what is the disease or infection with my melon crop its color is turning into whitish. and dieing

can anyone please tell me what is happening with my crop?? my crop was quite healthy and happy. its age is 94days suddenly its color is turning into whitish and effecting plant to plant rapidly and dying fastly. so plz let me know whats the problem and how can i control or overcome this situation. not only my melon is effected but 90% of all melons arround my region every one is effected. and loosing hope.