How to Manage Pests
Pests in Gardens and Landscapes
Phomopsis cane and leaf spot—Phomopsis viticola
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.
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.
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