Analysis of combined strategies for the management of Asian soybean rust

Abstract

Asian soybean rust, if not well managed, can reduce grain yield up to 90%. Due to the severe damage caused by the disease, especially in Brazil, it is important to evaluate management strategies combined with fungicides, to minimize the losses. The aim of the work was to evaluate the effect of adopting different combined management strategies on the severity of soybean rust and its impact on the performance of the crop. Research was carried out at 2016/2017 and 2017/2018 growing seasons. Soybean cultivar NA 5909 RG® (susceptible to Asian rust), LG 60163 IPRO® (highly tolerant) and TMG 7062 IPRO® INOX® (resistant) were evaluated with different combinations of fungicide, copper and potassium phosphites foliar fertilizers applications, in two development stages, R 1 (early flowering) and R 5.1 (early grain filling). Disease severity assessments were performed at R 1 and repeated every 14 days (up to R 5 + 14 days) to determine the area under the Disease Progress Curve (AUDPC). The genetics of resistance to Asian soybean rust contributed to the less progress of the disease in plants. Even with differential responses between cultivars and treatments applied to the severity of Asian soybean rust, the disease did not compromise grain yield in both growing seasons.

Performance of dual and triple fungicide premixes for managing soybean rust across years and regions in Brazil: A meta‐analysis

“…However, the sole use of resistant cultivars as a management choice has the same limitation as the use of fungicides: the selection of pathogen populations capable of overcoming the Rpp genes (Godoy et al, 2016a). Therefore, recent studies have investigated interaction effects of chemical and genetic control (Bahry et al, 2020; Sacon et al, 2020). A two‐year study (2016/17 to 2017/18) conducted in Paraná state found a significant reduction in SBR severity when combining fungicide treatment (AZOX + BENZ) with a resistant cultivar (TMG 7062; c.72%); slightly less reduction was obtained when fungicide was combined with the highly tolerant cultivar LG 60163 (c.64%) and less still with the susceptible cultivar NA 5909 (c.52.1%) (Bahry et al, 2020).…”

“…Therefore, recent studies have investigated interaction effects of chemical and genetic control (Bahry et al, 2020; Sacon et al, 2020). A two‐year study (2016/17 to 2017/18) conducted in Paraná state found a significant reduction in SBR severity when combining fungicide treatment (AZOX + BENZ) with a resistant cultivar (TMG 7062; c.72%); slightly less reduction was obtained when fungicide was combined with the highly tolerant cultivar LG 60163 (c.64%) and less still with the susceptible cultivar NA 5909 (c.52.1%) (Bahry et al, 2020). Sacon et al (2020) also reported higher SBR control applying AZOX + BENZ to resistant cultivars (>80%) compared to a susceptible one (c.56%) in field experiments conducted in northern Rio Grande do Sul state during 2016/17 and 2017/18 growing seasons.…”