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Powdery mildew

Causal organism: Fungus

Important species
  • Powdery mildew of tomato, pepper, eggplant, potato and other solanacoeus crops, squash, cucumber and other cucurbits (Erysiphe orontii)
  • Powdery mildew of carrot (E. polygoni)
  • Powdery mildew of cucurbits (E. cichoracearum; Sphaerotheca fuliginea, Podosphaera fusca; P. fuliginea)
  • Host plants

    Cereals, grasses, vegetables, ornamentals, weeds, shrubs, fruit trees, and forest trees

    Affected plant stages

    Seeding, vegetative, and reproductive stages

    Affected plant parts

    Leaves, petioles, stems, and sometimes, fruits


    picture discription
    Photo courtesy of Andy Wyenandt
    The Ohio State University

    Powdery mildew is characterized by a dusty-white to gray coating and talcum powder-like growth commonly infecting plant's leaves. It begins as circular, powdery-white spots that turn yellow-brown and finally black. In most cases, the fungal growth can be partially removed by rubbing the leaves.

    Powdery mildew is commonly found on the upper side of the leaf. It also infects the underneath surface of the leaf, young stem, bud, flower, and young fruit. The infected leaf becomes distorted, turns yellow with small patches of green, and falls off prematurely. Infected buds fail to open. Other injuries include stunting and distortion of leaves, buds, growing tips, and fruits. Infected seedlings will eventually die.

    Conditions that favor development

    1. Warm and dry climate with high humidity
    2. Infected seeds and planting materials
    3. Overcrowded plants

    Prevention and control

    1. Plant resistant cultivars when available
    2. Practice a wider spacing between the hills and the rows to increase air flow among plants, and light penetration
    3. Practice crop rotation
    4. Remove infected plant materials and alternative hosts
    5. Prune overcrowded plants to increase air circulation, reduce the relative humidity, reduce infection, and increase the light penetration
    6. Plow under all plant residues or remove plant residues after harvest. Do not place infected plant materials on the compost pile
    7. Ginger powder extract
    8. Neem seed extract
    9. Papaya extract
    10. Turmeric extract
    11. Baking soda
    12. Bordeaux mix
    13. Seed treatment
    14. Compost tea

    External links


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