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Review of Literature
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REVIEW OF LITERATURE
Phytonematodes are an extremely important limiting factor in vegetable
production, therefore crop protection is an integral part of food production and must
be considered within the context of modern agriculture and sustainable development.
Effective crop protection is essential both to combat the threat of widespread diseases
and to provide the effective pest management programmes. The majority of the plant
species, which account for the major world’s food supply, is susceptible to attack
from phytonematodes which are capable of causing sustainable economic losses in the
quantity and quality of the crops (Jain et al., 2007; Berry et al., 2008). The crop losses
caused by phytonematodes in economic terms estimated about $ 157 billion annually
to the world agriculture (Abad et al., 2008). Yield losses due to root-knot nematodes
(Meloidogyne spp.) range from 35.0 to 39.7% (Reddy, 1985; Jonathan et al., 2001). In
India the losses of agriculture by phytonematodes estimated at about Rs. 210 crore
annually (Jain et al., 2007).
Phytonematodes are severely destroying the roots and other parts of various
crops. Roots damaged by the phytonematodes are not efficient in the utilization of
available moisture and nutrients from the soil resulting in reduced functional
metabolism. Visible symptoms of nematode attack often include reduced growth of
individual plants. Furthermore, damaged and weakened roots by nematodes are easy
prey to many types of fungi and bacteria, which invade the roots and accelerate root
decay. These deleterious effects on plant growth result in reduced yields and poor
quality of crops. To overcome this effect, management of nematode is, therefore,
important for higher yield and quality that are expected from the higher cost of crop
production (Vadhera and Shukla, 2002; Kumar and Ja in , 2007).
Once nematodes are established in the field, the possibilities of complete eradication
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are exceeding remote and impractical on field scale due to soil inhabitant nature of
nematodes. However, several measures are adopted to decrease nematode population
up to an acceptable level. The main objectives of phytonematodes management are
usually a matter of reducing the nematode population by one or more methods or
integration of one or more methods to a low level so that the damage is negligible or
at an economically acceptable level (Rajvasnshi and Sharma, 2007).
Integrated Nematode Management (INM) evolved as a philosophy and
technique for the alleviation of real, potential or perceived problems associated with
nematode management programmes (Allen and Bath, 1980; Akhtar, 1997; Sikora et
al., 2005). The integrated nematode management strategy uses a combination of
different disease control methods to decrease disease, increase yield, minimize
environmental damage, prevent the buildup of resistant pathogen strains and produce
high quality products (Widmer et al., 2002).
Efficient management of plant parasitic nematodes requires the carefully
integrated combination of several methods. Although each individual method of
management has a limited use, together, they help in reducing the nematode
populations in agricultural soils or in plants. Integrated pest management (IPM)
provides a working methodology for pest management in sustainable agricultural
systems (Oka, 2010). One of the main objectives behind this work was to observe the
application of current methods for the management of plant-parasitic nematodes
within the guidelines of IPM. Integrated nematode management can broadly be
divided in cultural, chemical, biological, physical, host resistant and integrated crop
protection system, in which the best combination of resistant cultivars, crop rotation,
organic amendment and soil solarization can be utilized with minimum use of
nematicides.
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2.1. CULTURAL CONTROL
Control of nematodes by cultural practices is more economical or practical
especially on vegetable crops. Numerous cultural practices can be beneficial by
reducing population densities of plant-parasitic nematodes. These practices include
fallowing, cover crops, trap crops, antagonistic plants, weed management, flooding,
conservation tillage, green manuring, cropping systems etc. This operation is feasible
and can be adopted and carried out without extra expenses. Secondly the product can
be consumed at any time after harvest, as there are no residual effects of the chemical.
2.1.1. Crop rotation
Seasonal rotations of susceptible crops with non-host or poor-host crops in the
same area of land remain one of the most important techniques used for nematode
management worldwide (Viaene et al., 2006). By this method, the populations of
phytonematodes are reduced to a minimum level. This process should be repeated for
several years depending upon the initial population and decease rate of population.
The rotation must also provide economically useful crops. Choosing rotation, care
should be taken to avoid a new set of pathogens in place of the one to be controlled. A
number of crops and other plants have been found resistant to phytonematodes
(Stefanova and Fernandez, 1995; Gomez and Rodriguez, 2005; Rehman et al., 2006).
Use of Witchgrass in a peanut rotation has beneficial effects on soil, reducing
parasitic nematode populations (Kokalis-Burelle et al., 2002).
Similarly, rotation crops, such as beans, bahiagrass, maize and cabbage that
support extensive growth of the nematophagous fungus, Pochonia chlamydosporia in
their rhizosphere but support only limited reproduction of root-knot nematodes, are
used to maintain the abundance of the fungus in the soil whilst suppressing
populations of the nematode (Timper et al., 2001; Puertas and Hidalgo-Diaz, 2007).
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Hence, growing an approved crop in the rotation to maintain populations of natural
enemies on roots is another alternative to improve the efficacy of nematode
management programmes based on crop rotations (Rodríguez-kábana and Canullo,
1992).
The crop rotation may provide a short-term suppression of nematode
population densities (Starr et al., 2002). However, due to the polyphagous nature of
the pest as well as the relatively low economic value of some recommended rotational
crops, control of root-knot nematodes by crop rotation becomes very limited (Waceke
et al., 2001). It has been reported by several workers that different cropping sequences
reduce the populations of some harmful phytonematodes to the levels that do not
cause economic losses (Alam et al., 1981; Idowu and Fawole, 1989; Singh et al.,
1997; Haider et al., 2001; Haider and Pathak, 2001).
The crop rotation to a non-host crop is often adequate by itself to prevent
nematode population from reaching economically damaging levels. However, it is
necessary to positively identify the species of plant-parasitic nematodes in order to
select appropriate crops, which should be poor hosts or non-hosts for the prevailing
nematode species. The population of phytonematodes suppression by crop rotation
has been reported by many workers (Kluepfel et al., 1993) and it can also be induced
by crop rotation with antagonistic plants such as velvet bean (Mucuna deeringiana)
(Vargas et al., 1994) and switchgrass (Panicum virgatum) (Kokalis-Burelle et al.,
1995). Various cover or trap crops and antagonistic plants are useful for reducing
nematode populations as well as conserving soil and often improving soil texture
(Nusbaum and Ferris, 1973; Alam and Jairajpuri, 1990; Abawi and Thurston, 1994).
Haider et al. (2004) reported that the intercropping two rows of yellow sarson
(Brassica campestris var. sarson) with sugarcane were very effective to control the
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nematode disease. Similar results of inclusion of mustard, a poor host for several
nematodes, in different cropping sequences for reducing nematode populations have
been reported by several other workers (Singh and Sitaramaiah, 1993; Kumar et al.,
2006).
Some of the selected non-host plants that can be effectively used in the crop rotation
practice against various plant-parasitic nematodes are listed below.
List of some non/poor hosts that can be included in crop rotation (Minimum of two
year rotation)
Target nematode Non/ poor host
Globodera Wheat, strawberry, cabbage, cauliflower, peas,
maize, beans
Heterodera avenae Pea, maize, carrot, fenugreek, gram, mustard
Meloidogyne, Pratylenchus,
Tylenchorhynchus,Rotylenchulus,
Radopholus, Heterodera
Crotalaria spectabilis, C. striata. Tagetes spp.
Heterodera glycines Maize, cowpea, potato, tobacco, most vegetables
H. schachtii Alfalfa, bean, clover, maize, onion
H. zeae Wide range of crops
Globodera rostochiensis Maize, green beans, red clover
Hoplolaimus indicus Cabbage, chilli, eggplant
Meloidogyne javanica Cotton, groundnut, sorghum, velvet bean
M. hapla Maize, cotton, grasses, lettuce, onion, radish
M. incognita Fescue, orchard grass
Meloidogyne spp. Crotalaria spectabilis, millet, oats, wheat
Paratrichodorus minor Maize, Crotalaria spectabilis
Pratylenchus leiocephalus Groundnut
P. penetrans Alfalfa, beet, fescue, marigold, oats, rye
Pratylenchus spp. Lettuce, onion, radish
Radopholus similis Crotalaria spectabilis
Tylenchorhynchus mirzai Wheat
T. brassicae Potato, tomato
Xiphinema americanum Alfalfa, maize, fescue, tobacco
Source: Trivedi and Barker (1986)
Prasad et al. (2004) found the highest linseed equivalent when linseed was
intercropped with mustard followed by gram. The decrease in nematode populations
by intercropping mustard could be attributed to the presence of 2-propenyl
isothiocynate in mustard having nematicidal activity as reported by Kowalska and
Sonalinska (2001).
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Recently, Sundararaju (2005) reported that the maximum reduction in root-
lesion index and nematode population was observed where marigold (Tagetes erecta)
was grown as an intercrop and was at par with chemical treatment. Similar findings
were also reported by several workers who reported that intercropping marigold with
different crops can reduce the population of plant-parasitic nematodes thereby
exhibiting a better plant growth (Yen et al., 1998; Dhanger et al., 2002; Uma Shankar
et al., 2005).
