Powdery mildew is one of the most common issues gardeners see in zucchini plants. Signs of Powdery Mildew It starts as white patches on the leaves of squash, lilacs, phlox, bee balm, and other plants, making them look like they have been dusted with baby powder. My zucchini plants got powdery mildew this year and I got rid of the mildew! The mildew forms spores that spread through wind, insects, and water run-off, which carries the disease to … Powdery Mildew Cycle. Take note that downy mildew isn’t as powdery in appearance, either. Step 2. Preventing Powdery Mildew. However, downy mildew appears only on the bottom (or underside) of the leaf. Thankfully, it's fairly easy to prevent and treat, if … Early on it wipes off or washes away only to return again. Step 3. The first evidence of powdery mildew on a zucchini plant is whitish-gray … Some people say that the ladybirds that feed on this mildew spread it by carrying spores, others … Potassium bicarbonate – Similar to baking soda, this has the unique advantage of actually eliminating powdery mildew once it’s there. In contrast, powdery mildew will appear anywhere on the leaf. Spray on plants every one to two weeks. Powdery mildew is a fungal disease caused by the many varieties of the fungi that belong to the order Erysiphales. Then sprayed each infected leaf each morning until the spots when away. Eventually the affected leaves turn yellow and die on many plants while others continue to soldier on. As directed by my mother, I combined a tsp of baking soda with a quart of water in a spray bottle; shook it up real good so all the soda dissolved. Potassium bicarbonate is a contact fungicide which kills the powdery mildew spores quickly. Powdery mildew is sometimes confused with the similar downy mildew. Mix 1 cup of skim milk with 9 cups of water. Step 1. Pour the mixture into a garden sprayer. Homemade Remedy for White Powdery Mildew on Zucchini. The fungus thrives in warm, humid environments, and overwinters in the soil. If untreated, the small white spots will grow, forming a root-like structure. Step 4. It's an opportunistic fungal disease that saps nutrients from the leaves and stems of your plants, and may spread to infect other areas of your garden. In addition, it’s approved for use in …