Possible powdery mildew problem with pumpkins

Asked August 19, 2015, 9:47 PM EDT

I have pumpkin vines growing in my garden adjacent to tomato plants in a raised bed (6 feet by 8 feet by 2 feet high). The beds have very good quality soil with lots of compost. I have used zero pesticides. The pumpkin vines sprouted on their own from seeds left in my compost (which included last fall's Jack O'Lantern) and I decided to let the vines grow. They are now blossoming and have produced some small but growing pumpkins. The vines sprouted this May and have grown robustly up and out of my raised bed onto the adjacent lawn. They get plenty of sun. But now many leaves are developing a whitish film, which I suspect is powdery mildew. Based on the attached photos - which show this condition in different stages on different leaves - do you agree? To combat this problem I want to use only organic methods. Is it true that a diluted milk solution will cure this? How about potassium bicarbonate - and how is the latter supposed to be applied? Can you think of anything else? Thanks!!!

District of Columbia County District of Columbia

1 Response

Your photos show powdery mildew early and later stage. There are some reports that milk or potassium bicarbonate might have limited benefit, but we have data to support any specific recipe or formulation. http://www.extension.org/pages/30604/managing-cucurbit-powdery-mildew-organically#.VdXfjnFVhHw You could try any milk or potassium bicarbonate recipe that you can find online. vw