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Pest & Disease Library · Solutions

Downy Mildew Control in Lettuce

Downy mildew is a moisture-driven disease that races through a crop in wet weather, defoliating plants from the leaves. This page covers downy mildew in lettuce.

Common crops affected

Why it matters

It spreads explosively when leaves stay wet, causing severe defoliation and yield loss; prevention ahead of wet weather is essential.

When it appears

Cool, wet, humid conditions and prolonged leaf wetness.

How to identify it

  • Pale yellow angular patches on the upper leaf surface
  • Fuzzy growth on the underside beneath the patches
  • Rapid spread in cool, wet weather

How to manage it

  1. Improve airflow; avoid overhead watering; water early.
  2. Remove infected leaves.
  3. Apply Spore Control (1:1,000) at first sign and ahead of wet weather.

Recommended Vegalab program

RoleProductUse
Primary controlSpore ControlThymol protective fungicide
CompanionMildew ControlWhere mildews dominate
Plant resilienceArmour BoostResilient tissue

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