How to Treat Powdery Mildew Using Organic Methods
To successfully kill powdery mildew on pumpkin leaves, act at the earliest signs of infection. There are many approved organic treatments for white fungus, but the one with the greatest reported success also happens to be the simplest: a solution of milk and water, sprayed on the leaves.
Here's how to make your own milk solution to treat powdery mildew on pumpkins.
Milk Solution to Treat Powdery Mildew
In a spray bottle, mix:
1 part milk (whole, 2%, or skim milk will all kill the fungus)
1 part tap water
Treat your pumpkin plants at dusk only — wetting plants during the day can result in leaves getting baked by the hot sun.
Spray both the top and the undersides of the leaves, as both are affected by the powdery mildew.
Spray pumpkins infected with powdery mildew every 3 to 4 days until the white fungus is gone. You may also spray uninfected pumpkins with the milk and water solution every 7 to 10 days as a preventative measure.
The milk spray is the best treatment for powdery mildew, but other organic methods you may try are sulfur-based fungicides, available commercially, and a baking soda solution. The baking soda spray is 1 teaspoon baking soda to 1 quart of water, plus a few drops of liquid dish soap. The soap acts as "glue," allowing the baking soda to adhere to the leaf.