Some of the cover/trap crops, which can be used for managing plant-parasitic
nematodes, are listed below.
Nematode species Trap crop Reference
Meloidogyne spp.
Crotalaria spectabilis,
Cowpea, English pea,
Periwinkle, Tagetes
minuta, Ricinus communis
Christie, 1959; Godfrey and
Hagan, 1934; Patel et al., 1991;
Owino and Waudo, 1995.
Heterodera avenae Oat Stone, 1961
H. schachtii Hesperis matronalis Moriarty, 1961
Globodera spp. Potato Carroll and McMahon, 1939
Vetrivelkalai and Subramanian (2006) observed that the population dynamics
of several plant-parasitic nematode species reduced sharply during the fallow period
in all the cropping sequences viz., sorghum-fallow, tomato-fallow, cotton-fallow and
black gram-fallow. The least population of M. incognita was observed during the
cropping period but not recovered during the fallow period in tomato-fallow and
cotton-fallow cropping sequences. Similar results were also reported by Wani (2005)
who observed that the cropping-sequence wheat-chilli-fallow caused the greatest
reduction in the nematode population followed in the descending order of efficiency
by chickpea-okra-chilli, mustard-mung-tomato and tomato-fallow-okra, however, the
extent of field ploughing also playing an important role and deep ploughing being
more effective than normal ploughing. Similarly, Cabanillas et al. (1999) reported that
sorghum-fallow and cotton-fallow reduced R. reniformis populations.
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2.1.2. Biofumigation
The term biofumigation is used when volatile substances are produced through
microbial degradation of organic amendments that result in significant toxic activity
towards nematodes or diseases (Bello et al., 1997). Generally, biofumigation is more
effective when there is an optimum combination of organic matter, high soil
temperature and adequate moisture to promote microbial activity. In Spain,
biofumigation has been largely applied successfully as an alternative to methyl
bromide in several crops (Bello et al., 2001).
Soil amended with fresh or dry cruciferous residues reduce significantly root-
knot nematode infestations, principally, due to isothiocyanates released in soil when
glucosinolates present in these crop residues are hydrolyzed (Stapleton and Duncan,
1998; Diaz-Viruliche, 2000; Ploeg and Stapleton, 2001; D’Addabbo et al., 2005).
However, the practical application of this approach is limited due to the large amount
of organic matter to be transported to the field or the cost of cover crops to be
incorporated into the soil, together with the plastic mulch and drip irrigation system
often necessary to improve the effectiveness of biofumigation. Also, the provision of
large amounts of nutrients to soils may affect the activity of facultative parasites of
nematodes. Among non-chemical alternatives, biofumigation, based on the use of
gasses resulting from the decomposition of organic matter, has demonstrated great
efficacy as an alternative to the use of methyl bromide, whose ban is imminent due to
its environmental impact (Bello et al ., 2003).
2.1.3. Tillage practices and Fertilizer application
Tillage practices play an important role in integrated nematode management
approaches, integration of tillage practices with other nematode management practices
viz., organic amendment, nematicides and crop rotation, soil solarization are very
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effective to the control of phytonematodes. Consistent effects of tillage practices on
nematode population densities have been reported by many workers (Minton, 1986;
McSorley and Gallaher, 1993) and greater effect was obtained from deeper ploughing
(Siddiqui, 2005, 2007; Ahmad et al., 2007b). Although tillage practices may be of
some benefit in nematode management, much more success has been achieved
through the design of effective cropping systems (McSorley and Gallaher, 1994).
Roget et al. (1987) have shown that the number of cysts of Heterodera avenae on
roots and the amount of damage caused by the nematode on wheat are reduced by
conservation tillage. Depth of ploughing influences the populations of plant-parasitic
nematodes; a greater reduction in nematode numbers was observed in deep-ploughed
than in normally ploughed agricultural soils (Tiyagi and Alam, 1995). Nematode
densities have shown to be greater in deep ploughed compared with normal ploughed
plots (Fortnum and Karlen, 1985; Jain and Bhatti, 1985; Mathur et al., 1991; Akhtar,
1997; Siddiqui, 2003, 2007; Anver, 2006). Siddiqui and Alam (1991) reported that the
depth of ploughing had a great influence on the population of plant parasitic
nematodes. The deep ploughing brought about a significant reduction in the
population of plant parasitic nematodes over normal ploughing treatment. The
combined effect of organic amendment/nematicides and ploughing reduced the
population level of phytonematodes (Siddiqui, 2007). The suppressive effect of deep
ploughing has been reported by several workers (Siddiqui and Alam, 1991; Anver,
2006).
It has been suggested that the deep ploughing disturbs the ecological set up of
nematodes which are exposed to external unfavorable conditions and thus their
population decline (Siddiqui and Alam, 1999). Siddiqui and Alam (2003) reported
that the integrated effect of ploughing, nematicides and organic amendment on the
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population of phytonematodes were very effective and it reduced to an acceptable
level. The population of Meloidogyne spp. decreased drastically when the field was
puddled every year over a 10 year period (Pankaj et al., 2006). Siddiqui and Alam
(1999) reported that the integrated effect of oil cakes, nematicides and ploughing were
very effective in reducing the population of phytonematodes and promoted the plant
growth characters.
Badra (1980) stated that ammonical nitrogen maintained in an amount up to
576 kg/ha at two intervals decreased damage caused by R. reniformis to tomato.
Additional experiments with urea, which is readily converted to ammonia by urease
present in the soil, showed that it is also a good nematicide if applied at levels in
excess of 300 mg/kg soil (Rodriguez-Kabana and King, 1980; Huebner et al., 1983).
Ismail et al. (2006) also reported that the soil and root population of R. reniformis
which reduced steadily with increasing the doses of nitrogen incorporated organic
amendments. Slight increase in infestation and invasion of R. reniformis was
associated with lower doses of potash. Incorporation of nitrogen and phosphorus was
promising for plant growth as well.
2.2. ORGANIC SOIL AMENDMENTS
Organic soil amendments can be successfully employed for the control of
plant parasitic nematodes. A variety of organic amendments, such as animal and green
manures, compost, nematicidal plants and proteinous wastes are used for the control
of phytonematodes (Oka, 2010). Application of organic amendments into the soil is
not only beneficial to nematode management but also improving the plant growth and
productivity (Adegbite and Adesiyan, 2005). On the other hand, application of
organic substrates leads to build up of beneficial micro flora around the rhizosphere,
which will help to reduce the plant parasitic nematodes in the soil (Oka, et al., 2007).
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2.2.1. Antagonistic crops and Composts
Plants antagonistic to nematodes are those that are considered to produce
toxic substances, usually, while the crops are growing or after incorporation into the
soil. In nematode management strategies the use of this approach relies on preplant
cover crops, intercropping or green manures. Marigold, neem, sunnhemp, castor bean,
partridge pea, asparagus, rape seed, crotalaria and sesame have been extensively
studied and used as antagonistic crops for nematode control (Wang et al., 2002,
2003).
Germani and Plenchette (2004) recommended the use of Crotalaria spp. as
precrops for providing green manure while at the same time decreasing the level of
root knot nematode and increasing the level of beneficial mycorrhizal fungi.
Incorporation of plant residues generally increases the number of free-living
nematodes, but increases in specific nematode genera may be affected by plant
residue type (McSorley and Frederick, 1999), which in turn may affect antagonistic
organisms, such as predatory nematodes and parasitic fungi. Incorporation of
sunnhemp (Crotalaria juncea) to soil increased nematode-trapping fungi, parasitic
fungi on R. reniformis eggs, vermiform stage parasites and bacterivorous nematodes
more efficiently than amendments with Brassica napus or Tagetes erecta (Wang et
al., 2001; Wachira et al., 2009). The population of R. reniformis was highly reduced
in growing mustard, wheat, fennel, carrot, sorghum, sesbania (Siddiqui and Alam,
2001)
Chrysanthemum coronarium significantly reduced root-knot nematode
infection of tomato roots and improved plant fresh weight (Bar-Eyal et al., 2006). The
use of soil amendments with organic matter to control nematode populations has been
reported by several researchers (Ferraz and Freitas, 2004; Halbrendt and Lamondia,
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2004). Similarly, the results of soil amendment with neem, Jatropha and castor leaves
are very effective (Kalaiarasan et al., 2007; Lopes et al., 2011).
Ritzinger and McSorley (1998) amended the soil with different quantities of
dry castor leaves and concluded that application at the rate of 0.5% was sufficient to
significantly reduce the population of M. arenaria Neal (Chitwood). The nematicidal
properties of castor plant have been attributed to ricin, a substance found only in the
seeds. Some of the plant parts such as roots, shoots, leaves, flowers and crop residue
are left intentionally in the field after harvest and ploughed deep into the soil, these
organic additives after their proper decomposition by the activity of several
microorganisms resulted in the suppression of many plant pathogens like plant-
parasitic nematodes (Johnson, 1971, 1972; Siddiqui and Alam, 1995, 1997, 1999).
