Phomopsis cane and leaf spot
Infected leaves have small, yellowish spots with dark brown centers and may be puckered. On petioles, shoots and rachises, elongated black spots or streaks develop that make the tissue brittle.
Most shoot lesions occur on the basal three to six internodes. Young tissues are most susceptible. Symptoms appear 21 to 30 days after infection. Rachis and berry infections become apparent later in the season. Infected rachises wither, causing berries or entire clusters to drop prematurely. Berries turn brown and shrivel.
Prolonged rainy, cold weather in spring and early summer promotes the disease. The optimum temperature for infection is between 59 and 68ºF (15 to 20ºC). The fungus overwinters in bark of infected canes.
Phomopsis cane and leaf spot occurs in most grape-growing regions.
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