duranta (18.06%) and Lakkisoppu (18.40%), Adusoge (7.73%) and Glyricidia (6.89%) were at par with each other. Least inhibitory effect was recorded in tikki weed (0.00%) at five per cent concentration.

At higher concentration (10%) also, cloves extract of garlic (36.58%) recorded highest inhibition of radial growth of mycelia. It was followed by duranta (31.07%), eupatorium (30.83%), neem (30.10) and lantana (30.09%) which were on par with each other. Least mycelial inhibition was recorded in Adusoge (21.09%) and tikki weed (22.61%).

Though all the plant extracts recorded the inhibition of radial growth of mycelia of P. capsici to certain extent, their inhibitory effect on radial growth of mycelia increased with increase in concentration. Garlic cloves extract recorded highest inhibition at both the concentration and found most effective.

4.5.2 Efficacy of fungicides against P. capsici

The data on different fungicides screened in vitro at three concentrations and their per cent mycelial inhibition over control are presented in Table 6 and Fig. The cent per cent mycelial inhibition was recorded with fungicides, viz. Akomin, Melody duo, Ridomil MZ 72 WP and Secure at all the three concentrations (0.1%, 0.2% and 0.3%), Aliette and Bordeaux mixture also recorded cent per cent inhibition of radial growth of mycelia of P. capsici at 0.3 per cent concentration. Mean minimum per cent mycelial inhibition was observed with fungicides Verita (51.25%) and Copper oxychloride (60.26%). However, all the fungicides screened in vitro against P. capsici at three different concentrations were significantly superior to control and significantly differed with each other.

4.6 SCREENING OF BLACK PEPPER SEEDLINGS AGAINST Phytophthora capsici

Seedlings raised from seeds of nine cultivated varieties were screened for their resistance against P. capsici as described earlier in ‘Material and Methods’. The results obtained are presented hereunder (Table 7).

The maximum per cent germination was noticed in the variety P-24 (76.6%). This was followed by hybrid HP-34 (72.4%) and a local variety Mannikoppa (71.0%). Minimum per cent germination was recorded in OP-Karimunda (63.0%) and Karimunda (63.8%). In the present study, all the seedlings in every variety showed the symptoms of P. capsici infection and were found susceptible. Though there was difference among the varieties in time taken for first appearance of symptoms to the death of seedlings, hundred per cent death of seedlings observed in all the varieties tested.

Table 5. In vitro evaluation of plant extracts against Phytophthora capsici

Per cent mycelial

inhibition

Concentrations

Sl. No.

Common name

Botanical name Plant parts used

5% 10%

Mean

1 Adusoge Adathoda vesica Nees Leaf 1.85

(7.73)

12.96

(21.09)

7.40

(14.41)

2 Baad Clerodendron inerme G Leaf 12.96

(21.06)

22.96

(28.61)

17.96

(24.85)

3 Duranta Duranta plumeri Jacq. Leaf 9.62

(18.06)

26.66

(31.07)

18.14

(24.56)

4 Eupatorium Chromolaena odorara King.

Leaf 18.51

(25.47)

26.29

(30.83)

22.40

(28.15)

5 Garlic Allium sativum Linn. Cloves 23.33

(28.87)

35.55

(36.58)

29.44

(32.72)

6 Glyricidia Glyricidia maculata L. Leaf 1.48

(6.89)

21.85

(27.86)

11.66

(17.37)

7 Lakkisoppu Vitex nigundo L. Leaf 9.99

(18.40)

21.11

(27.33)

15.55

(22.87)

8 Lantana Lantana camera L. Leaf 21.11

(27.33)

25.18

(30.09)

23.14

(28.71)

9 Neem Azadiracta indica A.Juss Leaf 16.66

(24.07)

25.18

(30.10)

20.92

(27.09)

10 Tikki weed Tridax procumbens Linn. Leaf 0.00

(0.00)

14.81

(22.61)

7.40

(11.31)

Mean 16.17 26.02 21.09

S.Em. ± CD at 1 %

Plant extract (P)

Concentration(C)

Interaction (P X C)

0.366

0.156

0.517

1.393

0.954

1.970

* Figures in parenthesis are arcsine transformed values

0

5

10

15

20

25

30

35

40

Adu

soge

Baa

d

Dur

anta

Eup

ator

ium

Gar

lic

Gly

ricid

ia

Lakk

isop

pu

Lant

ana

Nee

m

Tikk

i wee

d

5% 10%

Fig. 2. In vitro evaluation of plant extracts against Phytophthora capsici

Fig. 2. In vitro evaluation of plant extracts against Phytophthora capsici

Plate 5. In vitro evaluation of plant extracts against Phytophthora capsici

4.7 INTEGRATED MANAGEMENT PHYTOPHTHORA FOOT ROT OF BLACK PEPPER

The field experiment on integrated management of foot rot of black pepper was conducted in a farmer’s field at Hosabale village, Sirsi taluk. The treatment details were given in material and methods in each treatment 20 black pepper vines were selected. The treatments were given twice during May-June and July-August. The observations on leaf infection, foliar yellowing, defoliation, collar infection and wilted vines were recorded at monthly intervals as explained earlier in the material and methods.

4.7.1 Leaf infection (%)

During June, leaf infection percentages were not significantly differs over the treatments. All the treatments viz., Potassium phosphonate (3 ml l

-1) spray with drench (T1),

Potassium phosphonate (3 ml l-1

) spray with drench integrated with Trichoderma harzianum (50 g/vine), Pseudomonas fluorescens (100 ml vine

-1) and neem cake (1 kg vine

-1) (T2),

Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1 ml l-1

) spray with drench (T3), Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) spray with drench integrated with T. harzianum, P. fluorescens and neem cake (T4), T. harzianum (50 g vine

-1) and P. fluorescens (100 ml vine

-1) soil application

along with foliar spray of P. fluorescens (1%), (T5), Bordeaux mixture (1%) spray with Copper oxychloride (2 g l

-1) drench (T6), Copper hydroxide (2 ml l

-1) spray with drench (T7) and control

(T8) treatments were on par with each other.

During July month, lower leaf infection was observed in the treatments Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (spray and drench) integrated with bioagents T. harzianum and P. fluorescens and plant product neem cake (T4) (8.92%) which is significantly differ over control (30.56%) and all other treatments. Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) with bio-agents and plant product (T4) was followed by Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) spray followed by drench (T3) (18.34%) which was on par with the Potassium phosphonate (spray and drench) in combination with bioagents T. harzianum, P. fluorescens and plant product neem cake (T2) (18.87%) and Potassium phosphonate alone as spray and drench (T1) (19.74%). High leaf infection intensity was observed in control (30.56%), chemical Copper hydroxide alone as spray and drench (T7) (26.19%) and bio-agents alone T. harzianum and P. fluorescens as soil application along with P. fluorescens (1%) spray (T5) (23.43%). Bordeaux mixture spray with Copper oxychloride drench was recorded 21.43 per cent of leaf infection.

