How to Detect and Prevent Powdery Mildew

By eHow Home & Garden Editor

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Powdery mildew attacks flowering annuals. This fungus thrives with heavy rainfall and high humidity, but is also caused by temperature changes between day and night. Foliage suffering from powdery mildew looks like it has a white coating of talcum powder.

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Instructions

Difficulty: Moderate

Things You’ll Need:

Spray Bottles
Garden Hoses
Gardening Gloves
Horticultural Oils
Leaf Rakes
Shovels
Baking Soda
Sulfur Powder

Step1

Look for a grayish-white powder on leaves. Plants affected by this disease include roses, zinnia, zucchini and verbena.

Step2

Avoid overhead irrigation if possible. If there are sprinklers near the affected plants, either cap them or move the plants to a drier location.

Step3

Water in the early morning hours so that plants have a chance to dry during the day. When watering plants, avoid wetting leaves. Hold the hose near the base of the plant instead of watering from overhead.

Step4

Protect plants from heavy rainfall. Place susceptible plants under overhangs or eaves.

Step5

Clean your garden of any infected plants, especially in winter, for maximum protection against the disease. Dispose of infested plants and don't compost them.

Step6

Keep the area under mildew-prone plants raked and clean. Fungus spores splash back onto the foliage during rainfall or irrigation.

Step7

Spray with a solution of 1 tsp. baking soda and 1/2 tsp. horticultural oil mixed with 1 qt. of warm water in a 1-qt. sprayer. Don't forget to spray the undersides of leaves.

Step8

Spray or dust plants with sulfur-based fungicides as a last resort.

Tips & Warnings

Plant mildew-resistant varieties of plants. Waxy-leaved plants, including bird of paradise, canna and aspidistra, are usually resistant to powdery mildew.
Although powdery mildew looks horrible, it causes little harm to the plant. Harvest your zucchini and enjoy the fruits of your labor.
Always use the least toxic method of control as your first step.
Fungicides are among the most toxic garden chemicals. Wear goggles, neoprene gloves, a respirator, and long sleeves and pants when applying them.