Pathogens CoveredPathogens Covered

PythiumPythium spp. spp. PhytophthoraPhytophthora spp. spp. FusariumFusarium solani solani RhizoctoniaRhizoctonia solani solani

Black Leg of GeraniumBlack Leg of GeraniumPythiumPythium spp. spp.

Pythium Root Rot of Pythium Root Rot of Impatiens Impatiens

Control:Control:

Take special care during transplanting Take special care during transplanting to avoid excessive planting depth and to avoid excessive planting depth and wounding of stem and root tissue. wounding of stem and root tissue.

Avoid excessive soil compaction during Avoid excessive soil compaction during the transplant operation. the transplant operation.

Water carefully; avoid overwatering. Water carefully; avoid overwatering. Drench-applied fungicides can be Drench-applied fungicides can be

effective in controlling this disease effective in controlling this disease problem.problem.

Phytophthora Damping Phytophthora Damping OffOff

Phytophthora root rotPhytophthora root rot

Phytophthora root rot is caused by several Phytophthora root rot is caused by several species of fungi in the genus species of fungi in the genus Phytophthora. Phytophthora.

Phytophthora cinnamomiPhytophthora cinnamomi is usually credited is usually credited with causing the greatest damage to container- with causing the greatest damage to container- and field-grown woody ornamentals. and field-grown woody ornamentals.

P. parasitica, P. citricola,P. parasitica, P. citricola, and possibly and possibly P. P. cactorum,cactorum, are also known to attack woody are also known to attack woody plants, particularly azaleas and rhododendrons. plants, particularly azaleas and rhododendrons.

Phytophthora cryptogeaPhytophthora cryptogea has been known to has been known to cause heavy damage on junipers in poorly cause heavy damage on junipers in poorly drained landscape bedsdrained landscape beds

Phytophthora Root RotPhytophthora Root Rot Symptoms: Symptoms:

Phytophthora root rot greatly reduces the volume of the Phytophthora root rot greatly reduces the volume of the roots which are needed by the plant to absorb water roots which are needed by the plant to absorb water and nutrients. and nutrients.

The roots on diseased plants are brittle and brown to The roots on diseased plants are brittle and brown to reddish-brown in color. reddish-brown in color.

A network of fine, discolored feeder roots may be A network of fine, discolored feeder roots may be confined to one area or include the entire root system. confined to one area or include the entire root system. The fungus usually colonize the crown of the plants, The fungus usually colonize the crown of the plants, often girdling the stem at or just above the soil line. A often girdling the stem at or just above the soil line. A brown to reddish-brown discoloration of the tissues brown to reddish-brown discoloration of the tissues occurs just below the bark and may extend up the stem occurs just below the bark and may extend up the stem above the soil line.above the soil line.

On some trees and large shrubs--such as dogwood--On some trees and large shrubs--such as dogwood--brown, water-soaked cankers oozing a dark-colored fluid brown, water-soaked cankers oozing a dark-colored fluid or gum may develop at the soil line.or gum may develop at the soil line.

Phytophthora Root RotPhytophthora Root Rot Symptoms: Symptoms:

Phytophthora Root RotPhytophthora Root Rot Symptoms: Symptoms:

These symptoms can easily be confused with These symptoms can easily be confused with those of a nutritional disorder, overwatering, those of a nutritional disorder, overwatering, drought stress, and a number of other factors drought stress, and a number of other factors and so can be overlooked by the grower. and so can be overlooked by the grower.

Slight yellowing of the leaves followed quickly by Slight yellowing of the leaves followed quickly by permanent wilting and plant death are the permanent wilting and plant death are the symptoms usually associated with Phytophthora symptoms usually associated with Phytophthora root rot on container-grown azaleas and root rot on container-grown azaleas and rhododendronsrhododendrons

In landscapes, established plants may show In landscapes, established plants may show symptoms of general decline for one or more symptoms of general decline for one or more years before succumbing to root rot, while newly years before succumbing to root rot, while newly planted azaleas will quickly die.planted azaleas will quickly die.

