Effect of temperature on induced systemic resistance to strawberry powdery mildew

Abstract: Various chemical and microorganisms provide effective control of strawberry (Fragaria × ananassa) powdery mildew (Podosphaera aphanis) and induce systemic resistance in this pathosystem. We tested the effects of temperatures between 15 and 25 °C on the severity of powdery mildew on strawberry and on systemic induced resistance to strawberry powdery mildew. The inducers acibenzolar-S-methyl (BTH), Trichoderma harzianum T39 (Trichodex) and nutrient broth (NB) and isolates of the yeast Rhodotorula glutinis and the bacterium Pseudomonas fluorescens effectively suppressed the disease when directly applied to the leaves or by inducing systemic resistance when applied as a drench. Powdery mildew of strawberry is affected by temperature; higher disease severity was observed at 20 °C. Temperature also had an effect on the observed disease suppression; induced systemic resistance was less pronounced at 15 and 25 °C than at 20 °C.