The incorporation of mature dried residues of lespedeza, alfalfa, oats and flax into the
soil infested with M. incognita, significantly reduced the incidence of the nematode
on tomato (Johnson et al., 1967).
Cassava peelings, cocoa pod husk and rice husk significantly reduced
Meloidogyne spp. population infecting cowpea (Egunjobi, 1985; Egunjobi and
Olaitan, 1986). Cassava leaf and tuber rind applied as soil amendment @100g or 50
g/pot, significantly reduced the population of M. incognita and improved plant growth
parameters of okra (Ramakrishnan et al., 1999). Akhtar and Alam (1993) recorded
that vegetables, fruit processing waste and tobacco waste were most effective in
reducing the incidence of root-knot and the population of phytonematodes on tomato.
Soil amending with spent tea, wheat straw, paddy husk, sugar cane and domestic
garbage were beneficial in controlling the nematodes.
Some researchers reported that poultry refuse and mustard oil-cake were
effective in controlling root knot nematode and enhancing plant growth and yield of
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tomato (Faruk et al., 2001, 2002) and many other crops (Bari et al., 2004a, 2004b).
The accelerated yield of tomato under field conditions has been reported by other
investigators using higher doses of organic soil amendments alone or their application
at lower dose mixed with Furadan 5G (Faruk et al., 2001, 2002). Soil amendment
with poultry refuse has also been reported to be effective against root-knot nematode
of okra (Bari et al., 1999), brinjal (Bari et al., 2004a). Organic amendments like
sawdust of neem and mango greatly reduced root-knot development and
multiplication of R. reniformis on tomato and eggplant and Tylenchorhynchus
brassicae on cabbage and cauliflower. The nematode control gradually increased with
increasing the dose of sawdust. Sawdust of neem was more efficacious than that of
mango. The combined effect of sawdust and ammonium sulphate was greater than
either of the separate both with respect to nematode control and to the improvement in
plant growth (Siddiqui and Alam, 1990).
The phytotoxicity of sawdust was effectively eliminated by supplementing the
sawdust with ammonium sulphate (Siddiqui and Alam, 1990). The soil amending with
different parts of neem/margosa (Azadirachta indica A. Juss.) is reported to be highly
effective in reducing the population of different plant-parasitic nematodes affecting a
variety of plant species (Hellap and Dreyer, 1995; Rao et al., 1996; Zaki, 1998;
Umamaheshwari and Sundarababu, 2001; Siddiqui and Alam, 2001; Oka and Pivonia,
2002; Yasmin et al., 2003; Shah et al., 2004; Raman and Venkateshwarlu, 2006;
Siddiqui, 2006a; Rather and Siddiqui, 2007a, b, c).
Although possessing a limited scope to be used as manure, the sawdust has
been suggested for the pest management and control of plant-parasitic nematodes. A
significant reduction in the intensity of root galling was reported (Srivastava et al.,
1971) when sawdust applied in a field planted with okra, eggplant and tomato.
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However, various other workers have pointed out the reduction in nematode intensity
by amending the soil with sawdust (Bora and Phukan, 1983; Singh et al., 1986;
Osunlaja, 1990; Akhtar, 1998). Consequently, it becomes more advisable to employ
sawdust in combination with other materials such as different oil cakes, sugarcane
bagasse, nematicides, urea, cow dung and other biocontrol agents, as a nematode
suppressant (Kushwaha et al., 1983; Acharya and Padhi, 1988; Akhtar and Alam,
1993).
Soil organic matter helps to retain nutrients, maintain soil structure and hold
water for plant use. The addition of various rice straw composts on the rhizosphere
soil microorganisms showed a high fertilizer value when applied @ of 5% (w/w).
Various rice straw composts @ 5, 7.5 resulted in reducing root-knot nematode
population of 79, 84% respectively and actualized prodigious depletion in egg
production (Rashad et al., 2011). Organic amendment viz., rice husk, saw dust, cow
urine, cow dung and neem cakes have been significantly effective against M.
incognita (Shurtleff and Averre, 2000; Singh and Khurma, 2007; Nagraju et al.,
2010).
Animal manures have been used since the beginning of agricultural food
production to improve soil fertility, recycle nutrients, improve biological and physical
properties of soil and increase crop yield (Rodriguez-Kabana et al., 1987; Sims and
Wolf, 1994). The research with animal manures amended in the soil, have shown that
they possess nematode-suppressive properties (Montasser, 1991; Kalpan and Noe,
1993; Opperman et al., 1993; Stephan, 1995; Oka and Yermiyahu, 2002). The mode
of action, however, has not yet been fully determined. The application of manure
enhances soil fertility, aids in controlling plant-parasitic nematodes and provides a
mean of disposing of the manure.
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Many previous reviews have focused on the use of organic amendments to
control plant-parasitic nematodes (Rodríguez-Kábana, 1986; D’Addabbo, 1995;
Akhtar and Malik, 2000; Oka, 2010; Thoden et al., 2011). Farm manure trials have
frequently involved poultry or cattle litter. Poultry litter appeared to be an appropriate
choice (Gamliel and Stapleton, 1993a), especially when combined with a sorghum
cover crop (Everts et al., 2006). Abubakar et al. (2004) reported that soil amending
with cow dung, urine and their mixture significantly reduced the extent of root-galling
and nematode multiplication of root-knot nematode, M. incognita and improved the
various plant growth parameters of tomato. Similar results of reduction in nematode
populations by soil amending with cow dung were also reported by Babatola (1990)
and Abubakar and Majeed (2000).
Chicken litter, a common form of poultry manure, consists of manure and pine
shaving beddings, contains significant quantities of N, P, K, Ca, Mg and
micronutrients and can be used as a substitute for commercial fertilizers (Ndegwa et
al., 1991). Several researchers have reported that the chicken litter when applied to
the soil as an organic amendment will lower the densities of plant parasitic nematodes
(Gonzales and Canto-Saenz, 1993; Owino and Waudo, 1995; Riegel et al., 1996;
Riegel and Noe, 2000; Ravichandra et al., 2001; Ribeiro et al., 2002; Ami and Al-
Sabie, 2004). This suppression of nematodes is probably a combination of enhanced
microbial activity and constituent toxicity. The majority of nitrogen in poultry manure
is in the form of uric acid that can be rapidly converted to ammonium nitrogen if
temperature, pH and moisture are suitable for microbial activity (Sims and Wolf,
1994). The ammonia produced has been shown to kill plant parasitic nematodes (Eno
et al., 1993). The presence of pine shavings in litter serves as a carbon source and
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reduces phytotoxicity caused by the accumulation of ammonia and nitrates (Huebner
et al., 1983).
The addition of the agro-industrial wastes to the soil can exert a remarkable
suppressive action on phytonematodes (D’Addabbo, 1995). The release of toxic
compounds, performed or derived from the degradation of the wastes in the soil,
and/or the multiplication of nematode predators and/or parasites on the organic
substrate are supposed to be the fundamental mechanisms of this nematicidal action
(Stirling, 1991). Moreover, many of the currently available nematicides besides being
often costly offer no long-term suppression and having differential effects on the
species of nematodes as their activity is affected by many environmental factors
(Schmitt, 1986; Starr et al., 2002).
Akhtar and Mahmood (1996) reported that amending the soil, naturally
infested with different plant-parasitic nematodes, with cellulosic wastes and other
waste materials such as oil seed cakes, chitin, compost, livestock and poultry
manures, can be effectively employed against the damage caused by these plant
parasitic nematodes.
Addition of fly ash into the soil cause changes in its physical and chemical
characteristic and is supposed to increase concentration of carbonates and
bicarbonates (Khan and Khan, 1996). The reduction in the number of galls per plant
was very high with nematode inoculated plants grown at 10 and 20% fly ash levels, as
against M. incognita inoculated plants alone (Azam et al., 2007). Pasha et al. (1990)
reported decreased soil population of M. incognita at 10-100% fly ash levels. Niyaz
and Hisamuddin (2010) observed suppression in the morphmetrics of M. incognita
females and egg mass production with increasing fly ash levels.
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The soil application of organic amendments viz., vermicompost, neem cakes,
castor cakes, groundnut cakes, sunflower cakes and FYM have significantly reduced
the nematode population and increased the plant growth compared to inoculated
control (Jagadeeswaran and Singh, 2011). Compost is an organic matter resource
resulted from exploiting wastes through the controlled bioconversion process. It
seems to meet the objectives of the alternative agriculture system and the growing
consensus of both environmentalists and those concerned with the public health
through solving the waste disposal problem and its application in sustainable
agriculture instead of ecologically undesirable mineral fertilization (Ndiaye et al.,
2000; Madejon et al., 2001; Melero et al., 2007; Courtney and Mullen, 2008;
Chitravadivu et al., 2009).
Vermicompost is a new form of organic soil amendment that has considerable
potential in crop production. Vermicompost has large surface areas that provide many
micro sites for microbial activity and for the strong retention of nutrients.
