Diseases CoveredDiseases Covered

Rhizoctonia Crown Rot and BlightRhizoctonia Crown Rot and Blight Botrytis BlightBotrytis Blight Black SpotBlack Spot Daylily Rust Daylily Rust

Rhizoctonia crown and root rot.Rhizoctonia crown and root rot.

Caused by Caused by Rhizoctonia solaniRhizoctonia solani Root rot may develop either in the rooting Root rot may develop either in the rooting

cube or on rooted cuttings transplanted to cube or on rooted cuttings transplanted to pots as the crop is finished for retail. Infected pots as the crop is finished for retail. Infected roots become water-soaked then brown. roots become water-soaked then brown.

Both root tips and sections of the root away Both root tips and sections of the root away from the tip may develop symptoms. Crown from the tip may develop symptoms. Crown rot can develop on the stem as lesions rot can develop on the stem as lesions expand from stem infections occurring during expand from stem infections occurring during propagation. propagation.

Stem lesions may develop at a much slower pace on Stem lesions may develop at a much slower pace on rooted plants, since this tissue is more hardened off and rooted plants, since this tissue is more hardened off and thus more resistant than stems of newly made cuttings. thus more resistant than stems of newly made cuttings.

Foliar symptoms of crown and root rot include chlorosis, Foliar symptoms of crown and root rot include chlorosis, leaf necrosis, wilting, defoliation, and plant death, but leaf necrosis, wilting, defoliation, and plant death, but often the most common symptom is stunting.often the most common symptom is stunting.

Root rot infections may be initiated from lesions on Root rot infections may be initiated from lesions on stems or from inoculum introduced to the potting mix stems or from inoculum introduced to the potting mix from debris surviving in the greenhouse. from debris surviving in the greenhouse.

Generally, moist but not wet conditions in the potting Generally, moist but not wet conditions in the potting mix favor development of Rhizoctonia crown and root mix favor development of Rhizoctonia crown and root rot on potted plants. rot on potted plants.

Spacing plants with a full canopy too close together can Spacing plants with a full canopy too close together can result in moisture and soil temperatures favorable for result in moisture and soil temperatures favorable for development of disease due to shading of the container development of disease due to shading of the container surface. surface.

Rhizoctonia crown and root rot.Rhizoctonia crown and root rot.

Rhizoctonia – Damping Rhizoctonia – Damping offoff

Rhizoctonia Crown Rot – Rhizoctonia Crown Rot – PoinsettiaPoinsettia

Rhizoctonia Blight – Rhizoctonia Blight – BegoniaBegonia

Rhizoctonia blight – Rhizoctonia blight – ImpatiensImpatiens

ControlControl Control of stem and root rot begins with thorough Control of stem and root rot begins with thorough

removal of all crop debris from the production removal of all crop debris from the production facility at the end of a cropping cycle.facility at the end of a cropping cycle.

Sanitation of work area and bench surfaces with Sanitation of work area and bench surfaces with surface disinfectants is important. surface disinfectants is important.

During propagation, misting cycles should be During propagation, misting cycles should be monitored closely to avoid over wetting foliage of monitored closely to avoid over wetting foliage of cuttings once newly made cuttings become turgid. cuttings once newly made cuttings become turgid.

In greenhouse production facilities with a history of In greenhouse production facilities with a history of Rhizoctonia stem and root rot, soaking dry rooting Rhizoctonia stem and root rot, soaking dry rooting strips in a fungicide solution can protect cuttings strips in a fungicide solution can protect cuttings from disease from disease

Generally one application of fungicide is sufficient to Generally one application of fungicide is sufficient to protect the crop during the propagation cycle. protect the crop during the propagation cycle.

After transplanting, fungicide drenches may be After transplanting, fungicide drenches may be needed at regular intervals to prevent crown and needed at regular intervals to prevent crown and root rotroot rot

Botrytis BlightBotrytis Blight

CAUSAL ORGANISM: CAUSAL ORGANISM: Botrytis cinereaBotrytis cinerea

Botrytis blight is common in all parts of Botrytis blight is common in all parts of the world. This fungus is not a specific the world. This fungus is not a specific pathogen and can take advantage of pathogen and can take advantage of many situations to produce a blight or many situations to produce a blight or rot condition on many hosts. rot condition on many hosts.

It is an opportunist on cut or pruned rose It is an opportunist on cut or pruned rose canes and will infect flowers and buds.canes and will infect flowers and buds.

Symptoms/SignsSymptoms/Signs

The most common symptoms usually are seen The most common symptoms usually are seen on young flower buds which droop, turn on young flower buds which droop, turn black at the base and later produce the black at the base and later produce the cottony grey-black mycelium of the fungus. cottony grey-black mycelium of the fungus.

