How to Manage Pests

Pests in Gardens and Landscapes

Phomopsis cane and leaf spot—Phomopsis viticola

Identification

Leaf blades and veins infected with Phomopsis have tiny dark to brown spots with yellowish margins; basal leaves may become distorted. On shoots, small spots with black centers are found. Berries may have light brown to dark spots on them and eventually shrivel and become mummified. Infected canes appear bleached during the dormant season. Severely affected canes or spurs exhibit an irregular dark brown to black discoloration intermixed with whitish bleached areas.

Life cycle

Infection generally occurs in spring when shoots begin to grow. Around budbreak, spores released from overwintering structures on diseased canes, spurs, and bark are splashed by rain onto newly developing shoots. Infection occurs when free moisture remains on the unprotected green tissues for many hours. Heavy and prolonged rains in late March and April, soon after budbreak, are ideal for spring infection.

Solutions

Phomopsis cane and leaf spot is most serious following a wet spring. However, it is not a serious concern in home vineyards. Prune out bleached canes during the dormant season.

Leaf spots with yellowish margins
Leaf spots with yellowish margins

Infected cane
Infected cane

Scabby shoots
Scabby shoots


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