During August month, least leaf infection was recorded in the treatment Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray and drench integrated with bioagents T. harzianum, P. fluorescens and plant product neem cake (T4) (11.66%) which was followed by Potassium phosphonate combined with T. harzianum, P. fluorescens and neem cake (18.81%). The chemicals Potassium phosphonate (21.56%) and Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (20.62%) as spray and drench were on par with each other. Highest leaf infection intensity was recorded in untreated vines (38.02%) followed by chemical Copper hydroxide spray and drench (T7) (32.07%), bioagents T. harzianum, P. fluorescens as soil application along with foliar spray of P. fluorescens (T5) (28.08%) and Bordeaux mixture as spray with Copper oxychloride drench (T6) (25.32%).

During September month, least leaf infection was recorded with Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) spray and drench followed by bioagents T. harzianum, P. fluorescens and plant product neem cake (T4) (10.69%). Leaf infection was maximum in untreated pepper vines (T8) (44.68%) followed by Copper hydroxide spray with drench (T7) (31.22%). Leaf infection was found on par in the treatments Potassium phosphonate (T1) (19.17%) and Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (T3) (16.91%) as spray with drench and Potassium phosphonate spray and drench along with bioagents T. harzianum, P. fluorescens and plant product neem cake (T3) (17.68%).

Table 6. Bioassay of fungicides against Phytophthora capsici causing foot rot of black pepper

Per cent mycelial inhibition

Concentrations Sl. No.

Fungicides

0.1 % 0.2 % 0.3%

Mean

1 Akomin 100

(89.96)

100

(89.96)

100

(89.96)

100

(89.96)

2 Aliette 80 WP 74.08

(59.37)

78.15

(62.11)

100

(89.96

84.08

(70.48)

3 Boudreaux mixture 66.30

(54.49)

72.22

(58.17)

100

(89.96

79.51

(67.54)

4 Blitox COC 50% WP 71.11

(57.46)

77.41

(61.60)

79.30

(62.92)

75.94

(60.26)

5 Melody duo 66.75 WP 100

(89.96)

100

(89.96)

100

(89.96)

100

(89.96)

6 Profiler 71.04 WDG 77.41

(61.60)

84.44

(66.74)

85.56

(66.75)

82.47

(65.33)

7 Ridomil MZ 72 WP 100

(89.96)

100

(89.96)

100

(89.96)

100

(89.96)

8 Secure 60 WDG 100

(89.96)

100

(89.96)

100

(89.96)

100

(89.96)

9 Verita 71 WDG 49.63

(44.77)

64.44

(53.37)

68.52

(55.85)

60.86

(51.25)

Mean 63.75 66.19 72.62 67.57

S.Em. ± CD at 1%

Fungicide (F)

Concentration(C)

Interaction (F X C)

0.129

0.068

0.224

0.486

0.254

0.842

* Figures in parenthesis are arcsine transformed values

0

10

20

30

40

50

60

70

80

90

100

Ako

min

Alie

tte 8

0 W

P

Bou

rdea

ux m

ixtu

reB

litox

CO

C 5

0% W

PM

elod

y du

o 66

.75

WP

Pro

filer

71.

04 W

DG

Rid

omil

MZ

72 W

P

Sec

ur 6

0 W

DG

Ver

ita 7

1 W

DG

0.10% 0.20% 0.30%

Fig. 3. Bioassay of fungicides against Phytophthora capsici causing foot rot of black pepper

Fig. 3. Bioassay of fungicides against Phytophthora capsici causing foot rot of black pepper

Plate 6. Bioassary of fungicides against Phytophthora capsici

Table 7. Screening of black pepper varieties against Phytophthora capsici

Sl. No.

Variety Number of seeds

sown Number of seeds

germinated Germination (%)

Number of seedlings died

Per cent mortality

1 Karimalligesara 500 336 67.2 336 100

2 HP-34 500 362 72.4 362 100

3 HP-812 500 349 69.8 349 100

4 HP-813 500 343 68.6 343 100

5 Karimunda 500 315 63.8 315 100

6 OP-Karimunda 500 319 63.0 319 100

7 Panniyur-1 500 327 65.4 327 100

8 P-24 500 383 76.6 383 100

9 Mannikoppa 500 355 71.0 355 100

Plate 7. Screening of black pepper varieties against

Table 8. Incidence of leaf infection (%) in integrated management of foot rot of black pepper

Tr. no.

Treatment details June July August September October

T1 Potassium phosphonate (3 ml l-1

), spray + drench 1.17 (6.18)

11.42 (19.74)

13.52 (21.56)

10.84 (19.17)

9.24 (17.68)

T2 Potassium phosphonate (3 ml l-1

), spray + drench + Trichoderma harzianum (50 g vine

-1) + Pseudomonas fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

1.34 (6.60)

10.50 (18.87)

10.42 (18.81)

9.24 (17.68)

5.97 (14.13)

T3 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench 1.26 (6.41)

9.91 (18.34)

12.43 (20.62)

8.48 (16.91)

3.69 (11.05)

T4 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench + T. harzianum (50 g vine

-1) + P. fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

1.59 (7.18)

2.44 (8.92)

4.12 (11.66)

3.45 (10.69)

2.44 (8.94)

T5 T. harzianum (50 g vine-1

) + P. fluorescens (100 ml vine-1

) as soil application + P. fluorescens as spray (1%)

1.59 (7.10)

16.21 (23.43)

22.17 (28.08)

21.00 (27.26)

15.96 (23.54)

T6 Bordeaux mixture (1%) spray + copper oxychloride (2 g l-1

) drench 1.85 (7.76)

13.36 (21.43)

18.31 (25.32)

16.30 (23.79)

12.43 (20.63)

T7 Copper hydroxide (2 g l-1

) spray + drench 1.42 (6.80)

19.49 (26.19)

28.22 (32.07)

26.88 (31.22)

25.70 (30.45)

T8 Untreated control 1.68 (7.41)

25.87 (30.56)

37.97 (38.02)

49.48 (44.68)

52.92 (46.66)

Mean 1.49 (6.16)

13.65 (18.64)

18.40 (21.79)

18.21 (21.27)

15.58 (19.23)

S.Em. ± 0.595 0.495 0.513 0.686 0.450

CD @ 5 % 1.804 1.503 1.557 2.082 1.229

* Figures in parenthesis are arcsine transformed values

0

10

20

30

40

50

60

T1 T2 T3 T4 T5 T6 T7 T8

June July August September October

Fig. 4. Incidence of leaf infection (%) in integrated management of Phytophthora foot rot of black pepper

Fig. 4. Incidence of leaf infection (%) in integrated management of Phytophthora foot rot of black pepper

During October month, least leaf infection was observed with the Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) application as spray and drench along with the application of T. harzianum, P. fluorescens and neem cake (T4) (8.94%). It was followed by Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) alone as spray and drench (T3) (11.05%) and Potassium phosphonate as spray and drench in combination with T. harzianum, P. fluorescens and neem cake (T2) (14.13%). Maximum leaf infection was recorded in untreated vines (T8) (46.66%) (Table 8).

