Causal Agent: 

Oomycete (Phytophthora infestans)

Characteristic Symptoms:
 
Lesions on the leaves are grayish green, large, irregularly shaped and water-soaked spots, which later on turn brown and increase in size.
   
When high moisture is present, white fungal growth develops with heavy sporulation on the underside of the leaf.
   
Fruit lesions are firm, large, irregular, brownish-green blotches and has a greasy, rough appearance.
   
During moist weather, blighting of entire plant could occur.
   
Crops Affected
 
Tomato, Potato
   
Management and Control:
 
Use disease-free seeds and seedlings.
   
Remove heavily infected tomato/potato plants from the field.
   
Avoid excessive moisture/prolonged leaf wetness.
   
Avoid excessive application of nitrogen.
   
Preventive application of systemic fungicides (metalaxyl, mancozeb, copper-based).
   
Preventive application of  fungicides such as cymoxanil+mancozeb (e.g. CurzateⓇ), cymoxanil famoxadone (e.g. Equation ProⓇ), chlorothalonil (e.g. Daconil®, Agronil®, Yoda®, Rover®, Yoda 500Ⓡ), Catan (e.g. Captan), difenoconazole+proficonazole (e.g. ArmureⓇ), propineb (e.g. Antracol), metalaxyl+mancozeb (e.g. Ridomil Gold MZ 68 WGⓇ, Apron XL 350 ESⓇ) and copper-based fungicides (e.g. Cupravit®, Super BlueⓇ, Vitigran blueⓇ, FunguranⓇ, KocideⓇ, Hydroxide superⓇ.
   
Apply protectant fungicides such as mancozeb (e.g. Attain M-80Ⓡ, Achem Mancozeb 80 WPⓇ, Micron 80 WOⓇ, VanzebⓇ) or chlorothalonil (e.g. Daconil®, Agronil®, Yoda®, Rover®, Yoda 500Ⓡ).

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