Search Articles

Downy Mildew

Irregular brown or yellow spots on leaves are an early symptom of this fungal disease, which can infect many vegetable crops. Check the undersides of affected leaves; presence of a hairy white or purple mold confirms the diagnosis. Severely infected leaves may die, and the disease can eventually spread to stems, flowers, and fruit.

The fungus overwinters on plant debris. Downy mildew is a host-specific disease. Thus, if your cucumber plants become infected, that doesn’t necessarily mean your onions will succumb.

Prevention and Control
  • Grow mildew-resistant varieties such as Fanfare cucumber and Allstar melon. Late-season crops tend to be more vulnerable to downy mildew.
  • Plant disease-free seeds and plants.
  • Space plants widely to promote good air circulation. This will help leaf surfaces stay dry, which inhibits infection.
  • Keep foliage as dry as possible by using drip irrigation or soaker hoses rather than overhead watering.
  • Control weeds, such as wild mustard, that can harbor the disease.

Share This Article

Sign Up for E-mail

Get the latest news, tips and gardening info!

Sign Up
Looking for Product Instructions?

Assembly instructions, diagrams and other types of product information are available on product pages. To find it, search for the product, go to the product page and click on the "How-To and Instructions" tab.

We're a B Corp!

Gardener's Supply is pleased to be part of a class of companies called B Corps. With this certification comes a dual mission that combines bottom-line success and social responsibility. In short: Do well and do good.

Learn More

Learn and Share

Our website is packed with how-tos and inspiration, as well as opportunities to share with fellow gardeners. Check back often to view new articles, videos, blog posts and Facebook updates and join our online community.

Learn & Share

Satisfaction Guaranteed

We stand by the quality of our products and our service. If for any reason you're not satisfied with your purchase, you can return it to us for an exchange, refund, or credit.

Learn More