4.7.2 Yellowing index (%)

During June, yellowing index was lower in treatment T5 (29.37%) having T. harzianum and P. fluorescens soil application along with foliar spray of P. fluorescens which was on par with the Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) spray and drench (T3) (29.64%). They were followed by Potassium phosphonate spray with drench (T1) (31.67%). Potassium phosphonate integrated with bioagents T. harzianum, P. fluorescens and plant product neem cake as soil application (T2) (34.62%), Copper hydroxide spray with drench (T7) (33.48%) and Bordeaux mixture spray with Copper oxychloride drench (T6) (32.96%) treatments were on par with each other. The higher yellowing index was recorded in the treatment Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) combined with bioagents T. harzianum, P. fluorescens and the plant product neem cake as soil application (T4) (36.37%) which was on par with control treatment (T8) (35.87%).

During July, least yellowing index was observed in the treatment Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (spray and drench) combined with bioagents T. harzianum, P. fluorescens and plant product neem cake (T4) (1.50%) which was on par with Potassium phosphonate (spray and drench) in combination with T. harzianum, P. fluorescens and neem cake (T2) (2.20%) and Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) alone as spray and drench (T3) (2.60%). Untreated black pepper vine were recorded highest yellowing index (23.38%). Potassium phosphonate as spray and drench (T1) with respect to yellowing index (10.44%) was on par with T. harzianum and P. fluorescens as soil application followed P. fluorescens (1%) as foliar spray (T5) (11.69%) and Bordeaux mixture (1%) as spray with Copper oxychloride as soil drench (T6) (16.22%) was on par with Copper hydroxide as spray with drench (T7) (17.70%).

During August month also, yellowing index was also least with Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) in combination with T. harzianum, P. fluorescens and neem cake (T4) (3.63%). It was followed by potassium phosphonate along with T. harzianum, P. fluorescens and neem cake (T2) (10.08%), Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) alone as spray followed by drench (T3) (13.86%) and Potassium phosphonate alone as spray and drench (T1) (15.54%). Maximum yellowing index was observed in untreated black pepper vines (T8) (31.78%) and Copper hydroxide (T7) (25.92%).

During September month, yellowing index was least in the treatment Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) spray and drench along with bioagents T. harzianum, P. fluorescens and plant product neem cake (T4) (6.85%) and it was followed by Potassium phosphonate along with bioagents and neem cake (T2) (13.62%) and Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) alone as spray and drench (T3) (19.18%). All the treatments were significantly differ over the control.

During October, yellowing index was minimum (5.98%) in the treatment Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) application along with T. harzianum, P. fluorescens and neem cake (T4). It was followed by Potassium phosphonate combined with T. harzianum, P. fluorescens and neem cake (T2)(14.85%) and Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (T3) (20.70%) alone as spray and drench. Maximum yellowing index was observed in untreated vines (T8) (52.38%)(Table 9).

4.7.3 Defoliation index (%)

During June, defoliation index was higher in the treatment having Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) with bioagents T. harzianum, P. fluorescens and plant product neem cake as soil application (T4) (37.23%) which was significantly differ over other treatments. All the treatments except T4 were on par with each other and also with control treatment.

Table 9. Incidence of yellowing index (%) in integrated management of foot rot of black pepper

Tr. no.

Treatment details June July August September October

T1 Potassium phosphonate (3 ml l-1

), spray + drench 29.59 (31.67)

3.29 (10.44)

7.20 (15.54)

15.43 (23.11)

22.63 (28.38)

T2 Potassium phosphonate (3 ml l-1

), spray + drench + Trichoderma harzianum (50 g vine

-1) + Pseudomonas fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

32.30 (34.62)

0.41 (2.20)

3.09 (10.08)

5.56 (13.62)

6.58 (14.85)

T3 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench 24.49 (29.64)

0.62 (2.60)

5.76 (13.86)

10.80 (19.18)

12.55 (20.70)

T4 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench + T. harzianum (50 g vine

-1) + P. fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

35.19 (36.37)

0.21 (1.50)

0.62 (3.63)

1.44 (6.85)

1.65 (5.98)

T5 T. harzianum (50 g vine-1

) + P. fluorescens (100 ml vine-1

) as soil application + P. fluorescens as spray (1%)

24.07 (29.37)

4.111 (11.69)

12.35 (20.56)

24.28 (29.51)

31.89 (34.36)

T6 Bordeaux mixture (1%) spray + copper oxychloride (2 g l-1

) drench 29.63 (32.96)

7.82 (16.22)

16.05 (23.60)

19.76 (26.37)

35.60 (36.62)

T7 Copper hydroxide (2 g l-1

) spray + drench 30.46 (33.48)

9.26 (17.70)

19.13 (25.92)

29.63 (32.96)

43.42 (41.20)

T8 Untreated control 34.36 (35.87)

15.64 (23.38)

27.78 (31.78)

52.47 (46.40)

62.76 (52.38)

Mean 29.76 (29.33)

5.17 (9.51)

11.50 (16.11)

19.90 (22.00)

27.14 (29.31)

S.Em. ± 0.368 1.323 0.763 0.476 1.244

CD @ 5 % 1.150 4.012 2.315 1.444 3.733

* Figures in parenthesis are arcsine transformed values

0

10

20

30

40

50

60

70

T1 T2 T3 T4 T5 T6 T7 T8

June July August September October

Fig. 5. Incidence of yellowing index (%) in integrated management of Phytophthora foot rot of black pepper

Fig. 5. Incidence of yellowing index (%) in integrated management of Phytophthora foot rot of black pepper

No defoliation was recorded in case of Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray and drench integrated with bioagent T. harzianum, P. fluorescens and plant product neem cake (T4), during July month. Maximum defoliation index was recorded with untreated black pepper vines. Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray and drench (7.12%) was on par with Potassium phosphonate integrated with T. harzianum, P. fluorescens and neem cake. The other treatments Bordeaux mixture spray followed by Copper oxychloride (T6) (11.92%), T. harzianum and P. fluorescens as soil application followed P. fluorescens as foliar spray (T5) (12.24%), Potassium phosphonate as spray and drench (T1) (13.10%) and Copper hydroxide (spray and drench) (T7) (14.60%) were on par with each other and significantly differ over control treatment.

Similar trend was observed in August month also. Again Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) with bioagents and plant product (T4) was recorded least defoliation index (1.50%) and highest was recorded with untreated vines (22.13%). The treatment Potassium phosphonate as spray and drench with bioagents and plant product (T2) (2.12%) was found on par with Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) alone as spray and drench (T3) (3.69%). Trichoderma harzianum, P. fluorescens as soil application with foliar spray of P. fluorescens (T5) (11.91%) was on par with Bordeaux mixture as spray followed by Copper oxychloride drench (T6) (13.37%).

