Pea Powdery Mildew Treatment: Controlling Powdery Mildew In Peas

By Mary H. Dyer, Master Naturalist and Master Gardener

Powdery mildew is a common disease that afflicts many plants, and peas are no exception. Powdery mildew of peas can cause a variety of problems, including stunted or distorted growth, decreased harvest and small, flavorless peas. Read on for information on this pesky disease, along with tips on pea powdery mildew treatment.

Symptoms of Powdery Mildew of Peas

What causes powdery mildew in peas? Powdery mildew in peas often develops quickly when days are warm and dry, but nights are chilly with dewy mornings. Poorly drained soil and restricted air circulation also contribute to development of the disease.

The first sign of peas with powdery mildew is small, round, whitish or grey spots on the top of mature leaves. The powdery stuff is easy to rub off with your fingers.

Powdery mildew of peas spreads quickly and may cover entire leaves and stems, often causing the foliage to turn yellow or brown and die. This worsens the problem because peas without protection of leaves are more susceptible to sunburn. Eventually, affected leaves may develop small black spots, which are actually the spores.

Pea Powdery Mildew Treatment

Here are some tips for controlling powdery mildew in peas:

Plant peas where the plants receive early morning sunlight and avoid planting in shady spots. The sun will help dry dewy leaves and slow development of powdery mildew. Also, plant disease-resistant varieties whenever possible.

Avoid excess fertilization. When it comes to managing peas with powdery mildew, a slow-release fertilizer is often the best choice. Water peas early in the day so the plants have time to dry before temperatures drop in evening.

Some gardeners say that spraying plants weekly with a solution of baking soda and water at the first signs of disease may protect plants from further damage. If powdery mildew is mild to moderate, try spraying pea plants with a plant-based horticultural oil such as neem oil. Never spray when the temperature is above 90 F. (32 C.).

You can also spray peas with commercial fungicide at the first sign of the disease. If weather is conducive to powdery mildew, it helps to spray the leaves even before the disease shows up. Biological fungicides, which are safe for pets, people and beneficial insects, may be useful but generally aren’t as powerful against mildew as chemical fungicides. Keep in mind that fungicides are of little use once the disease is established.

Remove and destroy badly infected pea plants to prevent further spreading. Clean beds thoroughly in fall; powdery mildew spores overwinter in plant debris.

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