Phytophthora Root RotPhytophthora Root Rot Symptoms: Symptoms:

Symptoms vary according to the degree of root Symptoms vary according to the degree of root colonization by Phytophthora root rot fungi, plant colonization by Phytophthora root rot fungi, plant age, plant susceptibility to root rot, and age, plant susceptibility to root rot, and environmental stress. environmental stress.

Typically, symptoms first appear on one plant and Typically, symptoms first appear on one plant and later on surrounding plants in both container areas later on surrounding plants in both container areas and landscape beds. Some yellowing of the foliage, and landscape beds. Some yellowing of the foliage, particularly at the shoot tips, leaf shed, slowed particularly at the shoot tips, leaf shed, slowed plant growth, and possibly limb dieback may occur plant growth, and possibly limb dieback may occur in early stages of the disease in early stages of the disease

However, it is not uncommon for liners or container-However, it is not uncommon for liners or container-grown plants to remain almost symptomless until grown plants to remain almost symptomless until after transplanting into larger containers or after transplanting into larger containers or landscape beds. landscape beds.

Phytophthora Root Rot of Phytophthora Root Rot of GardeniaGardenia

Phytophthora Phytophthora Symptoms: Symptoms:

The foliage of azaleas and rhododendrons may The foliage of azaleas and rhododendrons may also be invaded by some Phytophthora root rot also be invaded by some Phytophthora root rot fungi. fungi.

Irregular blotches which are first olive-colored Irregular blotches which are first olive-colored and later brown, sometimes with a red margin, and later brown, sometimes with a red margin, develop on the leaves. develop on the leaves.

Diseased leaves are usually shed by the plant. Diseased leaves are usually shed by the plant. Damage usually appears on limbs near the Damage usually appears on limbs near the

base of the plant.base of the plant.

Phytophthora Crown Rot – Phytophthora Crown Rot – Holiday CactusHoliday Cactus

Phytophthora Crown Rot / Phytophthora Crown Rot / PoinsettiaPoinsettia

Phytophthora / PoinsettiaPhytophthora / Poinsettia

Disease CycleDisease Cycle PhytophthoraPhytophthora spp. survive as resting structures spp. survive as resting structures

(chlamydospores and oospores) and mycelia in (chlamydospores and oospores) and mycelia in diseased roots, crowns, and other crop debris. diseased roots, crowns, and other crop debris.

The resting structures are released into the soil The resting structures are released into the soil or potting media from infested crop debris and or potting media from infested crop debris and are readily spread from pot to pot throughout are readily spread from pot to pot throughout propagation and container production areas by propagation and container production areas by soil and splashing or flowing water. soil and splashing or flowing water.

Recycled irrigation and runoff water has been Recycled irrigation and runoff water has been implicated as a source of these fungi in implicated as a source of these fungi in rhododendron nurseries. rhododendron nurseries.

Disease CycleDisease Cycle Heaviest losses to root rot in most container Heaviest losses to root rot in most container

production nurseries usually occur on flat, production nurseries usually occur on flat, poorly drained beds where water is allowed to poorly drained beds where water is allowed to stand around container bases stand around container bases

Overwatering in the nursery or landscape will Overwatering in the nursery or landscape will also contribute to losses from the disease. also contribute to losses from the disease.

Phytophthora root rot is most commonly seen Phytophthora root rot is most commonly seen in field production nurseries and landscape in field production nurseries and landscape plantings on poorly drained, waterlogged soils plantings on poorly drained, waterlogged soils that are prone to flood. Disease development that are prone to flood. Disease development is usually slow or absent on well-drained sites.is usually slow or absent on well-drained sites.

Control:Control: Prevention is the key to controlling Phytophthora Prevention is the key to controlling Phytophthora

root rot in commercial nursery stock. Once root rot in commercial nursery stock. Once symptoms start to appear, much of the damage symptoms start to appear, much of the damage has already been done. has already been done.

No single control measure will ensure protection No single control measure will ensure protection from from PhytophthoraPhytophthora. .