Additionally, vermicompost have been reported to have outstanding biological
properties and have microbial populations that are significantly larger and more
diverse compared with those of conventional thermophilic composts (Edwards, 1998).
Vermicompost and goat manure were significantly better alternatives in eco-
friendly management of M. incognita and they induce the growth of seedling of
tomato at its early stages due to high amount of nitrogen (1.94% in vermicompost and
4.9% in goat manure) which is important for plant growth (Pakeerathan, et al., 2009).
The organic matter amendments significantly improved plant growth of groundnut
and reduced the disease infection by phytonematodes. Fresh Azolla ranked the best in
improving plant growth and reducing host infestation significantly. Dry Azolla is also
improving plant growth against plant parasitic nematodes (Joshi and Patel, 1995).
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2.2.2. Oil cakes and Green manuring
Many neem preparations, including leaves, oil cakes and kernel oils have been
tested for their nematicidal activity (Akhtar, 2000a) and the insecticidal limonoids
from kernel oils, including azadirachtin, nimbin and salannin have been reported to be
the main nematicidal compounds as well (Akhtar, 2000a). A neem extract containing
10% azadirachtin was nematicidal to Meloidogyne javanica juveniles in alkaline
sandy soil (pH 8.5) at concentrations higher than 0.05 g kg-1
, or at higher than 0.17 g
kg-1
for its formulation (Oka et al., 2007).
Oka et al. (2000a) reported that twelve of twenty seven essential oils extracted
from spices and aromatic plants immobilized more than 80% of juveniles of root-knot
nematode, M. javanica at a concentration of 1000 l/litre and at the same
concentration most of these oils also inhibited nematode hatching. The essential oils
of Carum carvi, Foeniculum vulgare, Mentha rotundifolia and Mentha spicata
showed the highest nematicidal activity in vitro and those from Origanum vulgare,
O. syriacum and Coridothymus capitatus reduced root-galling of cucumber seedlings
when mixed with sandy soil.
Many essential oils of medicinal plants and herbs have been reported
nematicidal (Oka et al., 2000a; Park et al., 2005), but the effect of their plant
materials when incorporated into the soil has not been well studied. Soil amendments
with several oriental herbal medicines at 0.2% (w/v) reduced M. incognita infection
on tomato (Kim et al., 2003).
In reducing the nematode population associated with Pomegranate by oil
cakes, are in agreement with Singh and Sitaramaiah (1970). The oil cakes apart from
contributing to NPK are greater benefit in the agriculture, which none of the synthetic
fertilizer or pesticide can offer. They provide slow and steady nourishment protection;
Review of Literature
47
create antagonistic conditions for pathogens including soil nematodes (Khan et al.,
2011). Oil cakes retard nitrification of the soil/urea and thereby increase N uptake by
the plants (Tiyagi et al., 2002) oil cakes containing 2-7% of protein N applied at @ of
4-10%suppress soil nematodes and improve plant tree health.
Abd-Elgawad and Omer (1995) explored the essential oils of four medicinal
plants for phytonematode control. All the oils inhibited nematode mortality but
Mentha spicata was generally more effective in reducing the number of active
nematodes followed by Thymus vulgaris, Majorana bortensis and Mentha longifolia.
Soil stages of the reniform nematode were more affected by the oil than those of the
ring and lance nematodes. The content of oxygenated compounds in these oils ranged
from 45.79% to 96.50% and may be partially responsible for the nematicidal effects.
Pandey (2000) reported the nematicidal activity of eight essential oils against
root-knot nematode, M. incognita at four different concentrations viz., 2000, 1000,
500 and 250 ppm. Maximum nematicidal activity was recorded in oils of Eucalyptus
citriodora, E. hybrida and Ocimum basilicum followed by Pelargonium graveolens,
Cymbopogon martini, Mentha arvensis, Mentha piperata and Mentha spicata oils
respectively, however, eucalyptus and Indian basil oils were highly toxic even at
lower concentrations (500 and 250 ppm).
Green manuring is an essential and age old practice of Indian farmers as well
as the farmers throughout the world, wherein the green plants/plant parts are ploughed
deep into the soil to rot and provide nutrient for succeeding crops, however, it has also
been found to reduce the populations of plant-parasitic nematodes. It was Lindford et
al. (1938), for the first time who reported that incorporating chopped pineapple leaves
@50-200 tonnes/acre into the soil significantly reduced the root-knot incidence in
cowpea. The infested soil when amended with chopped cabbage leaves (Brassica
Review of Literature
48
oleracea capitata L.) @ 680g/0.61m2, reduced the cereal root eelworm (Duddington
and Duthoit, 1960; Duddington et al., 1961). Hutchinson et al. (1960) noticed that the
population of some plant-parasitic nematodes like Hoplolaimus, Pratylenchus and
Tylenchorhynchus spp. were significantly lower in the soil where pieces of pumpkin
(Cucurbita pepo L.) were allowed to rot compared with the rest of the soil. Mankau
(1968) found that the application of alfalfa (Medicago sativa) green manure in root-
knot infested field was found to be a good nematode suppressant. The application of
rapeseed green manure @200, 300 and 400 mg N/kg soil was more effective than
velvet bean green manure in reducing root-galling caused by M. arenaria in squash
roots (Crow et al., 1996). Sudangrass has been reported to suppress infection and
damage caused by M. hapla, when incorporated as a green manure (Widmer and
Abawi, 2000). This addition of green manures stimulates soil microbial activities and
increases accumulation of plant decomposition products and microbial metabolites
that can be deleterious to nematodes.
Alternatively, Djian-Caporalino et al. (2002) identified 39 species of green
manures that belong to 22 botanical families, including peanut (Arachis hypogaea),
basil (Ocimum basilicum), cotton (Gossypium hirsutum), sesame (Sesamum
orientale), oat (Avena sativa) and rye (Secale cereale). But the most efficient were
sudangrass and sorghum (Sorghum sudanense), cruciferae, like oil radish (Raphanus
sativus) and rapeseed (Brassica napus), ricin (Ricinus communis), marigold (Tagetes
erecta, Tagetes patula, Tagetes minuta), Juglans regia, and velvet bean (Mucuna
deeringiana) (Crow et al., 1996; Bridge, 1996; Al-Rehiayani and Hafez, 1998;
Widmer and Abawi, 2002; McKenry and Anwar, 2003; Everts et al., 2006).
Review of Literature
49
2.2.3. Nematicidal activity of plant extracts
Many plants possess nematicidal and nematostatic properties in their roots,
shoots, leaves, flowers, seeds and their extracts, essential oil, oil seed cake and
derivatives. Some of the plant species and parts antagonistic to Meloidogyne spp. are
leaves and flowers of marigold (Tagetes sp.), leaves, roots and seeds of neem
(Azadirachta indica), leaves and seeds of chinaberry (Melia azedarach) (Rather et al.,
2007). Essential oils and plant extracts of sweet wormwood (Artemisia obsinthium),
thyme (Thymus vulgaris), peppermint (Mentha spicata), fennel (Foeniculum vulgare),
garlic (Allium sativum) and Eucalyptus spp., were toxic and reduced hatching activity
of phytonematodes (Ibrahim et al., 2006). Among these plants, marigold (Tagetes sp.)
is the most commonly studied. As marigold belongs to the Asteraceae, it is possible
that other members of the family may also possess antagonistic properties against
plant-parasitic nematodes (Tsay et al., 2004). Neem (Azadirachta indica) is one of the
most common nematicidal plants that were recognized in the middle of the 20th
century. Simple home made products like neem seed powder, neem seed kernel
powder, neem seed cake powder, dry neem leaf powder and the appropriate aqueous
extracts made from neem are available (Javed et al., 2006).
Plants appear to be a source of effective pesticide compounds and may be
regarded as an inexhaustible source of harmless pesticides having a low plant and
human toxicity and being easily biodegradable (Prakash and Rao, 1997).
Consequently, a large number of plants/plant parts/plant products have been screened
for their nematicidal activities (Pandey, 1990; Eyal et al., 2006). Although most
researchers have investigated the non-volatile constituents of the plants for their
nematotoxic potential (Sangwan et al., 1990; Ghosh and Sukul, 1992), but little
Review of Literature
50
attention has been given to volatile constituents of essential oil-bearing plants
(Kochhar, 2006).
Meena et al. (2010) reported that acetone extracts of leaf, flower, roots and
stem of five different varieties of Tagetes were found to be highly effective in causing
mortality of juveniles and inhibition of egg hatching. Acetone extract of T. erecta cv.
Indian Yellow was found to be highly effective in suppressing M. incognita. The
medicinal plants are showing the nematicidal properties so they are widely used for
the control of plant parasitic nematodes.
Joymadidevi (2010) reported that the nematicidal effect of medicinal plants as
chloroform methanol extract on egg hatching and larval mortality of M. incognita
were very effective. The rate of hatching was directly proportional to the
concentration of extracts. Several plants, belonging to different botanical families,
contain principles possessing nematicidal or nematostatic properties (Grainge and
Ahmad, 1988). Khanna and Kumar (2006) reported that the effect of five neem based
pesticides on the mortality of juveniles and egg hatch of M. incognita. Recently many
workers used plant extract showing nematicidal properties for seed treatment or bare
root dip treatment. The applications of methanolic extract of botanicals are very
effective in the control of phytonematodes (Usman and Siddiqui, 2011a, 2012b).
