Fungicide mixtures to control Asian soybean rust control in regions of Brazil

Abstract

High soybean grain yield is based on adequate crop management, mainly on disease prevention and control, especially
Asian soybean rust (ASR), which causes great crop damage. This study aimed to evaluate the ASR chemical control with diff erent
fungicide mixtures in three soybean-producing areas in Brazil during two consecutive crop seasons. Four fungicide treatments
[T1: benzovindyflupyr + picoxystrobin, T2: benzovindyflupyr + azoxystrobin, T3: fluxapyroxad + pyraclostrobin, and T4:
inpyrfluxam + tebuconazole] were evaluated with five replications. Phytotoxicity damage, ASR disease severity, plant
defoliation, 1,00 0 -grain weight, and grain yield were evaluated. The results were relatively consistent among all regions and between
the crop seasons, indicating that the treatments have similar responses when applied in diverse conditions. The T3 and T4 treatments
presented higher phytotoxicity, lower disease severity, lower plant defoliation, and higher 1,000-grain weight and grain yield.
The presence and damage caused by ASR tend to increase after the second soybean crop season in the same area, suggesting a
loss of efficiency of the evaluated fungicides.