Blueberry powdery mildew

The disease is caused by the fungus Podosphaera myrtillina, a member of the Erysiphaceae family. As an obligate parasite, it survives and replicates by extracting nutrients directly from the host plant's epidermal cells, leading to physiological stress.

The primary hosts of this pathogen include members of the Ericaceae family. Blueberry (Vaccinium) species are particularly susceptible, with commercial plantations often facing significant yield losses if the environmental conditions favor the rapid proliferation of the fungal mycelium.

Symptoms typically manifest as a white, flour-like coating on the foliage and new shoots. As the infection progresses, the leaves may curl, turn chlorotic, or drop prematurely. The presence of tiny, dark, spherical structures known as cleistothecia indicates the sexual stage of the fungus.

Environmental factors are critical for the spread of Podosphaera myrtillina. Warm temperatures and high humidity facilitate the germination of conidia, while stagnant air within dense, poorly pruned canopies allows the infection to spread rapidly from plant to plant via wind dispersal.

The impact of this disease is significant, as it reduces plant vigor and fruit quality. Effective control strategies involve a combination of chemical intervention using fungicides, as well as cultural practices that improve airflow, reduce moisture accumulation, and eliminate overwintering inoculum sites.

• Application of sulfur-based or systemic fungicides.
• Pruning to ensure adequate air circulation.
• Removal and destruction of infected plant debris.
• Monitoring the field throughout the growing season.