Flowers can also be affected in the same way Flowers can also be affected in the same way and cut ends will have the black canker like and cut ends will have the black canker like symptoms with presence of mycelium. symptoms with presence of mycelium.

Cool and wet conditions facilitate grey-black Cool and wet conditions facilitate grey-black mycelial growth of Botrytis.mycelial growth of Botrytis.

Botrytis Stem Canker – Botrytis Stem Canker – Impatiens, PoinsettiaImpatiens, Poinsettia

Botrytis BlightBotrytis Blight

Botrytis Crown Rot - Botrytis Crown Rot - lisianthuslisianthus

Botrytis Blight – GeraniumBotrytis Blight – GeraniumResults from infected Results from infected

flowersflowers

Botrytis Dieback - Botrytis Dieback - GeraniumGeranium

Botrytis BlightBotrytis Blight

Disease CycleDisease Cycle This fungus is not specific and will grow on This fungus is not specific and will grow on

many different plants and plant debris. many different plants and plant debris. Under cool wet conditions profuse Under cool wet conditions profuse

sporulation results and spores are moved sporulation results and spores are moved to roses by air currents or blowing rain. to roses by air currents or blowing rain.

A minor wound in a bud or flower, or A minor wound in a bud or flower, or perhaps a pruning cut will provide the perhaps a pruning cut will provide the initial point of entry. initial point of entry.

As the infection progresses more As the infection progresses more sporulation results and additional sites sporulation results and additional sites become infected.become infected.

The fungus is a low level parasite and will The fungus is a low level parasite and will colonize wound sites as well as dead plant colonize wound sites as well as dead plant material.material.

ControlControl Prevention is the best means of control. This can be Prevention is the best means of control. This can be

accomplished through intense sanitation procedures. accomplished through intense sanitation procedures. By elimination of opportunistic colonization on dead By elimination of opportunistic colonization on dead

plant material the amount of sporulation can be plant material the amount of sporulation can be reduced. reduced.

Good ventilation is also essential in reducing disease Good ventilation is also essential in reducing disease incidence. Some sprays may give short term relief incidence. Some sprays may give short term relief but the fungus usually becomes quickly resistant. but the fungus usually becomes quickly resistant.

In greenhouse conditions special covers are used to In greenhouse conditions special covers are used to reduce the levels of ultraviolet light required by the reduce the levels of ultraviolet light required by the fungus for sporulation. fungus for sporulation.

In most cases, removal of infected plant parts and In most cases, removal of infected plant parts and protection of wounds by chemicals is all that can be protection of wounds by chemicals is all that can be done until warmer and dryer conditions prove too done until warmer and dryer conditions prove too unfavorable for continuing disease.unfavorable for continuing disease.

Black SpotBlack Spot

Caused by the fungus Caused by the fungus Diplocarpon Diplocarpon rosaerosae. The disease can cause almost . The disease can cause almost complete defoliation of bushes by complete defoliation of bushes by early fall.early fall.

It produces a weakened bush on It produces a weakened bush on which cane dieback, stem canker, which cane dieback, stem canker, and winter injury can become severe.and winter injury can become severe.

SymptomsSymptoms Circular black spots ranging from 1/16 inch to Circular black spots ranging from 1/16 inch to

1/2 inch in diameter appear generally on 1/2 inch in diameter appear generally on leaves’ upper sides. leaves’ upper sides.

The spots are frequently surrounded by a The spots are frequently surrounded by a yellow halo. Infected leaves characteristically yellow halo. Infected leaves characteristically turn yellow and fall prematurely. turn yellow and fall prematurely.

This leaf spot can be distinguished from This leaf spot can be distinguished from others by the fringed margin and consistently others by the fringed margin and consistently black color. black color.

Cane infection produces a reddish-purple Cane infection produces a reddish-purple spot. spot.

In many varieties, pale flower color is In many varieties, pale flower color is indirectly caused by infection.indirectly caused by infection.

Disease CycleDisease Cycle

Black spot is spread by splashing Black spot is spread by splashing water. Infection occurs after leaves water. Infection occurs after leaves are wet for several hours. are wet for several hours.

Therefore, the disease is more Therefore, the disease is more serious during periods of rainfall.serious during periods of rainfall.

ControlControl A preventive program for black spot should A preventive program for black spot should

begin with a thorough cleanup in the fall. begin with a thorough cleanup in the fall. Diseased leaves on the ground should be raked Diseased leaves on the ground should be raked and destroyed. and destroyed.

All diseased canes should be pruned off by All diseased canes should be pruned off by cutting several inches into good wood. cutting several inches into good wood.

A fungicide program should start in the summer A fungicide program should start in the summer just before leaves become spotted. From then just before leaves become spotted. From then until frost, the leaves may require a protective until frost, the leaves may require a protective fungicide coating. When the leaves are growing fungicide coating. When the leaves are growing rapidly or during rainy weather, it may be rapidly or during rainy weather, it may be necessary to spray the plants two times a week. necessary to spray the plants two times a week.

