For the last couple of seasons, I've been using a solution of milk and water to treat powdery mildew on my squash, zucchini, cucumbers and mellons. Here is Jacksonville Beach, FL, the cucurbits seem to very vulnerable to powdery mildew. We have seen powdery mildew on some of our cucurbits every season. We try to raise and maintain our gardens without using chemicals, so I sought out a more natural way to fight the powdery mildew. I stumbled upon some research that shows a milk solution is effective for fighting powdery mildew. I use a generic 32oz spray bottle (pictured above) to apply the milk solution. I add 1/4 cup of milk to the bottle then fill with water. I usually spray all the squash if any of them are infected. I try to wet the leaves on the top and bottom.
My experience has been, that if i catch the powdery mildew early, when the plants are still healthy but are showing white spots, treating them for 3 or 4 days in a row, usually clears up the mildew. When I start treating plants with milk after some of the leaves have withered and others leaves are yellowing or brown, the plants are less likely to survive, but some do. Early treatment, consistent over 3 or 4 days, seems to be the best solution for treating the powdery mildew.
It seems that we have had a powdery mildew infection on our squash and zucchini plants every spring for the past 5 years. Since I wrote this article last year about measures to take to prevent powder mildew , we have been powdery mildew free! In reallity we were probably helped out this year by the weather, as well as our preventive measures. We followed most of the guidelines already, but I wanted to share a couple of things that seem to make the biggest difference from my experience.
Here in Florida our sub-tropical (seems to be getting more tropical every year) climate makes a nice environment for many fungal infections. Hot temperatures and high humidity combined with nice green cucurbits like zucchini, squash, pumpkins, and gourds, make a very inviting environment for podwery mildew. The spores travel on the wind, and when they land in such an ideal spot, they try to set up camp. I believe that cucurbits have some natural resistance to fungal infections, but if the fungus gets even a slight advantage, it will win in the end.
Powdery mildew is a fungal disease which affects many types of plants. Cucurbits like zucchini, squash, pumpkins, melons and gourds are all succeptable to powdery mildew. It usually appears on leaves as small round white powdery spots which quickly spread and cover the entire leaf. In our garden here at the yardstead we've lost many zucchini, squash and pumpkin plants to powdery mildew. This year powdery mildew killed all of our zucchini and most of our paty pan sqash and yellow squash.
It is usually easy to identify powdery mildew by its appearance on the top of the leaves. It usually looks like white powder on the leaves. Infected leaves usually turn yellow and wilt after just a few days. Powdery mildew usually appears in our garden on one or two plants then quickly spreads to all the other zucchini and squash plants. The infected plants usually don't die completely and frequently send out new leaves and flowers. We have been able to recover from powdery mildew in the garden a few times, when we caught it early and sprayed all the plants with neem oil.
On a few other occasions I applied the funigicide ...........