Causal Agent: 

Fungi (Phoma cucurbitacearum; Didymella bryoniae)

Characteristic Symptoms:
 
Leaf spots, mostly on leaf edges are light brown and expand to the center of the leaf usually forming a V- or U-shape lesion.
   
Stem lesions are light brown and often elongated and can be found at or near the stem base usually resulting from an expansion of a leaf infection.
   
Older leaves can become yellowish and die when the first fruit sets.
   
Fruit infection usually starts from the blossom end.
   
Conditions for Disease Development:
 
The pathogen survives between seasons on diseased vines and crop debris and may be seed-borne.
   
Moisture/high relative humidity is more important for disease development than temperature.
   
Cotyledons and young leaves of pumpkin are resistant but become susceptible as they mature.
   
The time between infection and symptom appearance is 3-7 days, in which large number of spores/conidia are produced.
   
Free moisture on leaves for 1 hr is necessary for infection and further continuous leaf wetness is required for lesion expansion.
   
Spores are disseminated by rain splashes or irrigation water.
   
Management and Control:
 
Use resistant varieties, if available.
   
Use pathogen-free seed.
   
Avoid prolonged moisture to minimize severity.
   
Remove and destroy heavily infected leaves to minimize spread.
   
Crop rotation for 2 years can help reduce inoculum in the soil.
   
Spray/drench with chemical fungicides such as carbendazim ( (Bavistin 50 DFⓇ, Goldazim 500 SSⓇ, Minx 500 SCⓇ, SuperdazimⓇ, Avert 50 WPⓇ, BiostinⓇ), difenoconazole (e.g. ScoreⓇ, MontanaⓇ, PursueⓇ, BashⓇ), Difenoconazole+proficonazole (e.g. ArmureⓇ), Pyraclostrobin (e.g. Cabrio 25 ECⓇ) and metalaxyl+mancozeb (e.g. Ridomil Gold MZ 68 WGⓇ, Apron XL 350 ESⓇ) as early as symptoms are observed. 
   
References:
compendium of Cucurbit Diseases (1996) by the American Phytopathological Society; Management of GSB (http://edis.ifas.ufl.edu/pdffiles/PP/PP28000.pdf)
   

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