Many researchers used different plant extracts as a seed treatment or bare root
dip treatment for the control of M. incognita and other nematodes (Siddiqui and
Alam, 1988a, b; 1989a, b). Hussain et al. (1984) showed that root dip treatments of
eggplant seedling with Margosa and Marigold leaf extracts considerably reduced root
knot nematode development as compared to treatment with Cina, Piprazine citrate,
Chenopodium oil and Ground nut cake. Abid and Maqbool (1991) showed bare root
dip treatment in the leaf extracts and neem leaves significantly reduced root-knot
Review of Literature
51
infection caused by M. javanica on tomato and egg plant. The damaging effects of the
nematode were masked by bare root dip treatments as shown by improved plant
growth in both the test plants. Usman and Siddiqui (2011a) evaluated the leaf extracts
of Murraya koenigii L. and Vitex negundo L. as bare-root dip treatment for the
management of M. incognita infecting tomato (Lycopersicon esculentum) and chilli
(Capsicum annum) plants. Significant reduction was observed in the root-knot
development caused by M. incognita on the experimental plants. Leaf extracts
of Murraya caused relatively higher inhibition in root-knot development and
nematode multiplication than Vitex.
Various compounds such as nimbin, nimbidin, azadirachtin, salannin,
thionemon and meliantriol occur in the seeds, leaves and bark of neem in high
concentrations (Kraus,1995) and are responsible for the antimicrobial and nematicidal
activity (Eppler,1995). Powder from the seed kernels and leaves has been found to be
suppressive against some nematodes (Alam, 1993). Tiyagi et al. (2009) studied the
effect of leaf extracts of two latex-bearing plants such as Calotropis procera and
Thevetia peruviana as a bare-root dip treatment for the management of
phytonematodes, M. incognita and R. reniformis infecting tomato and plants. A
significant reduction was observed in the root-knot development caused by M.
incognita and nematodes multiplication of R. reniformis on the experimental plants.
Khan et al. (2011) showed that the curative effect of plant extracts viz., neem,
tobacco, Aloe vera, chilli, clove, garlic and onion against M. incognita. Similarly
significant reduction was observed in the population of plant-parasitic nematodes, M.
incognita, R. reniformis and T. brassicae infesting eggplant and cauliflower, when the
seedlings were given the root-dip treatment in leaf extracts of Argemone maxicana
and Solanum xanthocarpum (Ajaz and Tiyagi, 2003).
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52
In addition to this, a number of indigenous plants have been reported to
possess nematicidal/nematostatic properties and thus, are capable of managing the
populations of various plant-parasitic nematodes (Zarina and Shahina, 2010). Some of
these plants tested for their antinemic properties by different workers include Abutilon
indicum, Solanum forskalii, S. nigrum and Xanthium strumarium (Shaukat and
Siddiqui, 2001). Allium cepa, Aloe vera, Calendula officinalis, Capsicum annuum,
Syzygium aromaticum and Nicotiana tabacum (Khan et al., 2008a), Asparagopsis
taxiformis (Rizvi and Shameel, 2006a), Avicennia marina (Tariq et al., 2007).
Azadirachta indica, Fresh leaves, extract, ethanolic extract, dry leaves powder, seed,
seed decoction, oil cake, product, oil, derivatives and formulation (Javed et al., 2007a,
b; Jiskani et al., 2005), Azadirachtin, Neem formulation (Javed et al., 2007c).
Bauhinia alba, Datura alba, seed decoction and Eucalyptus alba, leaves, bud, stem
and fruit (Pathan et al., 2002a). Bauhinia purpurea, Calotropis procera, Datura
fastuosa and Azadirachta indica (Zarina et al., 2003). Calendula officinalis,
Helianthus annuus, H. bipinnatus, Tagetes erecta and Zinnia elegans (Siddiqui et al.,
2005). Calotropis procera, extract of flowers, leaves, stem root and cake (Pathan et
al., 2002b). Cassia fistula, Daucus carota, Fumaria indica, Heliotropium
curassavicum, H. tuberculosum, Hibiscus rosa sinensis, Justicia adhatoda, Lactuca
remotiflora, Melia azadirachta, Mimosa hamata, Withania somnífera, S. surattense,
Euphorbia hirta and E. tirucalli (Abid et al., 1997). Catharanthus roseus
(Husan Bano et al., 1999); Cystoclonium purpureum and Iyengaria stellata (Rizvi
and Shameel, 2006b); Eclipta prostrata (Shaukat et al., 2004; Zarina et al., 2006).
Eucalyptus sp. (Dawar et al., 2007); E. camaldulensis, E. pulcherrima, F. religiosa,
Ficus benghalensis, F. elastica and Opuntia imbricata (Zurreen and Khan, 1984);
Jania capillacea, Sargassum binderi and Solieria robusta (Ara et al., 1996); Lantana
Review of Literature
53
camera (Ali et al., 2001; Shaukat et al., 2003); Nerium oleander (Aziz et al., 1995a);
Nigella sativa (Shajia and Shahzad, 1998); Ricinus communis (Ahmad et al., 1991);
Sargassum spp. (Ara et al., 1997); Schweinfurthia papilionacea (Khan et al., 1997,
Khurram et al., 1997); T. patula (Husn Bano, 1999; Siddiqui et al., 2005); Zingiber
officinale (Zareen et al., 2003); Linum usitatissimum and Brassica campestris (Butool
et al., 1998), Salvia spp. (Idowu, 1999), Parkia biglobosa (Umar and Jada, 2000),
Murraya koengii (Pandey, 2000), Catharanthus rosea and Ipomea fistulosa (Hassen
et al., 2003). Blechum pyramidatum, Stenandrium nanum, Furcraea cahum,
Ageratum gaumeri, Ambrosia hispida, Bidens alba, Calea urtricifolia, Acalypha
gaumeri, Croton chinensis, Tephrosia cinerea, Trichilia arborea, T. minutiflora,
Randia longiloba, R. obcordata and R. strandleyana (Cristobal-Alejo et al., 2006),
Parkia biglobosa and Hyptis spicigera (Jesse et al., 2006), Euphorbia tirucalli, E.
neriifolia, Nerium indicum, Thevetia peruviana and Pedilanthus tithymaloides
(Siddiqui, 2006b), Ficus benghalensis and F. virens (Ahmad et al., 2007a), Eclipta
alba, Phyllanthus niruri and Withania somnifera (Usman and Siddiqui, 2012c), P.
hysterophorus, N. plumbaginifolia, A. fatua, C. album, A. retroflexus, C. murale, A.
spinosus and O. corniculata (Usman and Siddiqui, 2012b) .
Recently, Bello et al. (2006) reported the inhibitory effect of water extract of
seed, leaf and bark of five plants viz., Tamarindus indica, Cassia siamea, Isoberlinia
doka, Delonix regia and Cassia sieberiana against the larval hatching of M. incognita.
The standard suspensions inhibited larval hatching by 97% while dilution of S/100
inhibited larval hatch by 3%. The solvent extracts of the plant species viz., Allophylus
cobbe, Lepisanthes tetraphylla, Sarcococca zeylanica and Hedyotis lawsoniae, were
among seven Sri Lankan plants which showed significant nematicidal activity against
M. incognita maintained on tomato plants (Jayasinghe et al., 2003).
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54
2.3. PHYSICAL CONTROL
Soil solarization
Solarization traps solar radiation with transparent plastic films placed on the
soil to maximize conversion of heat. First reported by Katan et al. (1976) solarization
has been widely studied. Solarization increases soil temperature by 2-15 0C in warm
climate conditions. Its efficacy depends on the combination of soil temperature and
duration. M. incognita second-stage juveniles were completely killed in a water bath
heated above 38 0C; it took 48 h at 39
0C, but only 14 h at 42
0C (Wang and
McSorley, 2008). Soil solarization with plastic mulches leads to lethal temperatures
which kill plant parasitic nematodes (around 45 0C) and is being used mainly in
regions where high levels of solar energy are available for long periods of time
(Whitehead, 1998). The effect of this approach is reduced with depth, but solarization
for at least 4-6 weeks will increase soil temperatures to about 35-50 0C to depths of up
to 30 cm and, depending on soil type, soil moisture content and prior tillage, will
reduce nematode infestations significantly (Viaene et al., 2006). In Japan and other
East Asian countries, several farmers growing successive crops, such as tomato and
melon susceptible to root-knot nematodes have used solarization in plastic tunnels for
30 days in the summer as an alternative to methyl bromide fumigation (Sano, 2002).
