How to Manage Pests

Pests in Gardens and Landscapes

Downy mildew—Plasmopara viticola

Downy mildew causes yellowish and oily or angular, yellow to reddish and brown lesions on leaves. Lesions are limited by the veins. Sporulation of the fungus appears as dense, white, cottony growth in the lesions. Infected shoot tips and petioles thicken and curl and eventually turn brown and die. Young berries appear grayish.

Life cycle

Solutions

The best way to control downy mildew is by prevention. Preventative management consists of effective soil drainage and reduction of sources of overwintering inoculum, such as pruning out the infected ends of shoots. Extend the interval between sprinkler irrigations as long as possible.

Downy mildew lesions on grape leaves
Downy mildew lesions on grape leaves

Statewide IPM Program, Agriculture and Natural Resources, University of California
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