Several approaches must be directed at Several approaches must be directed at preventing the introduction and spread of these preventing the introduction and spread of these fungi and at preventing conditions favorable for fungi and at preventing conditions favorable for disease development. disease development.

These approaches include proper establishment These approaches include proper establishment and production practices, disease resistance and and production practices, disease resistance and chemical controlchemical control

Caused by Caused by Fusarium solaniFusarium solani Infection takes place at the soil lineInfection takes place at the soil line This is followed by the production of This is followed by the production of

a brown spot. a brown spot. As the tissue dies, it becomes tan As the tissue dies, it becomes tan

and falls away, removing tissue from and falls away, removing tissue from the edge to the heavy center vein the edge to the heavy center vein tissue tissue

Fusarium Stem Rot - Fusarium Stem Rot - DieffenbachiaDieffenbachia

Fusarium Stem Rot - Fusarium Stem Rot - DieffenbachiaDieffenbachia

Caused by Caused by Fusarium solaniFusarium solani Infection takes place in the rootsInfection takes place in the roots Lower leaves turn yellow and wilt, followed Lower leaves turn yellow and wilt, followed

by overall plant wilting and death of entire by overall plant wilting and death of entire plant. Lower portion of stem near soil line plant. Lower portion of stem near soil line turns dark brown-to-black with brown turns dark brown-to-black with brown discoloration in vascular tissues. discoloration in vascular tissues.

Fusarium WiltFusarium Wilt

Fusarium Wilt -Fusarium Wilt -ChrysanthemumChrysanthemum

Fusarium Wilt -Fusarium Wilt -ChrysanthemumChrysanthemum

Fusarium Wilt -Tip Necrosis Fusarium Wilt -Tip Necrosis of lisianthusof lisianthus

Fusarium Wilt -Tip Necrosis Fusarium Wilt -Tip Necrosis of lisianthusof lisianthus

ManagementManagement

Planting disease-free cuttings, Planting disease-free cuttings, sterilization of potting soil and sterilization of potting soil and benches offer best means of control.benches offer best means of control.

Do not injure plants at the soil line. Do not injure plants at the soil line. Apply iprodione Apply iprodione (Kidon, Rovral, Chipco 26019)(Kidon, Rovral, Chipco 26019)

or etridiazole or etridiazole (Truban, Terrazole)(Truban, Terrazole) + + Thiophanate-methyl Thiophanate-methyl (Banrot)(Banrot) to protect to protect healthy plants.healthy plants.

Anthracnose and brown Anthracnose and brown leaf spotleaf spot

Caused by (Caused by (Colletotrichum spp.Colletotrichum spp. or or Leptosphaeria spp.Leptosphaeria spp.) )

Occur throughout the world in Occur throughout the world in greenhouse and indoor landscapes.greenhouse and indoor landscapes.

Symptoms/SignsSymptoms/Signs

• Symptoms of two leaf spots are very similar, Symptoms of two leaf spots are very similar, with both occurring primarily during the with both occurring primarily during the cooler, winter months. cooler, winter months.

• Leaf spots are initially tan and water-soaked Leaf spots are initially tan and water-soaked and may have a bright yellow halo. and may have a bright yellow halo.

• Fruiting bodies of the causal organism Fruiting bodies of the causal organism ((GlomerellaGlomerella or or ColletotrichumColletotrichum spp. spp. [anthracnose]) or [anthracnose]) or LeptosphaeriaLeptosphaeria sp. (brown sp. (brown leaf spot) appear in concentric rings of tiny leaf spot) appear in concentric rings of tiny black specks within the leaf spot. black specks within the leaf spot.

Colletotrichum - Colletotrichum - DieffenbachiaDieffenbachia

Colletotrichum - Colletotrichum - cyclamencyclamen

Colletotrichum -cyclamenColletotrichum -cyclamen

Control - Control -

Keep foliage dry, and protect from cold Keep foliage dry, and protect from cold water drips due to condensation on water drips due to condensation on overhead structures. overhead structures.