Diseases of Vegetables - Lettuce

Downy Mildew.
Bremia lactuca

What to look for?
Common whole lettuce is grown usually in areas of cool, wet weather. Infected plants are unmarketable.

Photo: McDonald

Picture description
Mildew on undersides of leaves.

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Management strategy
Crop rotation should be practiced with an avoidance of land where the disease has previously occurred. Resistant cultivars are of little use.

Stunt.
Pythium spp.

What to look for?
Lettuce planted into cold, wet soil may stunt completely and die-off. In early stages, seedlings may die-off quickly but in older plants, die-off may be very slow and gradual.

Photo: Evans

Picture description
Pythium rotted root.

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Management strategy
Well drained warm soils should be used for early planting.

Photographs and information assembled and prepared for ARD by Dr. Ieaun R. Evans Agri-Trend Agrology Ltd.

Other Documents in the Series

Diseases of Vegetables
Diseases of Vegetables - Carrot
Diseases of Vegetables - Celery
Diseases of Vegetables - Corn
Diseases of Vegetables - Cucumber
Diseases of Vegetables - Garlic
Diseases of Vegetables - Lettuce - Current Document
Diseases of Vegetables - Muskmelon
Diseases of Vegetables - Onion
Diseases of Vegetables - Parsnip
Diseases of Vegetables - Pea
Diseases of Vegetables - Zucchini

For more information about the content of this document, contact Robert Spencer.
This information published to the web on November 26, 2003.
Last Reviewed/Revised on March 25, 2009.