Question: query regarding management of blight in pumpkin. 
Answer: pluck the excessively affected leaves from the plants and burn them in a separate place out from the field. spray copper oxychloride (blitox-50/ blue copper) 3 gram per liter of water 3 times at 5 days interval in the evening time in the absence of rain. if the insect is in control now the you can use neem oil 5ml/liter of water at 5 days interval.