Powdery Mildew on a Zucchini Plant

A healthy zucchini plant should be free from powdery mildew.

Foliage diseases, such as powdery mildew and downy mildew, plague zucchini plants around the world. Powdery mildew is a fungal infection caused by an airborne spore. It is most severe in hot, humid areas.

Identification

Plants affected by powdery mildew will develop white spots on their upper and lower leaves that look like talcum powder. The affected leaves will eventually wilt and turn yellowish. The infection can also spread to the blossoms and the fruit.

Prevention/Solution

The most common and least expensive preventative treatment is to make a solution of 1 percent baking soda and 1 percent horticultural oil, which encourages the baking soda to stick to plant leaves, in water. Spray the solution on the plant every two weeks.

Treating Powdery Mildew

If you do get powdery mildew, cut off any affected leaves and burn them. Spray the plant with one of three treatments: a commercial fungicide, a solution of 10 percent garlic and 90 percent water, or a mixture of equal parts milk and water.

References

• Colorado State University Extension: Powdery Mildews
• The National Sustainable Agriculture Information Service: Use of Baking Soda as a Fungicide
• TheFrugalLife.com: Got Powdery Mildew? Get Milk!
• Hydroponics-at-Home.com: Powdery Mildew