Phosphites and acibenzolar-S-methyl alone and combined with fungicides for the control of biotrophic pathogens of wheat

ABSTRACT Damage to wheat crop is associated with leaf rust (Puccinia triticina) and powdery mildew (Blumeria graminis f. sp. tritici). The present study aimed to evaluate the effect of potassium phosphite and acibenzolar-S-methyl alone or associated with the fungicide epoxiconazole + pyraclostrobin on powdery mildew and leaf rust control, as well as on grain yield. The experiments were designed as randomized blocks with four replicates consisting of plots with 17 planting rows spaced at 0.17 m, with dimensions of 2.89 x 5.0 m each. Severity of powdery mildew and leaf rust was assessed in ten flag leaves and ten whole plants all over the crop season; yield was also evaluated. Severity data were used to calculate the area under the disease progress curve. There was no effect of phosphite applied alone or associated with the fungicide epoxiconazole + pyraclostrobin at different times on mildew. Acibenzolar-S-methyl controlled, on average, 70% powdery mildew. Phosphites applied alone and/or associated with the fungicide had an effect on leaf rust, reducing the severity by 59 and 62%, compared to control. Applications of phosphites alone did not affect the yield components.