Powdery mildew of grapevine

Erysiphe necator is a biotrophic fungal pathogen belonging to the Kingdom Fungi and the Phylum Ascomycota. It is the primary cause of powdery mildew, a devastating disease affecting grapevines (Vitis vinifera) globally, which thrives by parasitizing the epidermal cells of green host tissues.

The biological cycle of the fungus involves overwintering either as mycelium within dormant buds or as cleistothecia in bark crevices. When favorable conditions return in spring, primary inoculum is released. The pathogen produces chains of conidia, which are wind-dispersed to young leaves and clusters, leading to secondary infections throughout the growing season.

The development of the disease is favored by warm, humid conditions with temperatures ranging from 20°C to 27°C. Unlike many other fungal diseases, Erysiphe necator does not require free water on the leaf surface to germinate; however, moderate to high humidity is essential for the colonization of the host tissue and the production of new spores.

The economic impact of the pathogen is significant. Infected berries often fail to develop normally, leading to skin rupture and exposing seeds, which severely compromises fruit quality and yield. Furthermore, heavy infestation causes premature senescence of leaves, reducing sugar accumulation and affecting the overall vigor and cold hardiness of the vine.

Management and control strategies rely on a combination of cultural and chemical practices. Cultural control involves canopy management, such as thinning and leaf removal, to improve air circulation and sunlight penetration. Chemical control includes regular applications of sulfur-based products or systemic fungicides like triazoles and strobilurins, timed according to the vine's phenological stages.