Evaluation of Strawberry Host Plant Resistance to Powdery Mildew in 38 Genotypes Under Greenhouse Conditions in San Luis Obispo, California, Winter 2026

Podosphaera aphanis , the causal agent of strawberry powdery mildew, is an economically important disease that infects all above-ground plant parts. Signs of the pathogen appear as white powdery patches of mycelia, on both sides of leaves. This report evaluates the host resistance to powdery mildew of 38 cultivars and elite breeding lines (genotypes) under greenhouse conditions in San Luis Obispo, California, in winter of 2026. Weekly assessments of disease incidence and severity were evaluated. The results of this study will provide strawberry growers with information to make informed decisions on selecting resistant cultivars for effective powdery mildew management.