During September, again Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) spray and drench integrated with bioagents T. harzianum, P. fluorescens and plant product neem cake (T4) was recorded minimum defoliation index (4.24%) which was followed by Potassium phosphonate as spray and drench along with application of bioagents and neem cake (T2) (9.31%). Defoliation index was higher in the untreated vines (T8) (37.47%). Defoliation index of Metalaxyl MZ 72 WP (Ridomil MZ 72 WP)(T3) (14.33%) was on par with that of Potassium phosphonate (T1) (16.65%) and Bordeaux mixture spray followed by copper oxychloride drench (T6) (21.94%) was on par with bioagents T. harzianum, P. fluorescens as soil application followed by foliar spray with P. fluorescens (T5) (23.11%).

During October, defoliation index was minimum (2.60%) in the treatment Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) application along with T. harzianum, P. fluorescens and neem cake (T4). It was followed by Potassium phosphonate combined with T. harzianum, P. fluorescens and neem cake (T2) and Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (T3). Maximum defoliation index was observed in untreated vines (T8) (Table 10).

4.7.4 Collar infection (%)

In the pre-monsoon season observation, as the vines affected with collar infection and wilting were not considered for treatments imposition, during June there was no significant difference among the treatments for collar infected and wilted vines.

During July, no collar infection of vines was observed in the treatments Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) and Potassium phosphonate as spray with drench along with bioagents T. harzianum, P. fluorescens and plant product neem cake. Highest collar infection was recorded in untreated black pepper vines (T8) (32.00%). Potassium phosphonate spray and drench (T1), Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray and drench (T3) and bioagents T. harzianum. P. fluorescens as soil application followed by P. fluorescens as spray (T5) were recorded equal amount collar infection percentage (13.59).

During August, least collar infection was observed with Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) spray and drench along with bioagents and plant product (T4) (13.57%). Maximum collar infection was recorded in untreated vines (T8) (44.98%). Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray and drench (19.45%) (T3) was found on par with Potassium phosphonate combined with T. harzianum, P. fluorescens and neem cake (T2) (19.45%). Bordeaux mixture as spray followed by drenching with Copper oxychloride (T6) (28.10%) was on par with Copper hydroxide as spray and drench (T7) (28.10%). The treatment Potassium phosphonate alone as spray and drench (T1) was recorded 24.08 per cent collar infection and bioagents alone T. harzianum, P. fluorescens as soil application followed by foliar spray with 1 per cent P. fluorescens was recorded 31.79 per cent collar infection.

Table 10. Incidence of defoliation index (%) in integrated management of foot rot of black pepper

Tr. no.

Treatment details June July August September October

T1 Potassium phosphonate (3 ml l-1

), spray + drench 30.66 (33.61)

5.15 (13.10)

1.44 (6.85)

8.23 (16.65)

14.61 (22.45)

T2 Potassium phosphonate (3 ml l-1

), spray + drench + Trichoderma harzianum (50 g vine

-1) + Pseudomonas fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

34.36 (35.87)

1.64 (7.33)

0.41 (2.12)

2.97 (9.31)

5.56 (13.57)

T3 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench 33.74 (35.50)

1.65 (7.12)

0.64 (3.69)

6.17 (14.33)

9.67 (18.10)

T4 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench + T. harzianum (50 g vine

-1) + P. fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

36.62 (37.23)

0.00 (0.00)

0.21 (1.50)

0.82 (4.24)

0.62 (2.60)

T5 T. harzianum (50 g vine-1

) + P. fluorescens (100 ml vine-1

) as soil application + P. fluorescens as spray (1%)

29.42 (32.84)

4.53 (12.24)

4.32 (11.91)

15.43 (23.11)

22.63 (28.37)

T6 Bordeaux mixture (1%) spray + copper oxychloride (2 g l-1

) drench 33.3. (34.62)

4.32 (11.92)

5.35 (13.37)

13.99 (21.94)

21.61 (27.67)

T7 Copper hydroxide (2 g l-1

) spray + drench 33.95 (35.62)

6.38 (14.60)

9.05 (17.50)

20.58 (26.96)

29.63 (32.96)

T8 Untreated control 34.57 (36.37)

12.4 (20.38)

14.20 (22.13)

37.04 (37.47)

52.67 (46.51)

Mean 31.76 (31.29)

4.48 (9.63)

4.45 (8.78)

12.78 (17.11)

18.63 (21.36)

S.Em. ± 0.368 0.717 1.123 0.962 1.202

CD @ 5 % 1.115 2.173 3.405 2.918 3.646

* Figures in parenthesis are arcsine transformed values

0

10

20

30

40

50

60

T1 T2 T3 T4 T5 T6 T7 T8

June July August September October

Fig. 6. Incidence of defoliation index (%) in integrated management of Phytophthora foot rot of black pepper

Fig. 6. Incidence of defoliation index (%) in integrated management of Phytophthora foot rot of black pepper

Table 11. Incidence of collar infection (%) in integrated management of foot rot of black pepper

Tr. no.

Treatment details June July August September October

T1 Potassium phosphonate (3 ml l-1

), spray + drench 0.00 (0.00)

5.56 (13.59)

16.67 (24.08)

22.22 (28.10)

27.78 (31.79)

T2 Potassium phosphonate (3 ml l-1

), spray + drench + Trichoderma harzianum (50 g vine

-1) + Pseudomonas fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

0.00 (0.00)

0.00 (0.00)

11.11 (19.45)

11.11 (19.41)

16.67 (24.08)

T3 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench 0.00 (0.00)

5.56 (13.59))

11.11 (19.45)

11.11 (19.41)

27.78 (31.78)

T4 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench + T. harzianum (50 g vine

-1) + P. fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

0.00 (0.00)

0.00 (0.00)

5.56 (13.57)

5.56 (13.53)

5.56 (13.53)

T5 T. harzianum (50 g vine-1

) + P. fluorescens (100 ml vine-1

) as soil application + P. fluorescens as spray (1%)

0.00 (0.00)

5.56 (13.59))

27.78 (31.79)

33.33 (35.23)

28.89 (32.49)

T6 Bordeaux mixture (1%) spray + copper oxychloride (2 g l-1

) drench 0.00 (0.00)

11.11 (19.45)

22.22 (28.10)

22.22 (28.10)

27.78 (31.78)

T7 Copper hydroxide (2 g l-1

) spray + drench 0.00 (0.00)

16.67 (24.08)

22.22 (28.10)

27.78 (31.79)

38.89 (38.56)

T8 Untreated control 0.00 (0.00)

28.11 (32.00)

50.00 (44.98)

72.22 (58.18)

77.77 (61.87)

Mean 0.00 (0.00)

9.07 (14.53)

20.83 (26.18)

25.69 (29.22)

31.39 (33.24)

S.Em. ± - 0.687 0.183 0.935 0.781

CD @ 5 % - 2.086 2.466 2.835 2.567

* Figures in parenthesis are arcsine transformed values

0

10

20

30

40

50

60

70

80

T1 T2 T3 T4 T5 T6 T7 T8

June July August September October

Fig. 7. Incidence of collar infection (%) in integrated management of Phytophthora foot rot of black pepper

During September, least collar infection (13.53%) of vines was observed in the treatment Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) combined with bioagents and neem cake (T4) and maximum collar infection (58.18%) in untreated vines (T8). Collar infection of Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) alone as spray and drench (T3) (19.41%) was on par with Potassium phosphonate along with bioagents and neem cake (T2).

