Impatiens

Classic almost care free summer annual. Beautiful full clusters of flowers that butterflies and hummingbirds love.

Diseases of Impatiens October 30, 2008

       Diseases of Impatiens   

Disease Symptoms Pathogen/Cause Management
Alternaria Leaf Spot Target-like spots, often with purple or dark-colored borders form on the leaves. Alternaria spp. Reduce humidity and maintain good air circulation. Do not space plants too closely. Remove fading flowers and yellowing leaves. Apply iprodione, mancozeb, or triflumizole to protect plants. If plants are not flowering, chlorothalonil can be applied.
Botrytis Blight Flowers are spotted and stems rot. Botrytis cinerea Reduce humidity and maintain good air circulation. Do not space plants too closely. Remove fading flowers and yellowing leaves. Apply iprodione to protect plants. If plants are not flowering, chlorothalonil can be applied.
Bacterial Fasciation Plants are stunted and have many short shoots at the crown. Corynebacterium fascians Discard infected plants. Do not propagate from infected plants. Propagate and plant in pasteurized potting media.
Damping-Off Stems at the soil line die and plants collapse. Pythium or Rhizoctonia Plant in pasteurized potting media. Keep hose ends off the ground. Apply etridiazole + thiophanate methyl to protect plants.
Necrotic Spot Ring spots on leaves. Growing tips may die. Severe stunting. Impatiens necrotic spot virus Discard infected plants. Control thrips that carry the virus. Do not propagate from infected plants.
Powdery Mildew (New guinea impatiens) White, mealy fungal growth develops on the top of leaves. Sometimes, heavy gray growth develops.  Oidium Apply triflumizole to protect plants. If plants are not flowering, chlorothalonil can be applied.
Pythium Root Rot Lower leaves wilt, leaves fall and the plant dies. Pythium spp. Pot in pasteurized, pathogen-free media. Keep hose ends off the ground. Apply mefenoxam or fosetyl-Al to protect healthy plants.
Rhizoctonia Stem Rot Stems wilt and collapse.  Rhizoctonia Pot in pasteurized, pathogen-free media. Keep hose ends off the ground. Apply PCNB.
Thielaviopsis Root Rot Roots become dark brown and rot as microscopic spores form in the cells. Lower stems have sunken lesions when infected. Thielaviopsis basicola Pot in pasteurized, pathogen-free media. Keep hose ends off the ground. Apply etridiazole + thiophanate methyl or triflumizole to protect plants.
Verticillium Wilt Lower leaves yellow and fall. Infected plants may recover. Verticillium dahliae Pot in pasteurized, pathogen-free media. Do not take cuttings infected plants.

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