In Cuba, root knot nematode infestations are reduced, in peri-urban and small
organic farm production, using solarization under sub-optimum conditions (Fernandez
and Labrada, 1995) but for subsistence agriculture, the cost of plastic sheeting may be
limiting. The length of time required for effective solarization is a great limitation too,
but it could be reduced when it is used with biofumigation. Infection of M. javanica
by P. penetrans was increased in naturally infested soils in a South Australian
vineyard treated by solarisation and decreased in soils treated with the nematicides
Review of Literature
55
oxamyl or phenamiphos but the bacterium did not significantly reduce nematode
populations (Walker and Wachtel, 1988). Similarly, in a cucumber crop in a
glasshouse trial the use of solarization and P. penetrans had an additive detrimental
effect on M. javanica populations (Tzortzakakis and Goewn, 1994). This physical
management was used for the control of root-knot nematode when black and
transparent polyethylene sheet single and double layer is spread on the soil surface for
different duration (Javed, 1992; Javed et al., 1994, 1997).
Soil solarization showed the best potential for reducing Meloidogyne spp and
other soil borne pathogens as it is easy to apply, pollution free , economical and
inexpensive (Calabretta et al., 1991a, b). Soil solarization with different thickness of
polyethylene sheets was very effective in reducing nematode population in the soil
this could be due to the fact that soil covered with polyethylene sheets reduces the
heat convection and water evaporation from the soil to atmosphere results in
formation of water droplets in the inner surface of polyethylene sheets, its
transmittance to long wave radiation is highly reduced resulting in better heating of
the soil (Grinstein et al., 1979; Katan, 1981; Abdel Rahim et al., 1988; Mazza et al.,
1994; Reddy et al., 2001).
The soil solarization also increases the temperature appreciably and the
thinnest polyethylene sheet proves to be efficient to increase the temperature and
better in heating, radiation and transmittance than the thicker one (Aguilar et al.,
1990; Siddiqui and Saxena, 1992; Ostrec, 1993; Siddiqui et al., 1997, 1998).
Soil solarization has been done by heating the soil beneath clear plastic mulch
for 6 weeks so that it reaches temperatures detrimental to soil borne pests
(Katan et al., 1976). This method has been used successfully against plant-parasitic
nematodes and soil-borne pathogens in several crops and regions around the world,
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56
especially in hot climates (Katan, 1976, 1981; Stapleton and Devay, 1983)
Approximately 14 hours at 42 °C temperature was sufficient to kill all root-knot
nematodes in sand tubes, but at sub lethal temperatures (40-42 °C) at least 46 hours
were required to kill them all (Wang and McSorley, 2008). Previous research verified
that sunnhemp consistently increases the number of beneficial free-living nematodes
in the soil (Wang et al., 2001, 2002, 2003) but that soil solarization temporarily
suppresses the beneficial organisms (Wang et al., 2006). However, integrating soil
solarization with a leguminous cover crop could reduce the negative impact of soil
solarization on beneficial soil organisms while improving the pest-suppression effect
achieved by cover cropping alone (Wang et al., 2006).
Integration soil solarization with other nematode management viz., organic
soil amendment, ploughing and chemical treatment may have a much more adverse
effect on nematode population (Siddiqui and Saxena, 1992). It has been reported that
the integrated effect of green manuring, organic amendment and soil solarization are
very effective in controlling phytonematodes (Wang et al., 2001; Hooks et al., 2006).
2.4. CHEMICAL CONTROL
The primary advantage of chemical control is that the nematode population is
reduced drastically to very low level within a matter of days after chemical applied.
Most crops are especially vulnerable to nematode attack during seedling stage when
the young root system is becoming established. Crops planted in treated soil develop a
good root system so that usually in case of annual, the crop is matured before the
residual population of nematodes has increased to a damaging level (Haydock et al.,
2006). Seed treatment and nursery treatment offer minimum application of
nematicides in to the soil and provides nematode free seedlings. These means of
chemical control are safer and can be coined as an integral component of integrated
Review of Literature
57
nematode management (INM). Vegetable crops accounting for the greatest proportion
of nematicide use and Meloidogyne spp. as the target for approximately half of this
usage (Haydock et al., 2006).
2.4.1. Soil treatment in the main field/Nursery
Application of ethylene dibromide or ethylene dibromide + chloropicrin in
Phaseolus vulgaris, dibromo-chloropropane (DBCP) @ 6 kg in pigeon pea reduces
the soil population of R. reniformis (McSorley and Parrado, 1983; Sharma et al.,
1993). Application of Temik, thimet + nemaphose and nemaphose alone, Nemacur or
Nemacur-Disyston in cotton seedling effectively control R. reniformis population in
soil (Bost, 1985).
Application of fosthiazate 6 or 12 pt/acre before or after bed preparation of
fields of sweet potato increased the yield by 15.6 and 88.9 lb/acre (Mclean and
Lawrence, 1996). Hadian et al. (2011) reported that drenching of soil with bavistin
(0.1%) completely eradicate the nematode population. Combinations of deep
ploughing (up to 20 cm) and nursery bed treatment with aldicarb at 0.4 g per m2 and
main field treatment with aldicarb at 1kg a.i./ha proved effective in the control of
root-knot nematodes in tomato which also registered maximum yield (Jain and Bhatti,
1985). In tomato, application of aldicarb and carbofuran each 1 Kg a.i./ha and in
combination with neem cake and urea each at 10 kg /ha, at transplanting, produced a
maximum yield with lowest gall index (2.5) and nematode population, 90 days after
planting (Routaray and Sahoo, 1985).
Carbofuran has been reported to control nematodes (Di sanzo, 1973). Low
galling index in soybean plants treated with carbofuran by both soil drench and soil
drench + foliar application has been reported (Ajayi et al., 1993). Furthermore it has
been reported that the application of 700 ppm on soyabean plants as soil drench
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58
reduced the number of M. incognita eggs that hatched into juveniles (Ajayi et al.,
1993). In an experiment where carbofuran 3G was applied at the rates of 0, 100, 200,
and 300 kg/ha to three hybrid yam varieties in southwestern Nigeria (Adegbite and
Agbaje, 2007) there was an increase in the yield of the three hybrid yam varieties,
which was significantly higher than in the control. The use of carbofuran at planting
was the most effective application timing to reduce M. javanica population levels
(Jada et al., 2011). Many workers (Patel and Patel, 2009; Jada et al., 2011) reported
the effect of nematicides alone and in combination with other management practices.
Similarly efficacy of carbosulfan as soil drench has been reported by Prasad and
Narayana (2000) in sunflower and, Garabedian and van Gundy (1985) in tomatoes
against root-knot nematode. Although chemical agents like carbofuran are efficient in
controlling nematodes (Adegbite and Agbaje, 2007), their persistence may pose
ecological problems (Li et al., 2008). The effectiveness of granular application of
carbofuran and phorate against root-knot nematode of okra has been reported by
several workers (Sitaramaiah and Vishwakarma, 1978; Khair et al., 1983; Sultan and
Singh, 1987; Sheela and Nair, 1988; Jadhav, 1989; Jain, 1990; Gul et al., 1991).
However, Ahmad and Sultana (1981) found that carbofuran was less effective than
aldicarb granules in gall formation. Next effective seed treatments were carbosulfan
and acephate which supported the findings of Patil (1991) and Kathirvel et al. (1992)
who reported its effectiveness as seed treatment and their impact on promoting growth
parameters. Similarly, the effectiveness of seed treatment with acephate was
promising in cotton as reported by Dhoot (1990) and in french bean (Mohan and
Mishra, 1993).
Mishra et al. (1987) also observed that carbofuran at 1 kg a.i./ha was effective
in reducing the nematode population (J2) and increasing fibre yield of jute.
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59
Similarly, Senapati and Ghosh (1992) also recorded greatest suppression of root-knot
nematode infestation in jute with the application of carbofuran at 2 kg a.i./ha under a
jute-paddy rotational system. This treatment increased fibre yield by 28% even with
the highest initial soil population density of the nematodes (Khan, 2004).
Many workers tested various nematicides on M. incognita and on the growth
of tomato were in conformity with Minton et al., (1993), Lawrence and McLean
(1995), Giannakou et al., (2005) and Hafez and Sundararaj (2006). These authors
reported that fosthiazate provided excellent control of root-knot nematodes and
increased plant growth and yield. In addition, cadusafos and fosthiazate reduced M.
arenaria population on winter-grown oriental melon from 35 to 90 % compared with
control (Kim et al., 2002). However, fosthiazate was better than cadusafos and
fosthiazate pre-plant plus post-plant application and reduced nematode population
densities as much as 90 % and increased yield (Kim et al., 2002). Carbofuran gave
reduction in the incidence of root-knot nematodes infecting different vegetable crops
(Radwan, 1995; Stephan, 1995; Badawi and Abu-Gharbieh, 2000; Bari et al., 2004b;
Bhat et al., 2005; Singh et al., 2006). Giannakou et al. (2005) reported that oxamyl
provided some nematode control while cadusafos failed to provide adequate nematode
control, which may be attributed to the inability of the nematicide to reduce nematode
populations even at relatively high concentrations in soil.