During October, collar infection was minimum (13.53%) with Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray and drench integrated with T. harzianum, P. fluorescens and neem cake (T4) and maximum with untreated vines (T8) (61.87%). Collar infection was not significantly differ in the treatments Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray and drench (T3) (31.78%), Bordeaux mixture spray followed by Copper oxychloride drench (T6) (31.78%), Potassium phosphonate as spray with drench (T1) (31.79%) and soil application of T. harzianum and P. fluorescens followed by foliar spray with P. fluorescens (T5) (32.49%) (Table 11).

4.7.5 Wilting (%)

In the pre-monsoon season observation, as the vines affected with collar infection and wilting were not considered for treatments imposition, during June there was no significant difference among the treatments for collar infected and wilted vines.

During July month, only untreated black pepper vines were affected by wilting (19.44%).

During August month also, no wilting of vines was recorded in the treatments Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) integrated with bioagents and plant product (T4), Potassium phosphonate integrated with bioagents and plant product (T2) and Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) alone as spray and drench (T3). Maximum wilting of vines was recorded in untreated vines (T8) (24.03%) followed by Copper hydroxide as spray and drench (T7) (19.44%). Per cent wilted vines was found on par with the treatments Potassium phosphonate alone as spray and drench (T1) T. harzianum, P. fluorescens as soil application followed by foliar spray with P. fluorescens (T5) (13.57%) and Bordeaux mixture as spraying and drenching with Copper oxychloride (T6) (13.50%).

During September, least wilting of vines (0.00%) was observed in the treatment Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) combined with bioagents and neem cake (T4) and maximum wilting of vines (44.98%) in untreated vines (T8). Wilting of vines in Potassium phosphonate (T1) (19.4%) was on par with Copper hydroxide (T7) (19.75%) as spray and drench.

During October, least wilted vines were observed with the application of Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray with drench followed by T. harzianum, P. fluorescens and neem cake (T4) (0.00%). It was followed by combination of Potassium phosphonate as spray and drench with T. harzianum, P. fluorescens and neem cake (T2) (13.51%). Wilted vines percentage with Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (T3) (19.49%) was on par with foliar spray of Bordeaux mixture followed by Copper oxychloride drench (T6) (19.75%). Maximum wilted vines percentage was recorded in untreated vines (T8) (44.98%) (Table 12).

Table 12. Incidence of wilted vines (%) in integrated management of foot rot of black pepper

Tr. no.

Treatment details June July August September October

T1 Potassium phosphonate (3 ml l-1

), spray + drench 0.00 (0.00)

0.00 (0.00)

5.56 (13.57)

11.11 (19.41)

16.67 (24.07)

T2 Potassium phosphonate (3 ml l-1

), spray + drench + Trichoderma harzianum (50 g vine

-1) + Pseudomonas fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

0.00 (0.00)

0.00 (0.00)

0.00 (0.00)

0.00 (0.00)

5.56 (13.51)

T3 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench 0.00 (0.00)

0.00 (0.00)

0.00 (0.00)

5.56 (13.60)

11.11 (19.49)

T4 Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (1.25 g l-1

) as spray + drench + T. harzianum (50 g vine

-1) + P. fluorescens (100 ml vine

-1) as soil application +

neem cake (1 kg vine-1

)

0.00 (0.00)

0.00 (0.00)

0.00 (0.00)

0.00 (0.00)

0.00 (0.00)

T5 T. harzianum (50 g vine-1

) + P. fluorescens (100 ml vine-1

) as soil application + P. fluorescens as spray (1%)

0.00 (0.00)

0.00 (0.00)

5.56 (13.57)

16.67 (28.08)

22.22 (28.08)

T6 Bordeaux mixture (1%) spray + copper oxychloride (2 g l-1

) drench 0.00 (0.00)

0.00 (0.00)

5.56 (13.50)

11.11 (16.06)

11.11 (19.75)

T7 Copper hydroxide (2 g l-1

) spray + drench 0.00 (0.00)

0.00 (0.00)

11.11 (19.44)

22.22 (19.75)

27.78 (31.77)

T8 Untreated control 0.00 (0.00)

11.11 (19.44)

16.67 (24.03)

44.44 (44.98)

50.00 (44.98)

Mean 0.00 (0.00)

1.39 (2.43)

5.56 (10.51)

13.89 (22.70)

18.06 (22.70)

S.Em. ± - 0.197 0.823 0.978 0.978

CD @ 5 % - 0.600 2.496 2.966 2.966

* Figures in parenthesis are arcsine transformed values

0

5

10

15

20

25

30

35

40

45

50

T1 T2 T3 T4 T5 T6 T7 T8

June July August September October

Fig. 8. Incidence of wilted vines (%) in integrated management of Phytophthora foot rot of black pepper

Fig. 8. Incidence of wilted vines (%) in integrated management of Phytophthora foot rot of black pepper

Plate 8. Integrated management of Phytophthora foot rot of black pepper

5. DISCUSSION

Black pepper, the world’s most important spice, is one of the cash crops of Uttara Kannada. Black pepper originates from West tropical forests of Western Ghats in Kerala, India. It is generally being cultivated as mixed crop and foot rot disease is the major limiting factor in its production (De Waard, 1986). Several workers have formulated the management practices. However, the attempts made in the operation of single factor have met with little success.

Several workers reported in vitro screening of microorganisms for their antagonistic nature against Phytophthora capsici, but so far no reports are found on screening of native antagonists against P. capsici. Locally available green leaves extracts may contain toxic substances which inhibit the pathogen. Several workers recommended various systemic and contact fungicides to control this disease but so far, no chemical was found to be effective. Hence, there is an urgent need to search for new fungicide which can control this disease effectively.

An attempt has also been made to find out resistance source by screening cultivated cultivars of black pepper. As the disease affects all the parts of vine and is systemic in nature, any single method cannot control the disease effectively. Hence, an attempt was made with integration of chemicals, bioagents and plant product. The results obtained in the studies are discussed hereunder.

