Question: query regarding dying of bitter gourd plant. 
Answer: --treatment: please do the bacterial test.
process: cut a piece of affected plant part, put into a glass of water and keep it for 30 minutes. if the the water will become yellowish white  than spray blitox 50 or blue copper 3gm per litter of water in the evening time. 

for insect attack management:  please spray azadirachtin 2ml/ litter or neem oil 5ml/litter or bacillus thuringiensis  2ml/litter of water in the evening time in the absence of rainfall.