Control of wheat diseases using phosphites and acibenzolar-s-methyl alone or associated with piraclostrobina + epoxiconazole

Abstract

The objective of this study was to evaluate the effect of different sources of phosphite to control leaf rust, powdery mildew, yellow and brown spot in the wheat crop in Palmeira, Paraná state, Brazil. The treatments were: four commercial sources of phosphites (A, B, C and D), applied at 1500 mL ha^-1, (applied in rate of active product) acibenzolar-S-methyl (ASM) at 500 mL ha^-1 (isolad or association),  pyraclostrobin + epoxiconazole (fungicide) at 400 mL  ha^-1) and phosphite A with pyraclostrobin + epoxiconazole (at 300 mL ha^-1), phosphite A with pyraclostrobin + epoxiconazole (400 mL ha^-1), acibenzolar-S-methyl with pyraclostrobin + epoxiconazole (400 mL ha^-1) and control (water), . The experimental design adopted was complete randomized blocks with four replications.  Regarding diseases, evaluations were done on the determination of severity and the calculation of the area below the curve of the disease progress in the flag leaf and entire plant. Leaf area index, thousand seeds weight, hectoliter weight and yield were also evaluated. Phosphite, independently source, did not act on leaf rust, powdery mildew, yellow and brown spot. The resistance inducer acibenzolar-S-methyl either isolated or associated to other fungicides affected leaf rust and powdery mildew of the wheat. Only phosphites associated to the fungicide controlled diseases, however there was no additional increase in yield whether compared to the control promoted by the fungicide.