5.1 SURVEY FOR THE DISEASE INCIDENCE, ISOLATION OF Phytophthora capsici AND PROVING ITS PATHOGENCITY

5.1.1 Survey and distribution

Fixed plot survey was conducted during premonsoon, peak monsoon and post monsoon season of 2006 in three taluks of Uttara Kannada district. During pre-monsoon season, maximum leaf infection was observed in Siddapur; foliar yellowing was higher in Sirsi; defoliation, collar infection and wilted vines were higher in Mundigesara village of Sirsi taluk. Occurrence of disease was observed in all the villages surveyed. However, the severity of the disease varied from the village to other. This variation in the disease severity may be due to the factors like location of the garden, maintenance of garden including cultural practices followed, type of the cultivars used and level of inoculum present in the soil (Sastry, 1982).

During the peak monsoon season also, Mundigesara village of Sirsi taluk recorded higher leaf infection, foliar yellowing, defoliation, collar infection and wilted vines.

In the very similar manner during post monsoon season also, Mundigesara village of Sirsi taluk recorded higher leaf infection, foliar yellowing, defoliation, collar infection and wilted vine.

There was increase in the incidence of disease from premonsoon season to post monsoon season. Death of the vines was prevalent in all the seasons but it was higher during post monsoon season. It may be attributed to high rainfall during peak monsoon, higher humidity and low temperature which are favorable for well established growth and development of the pathogen and also to cultural practices which helps in spread of the pathogen. Death of the vines was most prevalent in Mundigesara village of Sirsi taluk, Kantur village of Siddapur taluk and Bairumbe village of Yellapur taluk, due to foot rot disease. Similar reports on death of vines in Wynad region of Kerala was reported as early as in 1902 (Menon, 1949). Samaraj and Jose (1966) recorded death of pepper vines upto 20 per cent in Cannanore district (Kerala). While, Nambiar and Sarma (1977) recorded upto 25 to 30 per cent loss in some gardens in Cannanore and Calicut districts. In Lampung, an outbreak of foot rot occurred during 1967-68 destroying 40-50 per cent of pepper crop (De Waard, 1979). Such reports on losses due to heavy incidence of pepper wilt have been reported from Uttara Kannada (Sastry, 1982), Shimoga (Dutta, 1984), Uttara Kannada, Shimoga and Chikkamagalore (Jahagirdar, 1998) districts of Karnataka state.

However, the present study brought out detailed account on incidence of foot rot for it adopted a new method of recording observation as the disease affected all the parts of vine.

In the present study, leaf infection (%), foliar yellowing (%), defoliation, collar infection and wilted vines (%) were recorded (Anonymous, 2004). The present study has helped to identify the major areas affected to foot rot disease in Uttara Kannada district which would pave way for formulation of preventive management strategies. This led to identifying areas where potential threat has been observed due to foot rot. Similar studies were reported by Balakrishnan et al. (1986) and Anandaraj et al. (1989) in systemic surveys conducted in Calicut and Cannanore districts.

5.1.2 Symptomatology

The first symptom of the disease was noticed during the month of July i.e. one month after the onset of monsoon. Initially, symptoms were noticed on leaves of runner shoot as dark brown spots with fimbriate margin. Later, the disease gradually spread to leaves including inflorescence. Gradually, infection spread to the collar region and root portion of the vines, which lead to yellowing, flaccidity and defoliation of leaves. Cracking at the nodal region formed characteristic symptoms of the disease. Sudden yellowing followed by wilting of vines is the typical symptoms during post monsoon period. Similar type of symptoms were recorded by several workers (Nambiar and Sarma, 1977; Sastry, 1982; Anandaraj et al., 1988, Subramanyam, 1993; Matsuda et al., 1996; Jahagirdar, 1998 and Lokesh, 2000).

5.1.3 Isolation and pathogenicity

Isolation of P. capsici from the infected black pepper tissues was made on oat meal agar media incorporated with pimaricin, vancomycin, pentachloronitrobenzene and hymaxazole (PVPH) (Tsao and Guy, 1977). The medium suppressed the growth of the Pythium and Fusarium spp. that usually contaminated the tissues. Phytophthora capsici was also isolated from soil collected around the root zone of wilted black pepper vines by castor seed baiting technique. Narasimhan and Ramakrishnan (1969), Sastry (1982), Subramanyam (1993) and Hegde (1993) also used this technique successfully to isolate P. capsici from foot rot sick soils.

5.2 ISOLATION OF NATIVE ANTAGONISTIC MICROORGANISMS AND THEIR IN VITRO EVALUATION AGAINST P. capsici

5.2.1 Isolation of native antagonistic microorganisms from soil

Native antagonistic microorganisms have rhizosphere competency with high antagonistic potential as studied by several workers. Various isolates of native antagonists belonging to fungal and bacterial groups showed antagonistic potential against P. capsici. Trichoderma viride, T. harzianum, T. koningii and Gliocladium virens isolated in black pepper plantation of Kerala and Karnataka were found predominant and antagonistic or parasitic to P. capsici (Anonymous, 1996).

5.2.2 In vitro evaluation of native antagonists against P. capsici

Biological control of plant diseases would help in preventing increase of pathogen population and also health hazards because of use of various synthetic chemicals. Biological control through the use of antagonistic microorganisms is a potential, non-chemical means of controlling plant diseases by reducing inoculum level of pathogen. The present investigation assessed the antagonistic effect of different native antagonists by dual culture technique.

Maximum reduction in radial growth of P. capsici was observed in Trichoderma sp. of Mundigesara isolate which was at par with Trichoderma sp. of Yellapur isolate and both were significantly superior to all other fungal and bacterial isolates tested. Next best isolate was Trichoderma sp. of Gudnapur isolate, it was on par with Edahalli and Siddapur isolates. Bacterial isolates recorded minimum inhibition of P. capsici. Trichoderma sp. showed more mycelial inhibition of the pathogen compared to bacterial antagonists. This could be obviously attributed to several possibilities of existence of microbial interactions such as higher competitive ability, stimulation, antibiosis by these Trichoderma native isolates over test pathogen. This has been reported by many workers (Porter, 1924; Gaffer, 1969 and Naik and Sen, 1995). The antagonism of Trichoderma spp. against many fungi is mainly due to production of acetaldehyde (Robinson and Park, 1966; Dennies and Webster, 1971). This

may also be the reason for antagonistic effect of native isolates of Trichoderma against P. capsici. Filippi et al. (1989) reported antagonistic nature of Bacillus subtilis and Pseudomonas sp.

Similar results wherein the efficacy of Trichoderma spp. and Pseudomonas sp. against the pathogen P. capsici was previously reported by Kaster (1938), Nambiar and Sharma (1977), Subramanyam (1993), Anandaraj et al. (1995), Anon. (1997), Jahagirdar (1998), Jubina and Girija (1998), Sodsa-art and Soytong (1999), Anith and Manomohandas (2001), Anith et al. (2002), Rajan et al. (2002) and Anith et al. (2003).

