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.

COMMON NAME	TRADE NAME
chlorothalonil	Daconil, Exotherm Termil
etridiazole	Terrazole, Truban
etridiazole + thiophanate methyl	Banrot
fosetyl-Al	Aliette
iprodione	Chipco 26019
mefenoxam	Subdue Maxx
metalaxyl	Subdue
PCNB	Terraclor
propamocarb	Banol
thiophanate methyl + mancozeb	Zyban
triflumizole	Terraguard