Plant guide:ðŸĨ’ Cucumber
Back to Plant Clinic
⚠ Critical
ðŸĐš
Fungal

Downy Mildew on Cucumber Leaves

Commonly affects: Cucumis sativus (Cucumber)

Angular yellow patches bounded by leaf veins appear on the upper surface, with grey-purple fuzzy growth on the underside, spreading rapidly in humid weather.

Potential Causes

  1. 1Pseudoperonospora cubensis, an airborne water mould spreading long distances on wind
  2. 2Extended leaf wetness from rain or overhead irrigation
  3. 3Cool nights combined with warm, humid days

Solution Steps

  1. 1Remove and destroy affected leaves promptly
  2. 2Water at the base only, avoiding overhead irrigation
  3. 3Apply a copper-based fungicide preventively if downy mildew is active regionally
  4. 4Improve airflow between plants

Prevention Tip

Downy mildew spreads from regional outbreaks on wind currents — act quickly at the first sign since it can defoliate a planting within days.

More Fungal & Bacterial Disease Problems

See all →
Powdery Mildew — Erysiphe & Golovinomyces spp. — anthurium plant care

Powdery Mildew — Erysiphe & Golovinomyces spp.

Bacterial & Fungal Leaf Spot — Xanthomonas & Cercospora spp. — calathea plant care

Bacterial & Fungal Leaf Spot — Xanthomonas & Cercospora spp.

Anthracnose — Colletotrichum Leaf Blight — monstera plant care

Anthracnose — Colletotrichum Leaf Blight

Fusarium Wilt — Vascular Browning & Collapse — monstera plant care

Fusarium Wilt — Vascular Browning & Collapse

See how growers dealt with this →
Track this problem in your grow diary