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Erysiphe (Uncinula) necator

Powdery mildew on grape

Description

Erysiphe necator is the fungal pathogen responsible for powdery mildew on grapevines. Originally classified as Uncinula necator, it is now recognized as Erysiphe necator. Originating in North America, it spread to Europe in the 19th century and is now widespread in vineyards across the continent. The fungus overwinters in buds and spreads to new shoots in spring, continuing to multiply and attack all green parts of the plant. Erysiphe necator thrives in warm, dry conditions, with optimal temperatures of 24–28°C and humidity levels of 70–95%. The highest risk of infection occurs in June and July. Freezing temperatures of at least -15°C during winter can effectively kill the fungus. As one of the most economically significant fungal diseases in viticulture, Erysiphe necator requires careful control to prevent crop losses and maintain fruit quality. E. necator significantly damages grapevines by reducing photosynthesis, weakening the vines, and leading to poor fruit development. If left untreated, it can cause substantial crop losses.

Symptom

White, powdery fungal growth on leaves, shoots, and grape clusters. Distorted, stunted growth of leaves and fruit. Reduced fruit quality and yield.

Tree Species: Grape

Part of a plant- attacked: Leaf / Needle, Fruit / Seed, Branch

Pest significance: Very harmful

Pest Category: Fungi

Invasive Species: Yes

Present in EU: Yes