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Powdery Mildew

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Powdery Mildew

A powdery white growth on leaves is the first evidence of this fungal disease, which affects beans, cucumbers, squash, pumpkins, lettuce, peas and many other kinds of plants. The fungus can spread to flowers and fruit. New growth and succulent plant tissues are particularly vulnerable to infection. Infected areas eventually turn yellow and dry up; severe infection can weaken or even kill entire plants.

Unlike other fungal diseases, powdery mildew does not require wet foliage for infection to occur, although it does require high humidity. It can spread quickly in warm, dry climates. The fungus overwinters on plant debris.

Prevention and Control
  • Plant powdery mildew-resistant varieties, such as Super Sugar Snap pea.
  • Water plants as needed to prevent moisture stress.
  • Keep plants well spaced and weeded to optimize air flow around the leaves.
  • Avoid excess nitrogen fertilizer, especially late in the growing season.

Recommended Products

  • Garden Dust Contains copper sulphate and pyrethrins. Use it as a last resort if other controls are not effective
  • Bon-Neem Spray Controls a variety of pests, including aphids, mites, whiteflies, flea beetles, scale and earwigs. Contains natural potassium salts and potent neem tree oil.
  • Serenade® Garden Disease Control Works with Bacillus subtilis, a soil-dwelling bacterium that controls anthracnose, bacterial spot, leaf blight, early and late blights, rust, powdery mildew, gray mold and black mold, scab and many other diseases.
  • Actinovate® Contains a patented beneficial microbe that helps control a wide range of diseases.
  • Orchard Spray Protects fruit trees and bushes, nut trees, ornamentals and vegetables. Effective against blight, blackspot, powdery mildew, aphids, mites, caterpillars, whiteflies and more plant pests and diseases. Active ingredients: sulphur and pyrethrins
  • Rose Rx 3-in-1 Wards off spider mites, whiteflies, lily beetles and Japanese beetles. Also controls black spot and powdery mildew. It works for all flowers and ornamentals; safe for houseplants and food crops, too.

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