Downy Mildew of Lettuce

Bremia lactucae

Description:

A fungal disease that shows mainly on the top side of oldest leaves as pale yellow approximately diamond shaped lesions bounded by veins. These go brown with time and furry white hyphal growth may develop on the under side opposite the lesions. Bacterial soft rots then set in to turn the leaf slimy.

Species Affected:

Lettuce.

Biology:

Spores are spread by wind.

Life Cycle:

Origin and History:

Distribution:

Significance:

Management and Control:

Destroy all infected crop residues and surplus leaves.
Decrease planting density
Rotate with resistant crops.
Apply fungicides at the first sign of disease.

Related and Similar Species:

References:

1291

Acknowledgments:

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