However, if growth is less rapid and rains are However, if growth is less rapid and rains are less frequent, spraying at 7 to 10 day intervals less frequent, spraying at 7 to 10 day intervals is usually sufficient is usually sufficient

Daylily RustDaylily Rust Daylily rust is caused by the fungus Daylily rust is caused by the fungus Puccinia Puccinia

hemerocallidishemerocallidis and affects the and affects the leavesleaves and and scapesscapes. .

It is not a new disease of daylilies,It is not a new disease of daylilies, havinghaving been been reported previously in China, Taiwan, Korea, Japan reported previously in China, Taiwan, Korea, Japan and Russia. and Russia.

Unfortunately, the disease has now arrived in North Unfortunately, the disease has now arrived in North America, and was first identified in the America, and was first identified in the southeastern United States in August 2000.  southeastern United States in August 2000.  Because of widespread shipping of infected plants, Because of widespread shipping of infected plants, by late 2001 daylily rust had been identified in by late 2001 daylily rust had been identified in approximately 30 US States, Canada and Australia.  approximately 30 US States, Canada and Australia.  In nature, however, the main method of rust spread In nature, however, the main method of rust spread is by wind borne spores is by wind borne spores

Daylily RustDaylily Rust

While daylily rust may kill the foliage on While daylily rust may kill the foliage on some cultivars, it is unlikely in the short some cultivars, it is unlikely in the short term to actually kill the infected plant. term to actually kill the infected plant. However, it is not yet known what the However, it is not yet known what the effects of continuous infection will be on effects of continuous infection will be on individual daylilies individual daylilies

SymptomsSymptoms

Symptoms and SignsSymptoms and Signs

Symptoms and SignsSymptoms and Signs

Disease CycleDisease Cycle

Disease CycleDisease Cycle It is not known where the rust overwinters. It is not known where the rust overwinters. It has successfully overwintered in some States of It has successfully overwintered in some States of

USDA Hardiness Zone 7 and milder as of April 2002 . USDA Hardiness Zone 7 and milder as of April 2002 . There are three possible ways that this rust may There are three possible ways that this rust may

survive the winter. survive the winter. The first is as urediospores, the orange powder The first is as urediospores, the orange powder

produced from the spots (known as pustules) on produced from the spots (known as pustules) on daylily leaves. daylily leaves.

Some rusts overwinter as mycelium (the strands Some rusts overwinter as mycelium (the strands which form the body of the fungus inside the leaf) which form the body of the fungus inside the leaf) but this can only take place where the plant tissue but this can only take place where the plant tissue remains alive.remains alive.

The third means by which rusts can overwinter is in The third means by which rusts can overwinter is in the form of teliospores. the form of teliospores.

Disease CycleDisease Cycle Teliospores are typically hardier and more durable Teliospores are typically hardier and more durable

than the urediospores and lie dormant on dead than the urediospores and lie dormant on dead daylily leaves over winter. daylily leaves over winter. These new spores must be transported by the wind or other These new spores must be transported by the wind or other

means to a plant of the alternate host, means to a plant of the alternate host, Patrinia,Patrinia, which is a which is a perennial plant also of Asian origin. Thus it is possible that in perennial plant also of Asian origin. Thus it is possible that in climates where the rust cannot survive the winter as climates where the rust cannot survive the winter as mycelium or urediospores, it may still be able to continue the mycelium or urediospores, it may still be able to continue the infection in the subsequent year if there is a plant of infection in the subsequent year if there is a plant of PatriniaPatrinia in the vicinity.in the vicinity.

PatriniaPatrinia is not common at the moment in North is not common at the moment in North America, but several species are being offered for America, but several species are being offered for sale both as plants and seeds. Not only does it pose sale both as plants and seeds. Not only does it pose a threat to daylilies as far as overwintering of the a threat to daylilies as far as overwintering of the rust is concerned, but the rust life cycle stage on rust is concerned, but the rust life cycle stage on Patrinia Patrinia is a form of sexual reproduction which may is a form of sexual reproduction which may increase the chances of new races of daylily rust increase the chances of new races of daylily rust developing.developing.

ControlControl

Cultivar selectionCultivar selection It is generally recommended to remove It is generally recommended to remove

the foliage from all plants discovered to the foliage from all plants discovered to have rust, cutting just above the soil level.have rust, cutting just above the soil level.

Fungicide applications mancozeb, Fungicide applications mancozeb, chlorothalonil, azoxystrobin and chlorothalonil, azoxystrobin and triadimefon triadimefon

Overhead watering should be avoided Overhead watering should be avoided wherever possible wherever possible