5.3 IN VITRO EVALUATION OF BOTANICALS AND FUNGICIDES AGAINST P. capsici

5.3.1 Effect of botanicals of P. capsici

Use of synthetic chemicals for management of plant diseases posed a lot of problems, whereas botanicals are locally available, relatively cost effective, easily accessible, non-phytotoxic, readily bio-degradable, systemic ephemeral and environmentally non-pollutive and hence, constitute a suitable plant protection strategy in biological management of plant disease. Hence, screening of plant products for its effective antifungal activity against the pathogen is essential requirement to minimize the use of fungicides and to consider as one of the components in the integrated disease management (Khadar, 1999 and Nagesh, 2000).

In the present investigation, except tikki weed (Tridax procumbens) at 5 per cent concentration, all the plant extracts tested at both 5 and 10 per cent concentrations were significantly effective in reducing the growth of Phytophthora capsici. Garlic clove extract (36.58%) at 10 per cent concentration proved to be most effective botanical. This was followed by duranta, eupatorium, neem and lantana at 10 per cent concentration, which were at par with each other. At 5 per cent concentration also, among all the botanicals tested, garlic clove extract (28.87%) proved to be the most effective botanical.

For the control of Pythiaceous fungi, solubility of the chemical in water is an added advantage since free water is required to complete life cycle of these organisms (Bruin and Edgington, 1988). Since the aqueous extracts of garlic cloves, leaves of duranta, eupatorium, neem and lantana were found to affect the radial growth of P. capsici, the water soluble nature of toxic principle in these plant extracts is ideal for developing into a botanical pesticide.

In the present investigation, contrary to the reports of Hegde (1983) and Subramanian (1993), neem (Azadirachta indica) also proved as one of the effective botanicals against P. capsici. The present investigation of various botanicals inhibiting the growth of P. capsici are in line with findings of Anandaraj and Leela (1996), Louis et al. (1996) and Leela et al. (2003).

In the present investigation, though complete inhibition of the pathogen was not recorded in any of the plant extract tested, but considerable amount of inhibition was noticed in some of them and then hold promise with their use for management of foot rot of black pepper.

5.3.2 Efficacy of fungicides against P. capsici

The present investigation revealed that cent per cent inhibition of mycelial growth of P. capsici was recorded with Akomin, Melody, Ridomil MZ 72 WP and Secure at 0.1, 0.2 and 0.3 per cent concentrations. Aliette and Bordeaux mixture also recorded cent per cent mycelial inhibition at 0.3 per cent concentration.

The present investigation identified the fungicidal nature and efficacy of two new chemicals Melody Duo and Secure which recorded cent per cent mycelial inhibition in vitro screening, at all the three concentrations.

Jahagirdar (1998) reported the fungicidal nature of Akomin, a plant tonic generally being recommended for plantation crops. The laboratory evaluation of Ridomil against Phytophthora parasitica var. nicotianae revealed significant reduction in growth and sporulation of fungus at 0.1, 0.2, 0.3 and 0.4 per cent concentration (Reddy and Nagarajan,

1980). Sastry (1982) reported Bordeaux mixture (1%), Blitox and Metalaxyl which were found effective in inhibiting the growth and sporangial formation of P. capsici and P. meadii.

Similar reports in in vitro screening were reported by Ramachandran and Sarma (1989), Ramachandran and Sarma (1990), Ramachandran et al. (1990b). The present investigation results are also in line with the findings of Nair and Sasikumaran (1991), Subramanyam (1993), Jahagirdar (1998) and Veena and Sarma (2000).

5.4 SCREENING OF BLACK PEPPER VARIETIES AGAINST Phytophthora capsici

Use of host resistance is one of the best methods of controlling soil borne pathogens. Several workers have screened the cultivated and wild types of black pepper for resistance (Muller, 1936; Holliday and Mowat, 1963; Ruppel and Almeyda, 1965; Albuquerque, 1968; Alconero et al., 1972; Turner, 1973; Sitekpu and Prayitno, 1979; Mohd and Hussin, 1986; Ramachandran et al., 1988; Sarma et al., 2000 and Veena et al., 2003).

In the present investigation, all the nine varieties were found susceptible when screened in wilt sick-soil. However, time taken for first appearance of symptoms and wilting were different for different variety indicating that there is difference in resistance among them. P-24 and HP-34 took longer period for wilting. Similarly, P-24 showed a tolerant reaction in an earlier study (Anonymous, 2003).

5.5 INTEGRATED MANAGEMENT OF PHYTOPHTHORA FOOT ROT OF BLACK PEPPER

In the present investigation on field trial on integrated management of foot rot of black pepper, various treatments or their interactions showed a positive influence on significant reduction in disease intensity on treated vines. As mentioned earlier, in the present investigation for the first time, though the observations on leaf infection, foliar yellowing and defoliation were recorded, collar infection and wilting of the vines were found as crucial stages which obviously led to death of vines.

In all the five months of observations, with some variation in leaf infection, yellowing index and defoliation index, the treatment Ridomil MZ 72 WP integrated with bioagents Trichoderma harzianum, P. fluorescens and a plant product neem cake performed better in reduction of intensity of leaf infection, yellowing, defoliation, collar infection and wilt incidence. It was followed by application Potassium phosphonate as spray and drench along with T. harzianum, P. fluorescens and neem cake. This was followed by Ridomil MZ 72 WP alone and Potassium phosphonate alone. The application of these best treatments twice, once in the month of May-June and in August-September helped in checking the spread of the disease may be due to reduction in inoculum level.

During this field trial, though in the initial periods of observation, bio-agents alone and fungicides alone also performed better in bringing down the disease incidence. However, after 60 days the vines which received the treatment combination of systemic fungicide and bioagents along with plant product neem cake, i.e. Ridomil MZ 72 WP and Potassium phosphonate as spray and drench followed by bioagents T. harzianum, P. fluorescens and neem cake performed better throughout the rest of the period and significantly brought down the incidence. This may be due to synergistic effect of treatment combination on reduced disease incidence.

The present integrated management proved that the components of IDM as eco-friendly, economically feasible and compatible. Curl (1976) opined that combined application of PCNB with T. harzianum effectively controlled Rhizoctonia solani in cotton seedlings than T. harzianum alone in greenhouse studies. Similar report of integration of biological agent and chemicals was reported by Henis et al. (1978). Subramanyam (1993) observed that integrated application of Metalaxyl + neem cake + Trichoderma thrice is effective against Phytophthora capsici wilt of black pepper. The application of neem cake + phorate + Bordeaux mixture + Akomin was found effective in Phytophthora disease of pepper (Anon., 1996). The combined application of Trichoderma viride + Akomin brought down incidence of black pepper wilt (Anon., 1996).

The present study on the results of integration of systemic chemicals and bio-agents were also found similar to the findings of Hegde and Anahosur (1998), Jahagirdar et al. (2000) and Srinivasan, et al. (2003).

The present investigation showed that application of best treatment twice at proper time would not help in bringing down the incidence thus, reducing the applications of the treatments in the management of the disease.