Developing any new marketable nematicide is a long and expensive process
and reports state that no new widespread used nematicide has been developed in the
past 20 years (Starr et al., 2002). The worldwide phase-out of methyl bromide (one of
the effective and widely used fumigant nematicide (Oka et al., 2000b) and the
extreme cost of bringing new nematicides into the market triggered the need for the
alternative nematode control strategies that are economically feasible and
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60
environmentally acceptable even if these strategies cannot compare to the 100%
efficacy of methyl bromide.
2.4.2. Seed treatment
Seed treatments gave adequate initial protection from nematode larvae to
seedling to better plant growth and increased yield. Cotton seed treated with
nematicides viz., carbofuran, phorate and fensulfothion can effectively be employed
to reduce population of R. reniformis from 32.45 to 49.06% (Muralidharan and
Sivakumar, 1975). Abamectin is a mixture of macro cyclic lactone metabolites
produced by the fungus Streptomyces avermitilis, which used as a seed treatment to
control plant parasitic nematodes on cotton and some vegetable crops. Abamectin was
effective on both M. incognita and R. reniformis in tomato plants (Faske and Starr,
2006). Abamectin has also a nematicidal effect against M. incognita and R. reniformis
on cotton plants as a seed treatment (Faske and Starr, 2007).
Furthermore, abamectin proved highly activity against lesion nematodes
(Pratylenchus spp.) as a seed treatment on corn with reduction evaluated by 25-72%
(Cochran et al., 2007). Seed treatment with carbofuran @ 0.1% in cotton and
1kg/100kg in mungbean were effective in reducing soil and number of eggs/plant of
R. reniformis (Brancalion and Lordello, 1982; Patel and Thakar, 1986). Korayem et
al. (2008) found that abamectin at the tested concentrations significantly reduced most
nematode parameters and enhanced plant growth parameters.
The protective and curative application of the biopesticides especially
abamectin and then azadirachtin were found effective in reducing the invasion of the
J2 and their further development in the roots. Azadirachtin was able to induce defence
mechanism in roots of plants, which consequently delayed the nematode development
(Rehman et al., 2009).
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61
Reduction in gall numbers and final nematode population with nematicides for
12 h seed soaking has been recorded (Das and Deka, 2002; Deka et al., 2003). Earlier
several studies have proved the efficacy of carbosulfan and neem seed kernel powder
as a seed treatment in suppressing the phytonematodes in many field crops viz.,
chickpea (Chakrabarti and Mishra, 2001). Many workers (Singh et al., 1980; Siddiqui
and Alam, 1988a) demonstrated the application of Azadirachtin as the coating agent
which significantly reduced the root knot development.
Applications of nematicides as seed treatment or seed-cum-soil application
were found to give better control (Khan, 2004). Among the nematicides, fenamiphos
2kg a.i./ha was the most effective as it increased fibre yield of jute by 68%, being
particularly effective when the initial population of the nematode in soil was
relatively low. This was followed by carbofuran at 2 kg a.i./ha, which gave up to 40%
and 47% increase of fibre yield when applied to soil alone and in combination with
carbosulfan as seed treatment respectively (Khan, 2004). Mahanta et al. (1992)
found that soaking jute seed in a solution of carbosulfan 0.2% reduced root galling
and egg mass production of M. incognita. However, combining carbosulfan as seed
treatment with soil application of phorate at 2 kg a.i./ha and sebuphos at 2 kg a.i./ha
provided higher yields when they were applied alone (Khan, 2004). The application
of Nimbin as seed dressing significantly reduced the root-knot development,
populations of R. reniformis and T. brassicae (Siddiqui and Alam, 1990).
2.4.3. Seedling bare root dip treatment
Nematode damage is more harmful to seedling than to older plants. Hence
treatments with nematicides applied only at seedling roots may, therefore, lessen
nematode damage and may be more economical. Bare root dip treatment of brinjal
seedling with aldicarb, carbofuran, and terbofos at 500 and 1000 ppm was effective in
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reducing nematode population (Prasad and Krishnappa, 1981). Bare root dip treatment
with pyridoxine hydrochloride (vitamin B6) solution of 0.1, 0.3 or 0.5% concentration
for 30 minutes resulted in improved plant growth (Ahmad and Alam, 1997).
Chemicals tested in the bare root treatment were induced some resistance in tomato
and eggplant against M. incognita and R. reniformis (Siddiqui, 1998). The poor root
knot development could be attributed to poor penetration (Siddiqui and Alam, 1988a)
and later retardation in different activities of the second stage juveniles such as
feeding and /or reproduction as suggested by Bunt (1975). This phenomenon might
have also happened in the case of R. reniformis where the plants did not support the
multiplication of the nematode as freely as compared to those which were not
subjected to root-dip treatment (Siddiqui, 1998).
It is possible that the chemicals are either absorbed by the roots or there might
have been some chain reaction which has been triggered due to some factor
(elicitor/activator). The initiation of the cascade mechanism leading to the resistance
of cells against the invasion and development of pathogens has been earlier described
(Bunt, 1975; Bell, 1981; Giebel, 1982). Bell (1981) considered the role of nematode
and plant enzymes in resistant plant reactions and suggested that enzyme effected
changes in growth regulators, free bound phenols, amino acid composition, and
induced lignifications to limit nematode development. Efficacy of carbofuran on
Meloidogyne as root dip treatment was reported by Gowda et al., 1988.
Application of a nematicide is required in each growing season of a
susceptible crop. Nematicide persistence in soil for 6-8 weeks is desired for effective
initial plant protection (Karpouzas et al., 1999). A few nematicides exist and currently
are not used for control of nematodes in India. Several insecticides used for insect
control, such as carbofuran, carbosulfan, cadusafos, phorate, and triazophos, possess
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nematicidal activity, of which cadusafos has been reported to be the most effective
(McClure and Schmitt, 1996; Karpouzas et al., 1999; Le Roux et al., 2000; Meher et
al., 2005).
2.5. BIOLOGICALCONTROL
A variety of organisms have been shown as a potential biological control agent
of phytonematodes. This includes fungi, bacteria and virus etc. The beneficial effects
of certain types of plant derived materials and microorganisms in the soil have been
attributed to a decrease in the population densities of plant parasitic nematodes
(Akhtar, 2000b). Plant associated microorganisms have important roles in natural and
induced suppressiveness of soil-borne diseases. Several culturable rhizobacteria have
been tested for their biocontrol potential against plant parasitic nematodes (Siddiqui
and Shaukat, 2002, 2003; Khan et al., 2008b; Son et al., 2008, 2009). Addition of
treatments with plant extracts, bacterial suspensions or Vydate into soil suppressed
root galling and final populations of M. incognita, and except for Vydate promoted
plant growth and yield (Abo-Elyousr et al., 2010). Biological control organisms can
be artificially introduced into the soil, but naturally occurring soil microorganisms can
be stimulated by the addition of organic materials. There are now enough reported
examples of natural biological control of nematodes to show that this is a widely
occurring and common phenomenon (Bridge, 1996; Ahmad and Khan, 2004).
Biocontrol agents improve the health of plants and thus contribute to overall
productivity. These agents are also self propagating under favourable conditions and
therefore, may remain in the soil for a long period. Therefore, biocontrol is suggested
to be a safer solution. Various fungal antagonists of nematodes have shown promising
results. These mainly include endoparasitic fungi, parasites of nematode egg and
nematode trapping fungi. The fungus, P. lilacinus, is an egg parasitic fungus which
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infects by direct hyphal penetration. The hyphae branch grows across the egg shell
(Khan et al., 2006).
The egg pathogenic fungus P. lilacinus is one of the most widely tested soil
Hyphomycetes for the biological control of plant parasitic nematodes
(Atkins et al., 2004). Lara Martez et al. (1996) demonstrated that P. lilacinus
significantly reduced M. incognita soil and root populations and increased yield of
tomato. (Siddiqui et al., 2000) has reported the reduction of M. javanica infection on
tomato by P. lilacinus. Cannayane and Sivakumar (2001) reviewed the biocontrol
efficacy of P. lilacinus and listed several reports where root-knot nematodes and the
potato cyst nematode Globodera rostochiensis were successfully controlled by this
egg-pathogenic fungus.
The culture filtrate of the Trichoderma species was highly significant in
controlling both nematode genera on eggplant. T. harzianum, T. hamatum and T.
koningii culture filtrates gave a significant reduction in vitro and decreased the female
and eggmasses of reniform and root-knot nematodes (Muthulakshmi et al., 2010;
Usman and Siddiqui, 2012a). Trichoderma culture filtrate was more significant on
root-knot nematode, M. incognita (Priya and Kumar, 2006). Trichoderma controls
nematode genera by a direct effect on toxic metabolites and inhibits nematode
penetration and development (Bokhari, 2009). Root colonization by Trichoderma spp.
frequently enhances root growth and development, crop productivity, resistance to
abiotic stresses and uptake and use of nutrients (Harman et al., 2004).