Despite many achievements in modern agriculture, chemical management still holds a strong promise in combating certain destructive diseases. Thus, the present study apart from integrated treatments, identified application of Ridomil MZ 72 WP (0.2%) or Potassium phosphonate (0.2%) as spray and drench to effectively reduce the disease intensity. The effects of systemic fungicides on reduced incidence of disease has been also reported by Dastur (1927), Uppal (1931) Subramanian and Venkat Rao (1970), Narasimhan et al. (1976) and Coffey and Bower (1984a). The systemic fungicides Metalaxyl and Fosetyl Al were found effective in the management of pepper wilt in field conditions (Sastry, 1982; Ramachandran and Sarma, 1985a; Anon., 1986). Newer fungicides reducing incidence with minimum defoliation were reported by Anonymous (1997), also.

Thus, the present investigation identified application of Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (0.125%) as spray and drench + soil application of T. harzianum (50 g vine

-1) and

P. fluorescens (100 ml vine-1

) + neem cake (1 kg vine-1

) as best treatment followed by potassium phosphonate (0.3%) + soil application of T. harzianum and P. fluorescens + neem cake, Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (0.125%) alone (spray + drench) and potassium phosphonate (0.3%) alone as spray followed by soil drenching, as the best treatments which can be adopted easily.

FUTURE LINE OF WORK

� Native antagonistic microorganisms were shown their efficiency in inhibiting the P. capsici under in vitro condition. These effective isolates of antagonists need to identify and further study in field condition

� Eupatorium is an abnoxious weed, predominantly growing in pepper growing areas. It was also found effective in vitro evaluation and is need to be study its efficiency in field condition

� As the many of earlier chemicals inefficient in preventing the collar infection and wilting of vines, newer fungicides should be evaluated. In in vitro evaluation two new fungicides Melody duo and Secure were found effective. Hence, these fungicides need to study their effectiveness in reducing collar infection and wilting of vines.

� More number of varieties of black pepper are need to be screened under field condition and also bio-chemical compounds responsible for resistance in such varieties need to be studied.

6. SUMMARY AND CONCLUSIONS

Black pepper is one of the most important spice crops. It is being called as King of spices. It is a traditional, historic spice crop which has been under cultivation since ancient times India. In India, black pepper is being cultivated in 2.2 lakh ha with 70,000 tonnes of production during 2005-06 and exported 28,750 tonnes of black pepper amounted to Rs. 306.2 crores. The production of black pepper is limited by many diseases. Among them foot rot caused by Phytophthora capsici is the most important and serious one. The disease causes infection on all the parts of vine and causes death of entire vine. In view of the destructive nature of foot rot of black pepper, the present investigation was planned with following objectives. Survey for disease incidence; isolation and proving pathogenicity of P. capsici. Isolation of native antagonistic microorganisms from soil and their in vitro evaluation against P. capsici. In vitro evaluation of botanicals and fungicides against P. capsici; Screening of black pepper varieties against P. capsici and integrated management of foot rot of black pepper.

• Pathogen of foot rot of black pepper was characterized as Phytophthora capsici on basis of morphological studies. Further, the fungus was confirmed as P. capsici by establishing its pathogenicity on cuttings.

• The survey report revealed a highest severity of the disease was in Mundigesara village of Sirsi taluk which was identified as hot spot of the foot rot of black pepper.

• Rhizosphere soil of healthy black pepper vines recorded the isolates of fungal (Trichoderma sp.) and bacterial (Pseudomonas sp. and Bacillus sp.) antagonists.

• Among the test antagonists, Trichoderma sp., a native isolate from Mundigesara, Yellapur and Edahalli isolates were most effective in inhibiting the growth of P. capsici. Least inhibition was noticed in Pseudomonas sp. of Yellapur isolate followed by Bacillus sp. of Siddapur.

• Among the ten plant extracts tested, garlic cloves extract was highly inhibitory to P. capsici and was followed by leaf extracts of duranta, eupatorium, neem and lantana. The least effective was tikki weed followed by adusoge.

• Out of ten fungicides tested in vitro, Akomin, Melody duo, Ridomil and Secure at all three concentrations (0.1%, 0.2% and 0.3%), Aliette and Bordeaux mixture at 0.3 per cent concentration were also highly inhibitory to the pathogen P. capsici. The least effective was Varita followed Copper oxychloride.

• Among the nine varieties screened in foot rot sick soil, though there was difference in mortality of seedlings, all the varieties found susceptible to P. capsici.

• In field, under integrated management trial, Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) (0.125%) as spray and drench in combination with T. harzianum and P. fluorescens along with neem cake application was most effective followed by Potassium phosphonate (0.3%) application along with T. harzianum, P. fluorescens and neem cake soil application. The least effective was copper hydroxide (0.2%) alone as spray and drench followed soil application of T. harzianum and P. fluorescens and foliar spray of P. fluorescens.

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* Originals not seen

STUDIES ON FOOT ROT OF BLACK PEPPER CAUSED

BY Phytophthora capsici Leonian, emend, Alizedeh

and Tsao. SHASHIDHARA S. 2007 Dr. M. S. LOKESH

MAJOR ADVISOR

ABSTRACT

Black pepper is one of the most important spice crops, belongs to the family Piperaceae. It is known as king of spices. In India, black pepper is being cultivated in 2.2 lakh ha with a production of 70,000 tonnes during 2005-06 and exported 28,750 tonnes worth of Rs.206.2 crores. The cultivation and production of black pepper is limited by many diseases of which foot rot caused by Phytophthora capsici is the most important and serious disease. The symptoms were noticed on all parts of vine and in advanced stage leads to death of the entire vine.

The survey report revealed a highest severity of the disease was in Mundigesara village of Sirsi taluk which was identified as hot spot for the disease. The pathogen Phytophthora capsici was isolated from the infected vines and characterized on the basis of morphological studies. The fungus was confirmed as P. capsici by proving pathogenicity on pepper.

In vitro evaluation of antagonists revealed that Trichoderma sp. of Mundigesara, Yellapur and Edahalli isolates were found to be effective in inhibiting the growth of P. capsici. Among the plant extracts tested, garlic clove extract followed by Duranta plumeri Jacq., Chromolaena odorata King., Azadiracta indica A. Juss. and Lantana camera L. leaf extracts. The Tridax procumbens Linn. is found to be least effective followed by Adathoda vesica Nees. against test pathogen. In vitro evaluation of fungicides viz., Akomin, Melody duo, Ridomil and Secure at 0.1%, 0.2% and 0.3% concentrations were found highly inhibitory to Phytophthora capsici.

Integrated management of the disease in field condition revealed that Metalaxyl MZ 72 WP (Ridomil MZ 72 WP) as spray and drench at 0.125% in combination with T. harzianum, P. fluorescens along with neem cake application was found to be most effective in reducing the disease incidence.