The Trichoderma species had been previously reported in the literature as
strains of T. harzianum and were reidentified (Rocha-Ramirez et al., 2002). These
species were used before nematode biocontrol studies (Sharon et al., 2001). Haseeb et
al. (2005) reported that the M. incognita-Fusarium oxysporum disease complex can
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cause severe yield losses in V. radiata as in other crops. Although chemicals viz.,
carbofuran and bavistin showed a significant effect in increase of growth parameters
and in suppression of the disease complex, these can be replaced to some extent by A.
indica seed powder and microbial antagonists viz., T. harzianum and P. fluorescens to
avoid the hazards of chemicals.
Among numerous organisms that have shown antagonism against root knot
nematodes, P. chlamydosporia (Kerry, 2000; Siddiqui, et al., 2009), P. lilacinus
(Jatala, 1985; Kiewnick and Sikora, 2006), and T. harzianum (Siddiqui and Shoukath,
2004; Bokhari, 2009) have been found to be highly suppressive to plant nematodes,
especially under greenhouse conditions (Khan, 2007). Combining P. lilacinus with
neem leaves can provide satisfactory control of root-knot disease in eggplant (Khan et
al., 2012).
Successful biocontrol combinations have been recorded against root-knot
nematodes. The combination of the bacterium Bacillus subtilis and the fungus
Paecilomyces lilacinus suppressed nematode populations beyond the individual
application of the agents (Gautam et al., 1995). The fungal bioagents viz., P. lilacinus
and Trichoderma viride alone or in combination with mustard cake and furadan
promoted plant growth, reduced number of galls/plant, egg masses/root system,
eggs/egg mass and nematodes reproduction factor as compared to untreated infested
soil (Goswami et al., 2006).
The maximum reduction in root galling and the soil population, occurred in
soil treated with both fungi in combination with mustard cake. T. viride used alone
responded least as compared to P. lilacinus which was also observed by Khan and
Goswami (2000). The fungi used in combination also increased the plant growth
(Goswami and Singh, 2004). Both the fungi along with mustard cake and furadan
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showed least a reproduction factor (0.0) as compared to untreated infested soil
(1.783). Goswami (1993) obtained a significant reduction in root gall index where soil
was treated with P. lilacinus with castor leaves and fertilizer.
Reddy et al. (1996) proved that T. harzianum incorporated into oil cakes was
effective for increasing yield and reducing the nematode numbers in soil and roots.
Other researchers (Siddiqui et al., 1999; Haggag and Amin, 2001;
Haseeb et al., 2005) studied the effect of Trichoderma on the development and
growth of parasitic nematodes. Stephan et al. (2002) reported that T. harzianum and
animal organic matters reduced the numbers of root-knot nematodes. Faruk et al.
(2002) indicated the effectiveness of T. harzianum on the biocontrol of root knot
nematodes on tomato. Saifullah (1996a, b) showed the death of 100% of Globodera
rostochiensis and G. pallida by using poisoning compounds from T. harzianum on the
medium after 24 h of exposure. It is well known that T. harzianum produces several
poisoning and antibiotic compounds (DiPietro, 1995) that can protect plants from
pathogenic organisms in soil (Wu and Wu, 1998). Several studies (Spiegel and Chet,
1998; Susan et al., 2000; Haggag and Amin, 2001; Sharon et al., 2001; Howell, 2003;
Siddiqui and Shaukat, 2004; Santhosh et al., 2005) showed the use of Trichoderma
for inhibiting the growth of plant parasitic nematodes. The secondary metabolites of
Trichoderma include chitinase enzyme which is considered to be the most effective
component against pathogenic fungi. Chitinase enzymes degrade the fungal cell walls
which are composed of chitin (Lorito et al., 1993). Chitin comprises the outer shell of
nematode’s eggs so that nematode eggs are affected greatly by Trichoderma species
treatment (Haggag and Amin, 2001; Jin et al., 2005).
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2.5.1. The combined effect of organic amendments and biological control
Large numbers of workers have demonstrated that use of organic soil
amendment with different biocontrol agents viz., T. harzianum, P. lilacinus etc.
Combined application of biocontrol agents with various oil cakes have been reported
to be an effective approach to minimize the loss caused by various phytonematodes
(Tiyagi et al., 2002; Borah and Phukan, 2004; Zareena and Kumar, 2005). Azam et al.
(2009) reported that the combination of leaf powder C. tora and P. lilacinus was
ascertained to be most effective in managing the root knot disease.
Ashraf and Khan (2010) evaluated the efficacy of biocontrol agents and
various organic amendments in the management of phytonematodes infecting
eggplant under glasshouse conditions. All the treatments effectively suppressed the
nematode population. P. lilacinus and green manuring of Zea maize and Sesbania
aculeata were very effective for the management of Rotylenchulus reniformis
(Mahmood and Siddiqui, 1993).
Fruit wastes of apple, banana, papaya, pomegranate and sweet orange @
20g/plant and the fungal biocontrol agent P. lilacinus @ 2g (mycelium+spores) /plant,
alone and in combination were very effective for the management of R. reniformis
(Ashraf and Khan, 2008). The combined application of P. lilacinus, carbosulfan,
poultry manure and FYM alone and in combination significantly increased the plant
growth parameters including yield and reduced the population of M. incognita (Das
and Sinha, 2005). The integrated application of certain botanicals and P. lilacinus is a
better approach in reducing the nematode population and increasing the plant growth
and yield when used alone (Zaki and Bhatti, 1990; Zaki, 1998; Walia and Gupta,
1997).
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Application of P. lilacinus showed better results in improving plant growth
and reducing the nematode population build up as compared to oil cake treated plants
whereas neem cake gave better results than other oil cakes. However, integration of
neem cake with P. lilacinus gave the best result causing increased plant growth and
reduced population build up of reniform nematode (Anvar, 2003; Ashraf and Khan,
2005). Research on nematode trapping fungi has demonstrated that the enhancement
of trapping activity resulting from the application of organic matter in soil is
dependent on the fungal species and the type and amount of organic material added
(Jaffee et al., 1994; Jaffee, 2004).
It is clear from the literature that the benefits of a combined green manure and
a microbial agent depend on the soil, the type of green manure and the species of
agent. The rhizosphere of some plants antagonist to plant parasitic nematodes have
distinct microfloras that have physiological traits, which indicate that at least part of
the antagonism may be due to the bacterial and fungal community on roots (Kloepper
et al., 1991; Insunza et al., 2002).
Kumar et al. (2011) and Haseeb and Kumar (2006) also reported that the
treatment with T. harzianum, P. fluorescens, A. niger, P. lilacinus, neem seed powder
and farmyard manure alone significantly decrease the severity of the infestation of M.
incognita and F. solani on brinjal. Perveen et al. (2007) reported that application of T.
viride and P. fluorescens with farmyard manure effectively control M. incognita and
plant growth. Similar results were also obtained by number of workers on other crops
(Pant and Pandey, 2002; Kumar et al., 2009; Abuzar and Haseeb, 2010). Combined
application of biocontrol agents, organic amendment and nematicides treatment was
found to be best among all treatments which significantly increased the growth
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69
parameters including yield and reduced the population of M. incognita (Das and
Sinha, 2005).
Goswami et al. (2006) observed that the maximum reduction in root-galling
caused by M. incognita on tomato plants, as well as the soil population occurred in
soil, treated with both fungi (T. viride and P. lilacinus) in combination with mustard
cake. However, mustard cake alone also showed adverse effects on the root-
nodulation. Bio management of root-knot nematode, M. incognita affecting chickpea
using non edible seed oil cakes is an effective and ecologically safer approach as a
substitute of nematicides for the pollution free and sustainable environment (Rehman
et al., 2012).
Integration of Paecilomyces lilacinus and carbofuran at 2 kg a.i./ha was found
to be effective in the management of reniform nematode, Rotylenchulus reniformis on
tomato (Reddy and Khan, 1988). Sundraraju and Kiruthika (2009) demonstrated that
the integration of P. lilacinus with neem cake or anyone of the botanicals viz.,
Tagetes spp., S. torvum, can be effectively used in the management of root knot
nematode, since the use of single bioagent or botanicals cannot be very effective in
the management of nematode induced disease complex. The combined application of
various oil cakes and biocontrol agents have been reported to be an effective approach
to minimize the losses caused by various plant-parasitic nematodes (Mahmood and
Siddiqui, 1993; Rao et al., 1995; Tiyagi et al., 2002; Borah and Phukan, 2004;
Zareena and Kumar, 2005).
Ahmad and Khan (2004) reported that the amendments of neem sawdust and
kail sawdust were more or less equally effective to M. incognita infecting chilli and
did not differ significantly. The combined application of neem sawdust with the
biocontrol fungus P. lilacinus was more promising in increasing the plant growth and
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decreasing the reproduction factor and root-galling, however, the kail saw dust did not
significantly increase the efficacy of P. lilacinus as the parasitism of the fungus was
inhibited and resulted in lower infection only on the egg masses of root-knot
nematode, M. incognita. The inhibitory effect of kail sawdust on the parasitism of P.
lilacinus could in fact be due to the toxic principles contained in kail sawdust and
released in soil, which might have inhibited the activity of P. lilacinus.