Efficiency Loss of Recorded Fungicides for the Control of Asian Soybean Rust in Central Region of Brazil

Abstract

Due to grower allege of low efficiency of triazole fungicides in recent years in Central Brazil on the control of Asian soybean rust (Phakopsora pachyrhizi), this study was undertaken to demonstrate the efficiency loss of products registered for rust and applied alone and to evaluate the efficiency of fungicides mixtures. The trials were carried out in five locations in Brazil, in the 2009/10 growing season. The experimental design was completely randomized blocks with four replications. Ten mixtures of triazole + strobilurin and two applications of pure triazoles were evaluated and the control without application. The application of fungicides started in the R1/R2 stage or in any vegetative stage if infections occurred early. The mixtures of fungicides were effective in controlling Asian soybean rust. Application of sole triazole fungicides was less effective in controlling the rust than the mixtures of triazoles + strobilurins. The use of commercial mixtures of triazole with strobilurin for rust control is recommended.

Analysis of combined strategies for the management of Asian soybean rust

“…Since the disease entered Brazil in 2001, many products have been tested. Over the years, some products previously very efficient, have ceased to be recommended, especially in isolated use; while others have shown promise, especially in mixtures (Aguiar et al, 2016;Reznikov et al, 2019;Zuntini et al, 2019). These differential responses of fungicide efficiency, during the crop years, are due to the variation of the fungus in the environment, with the appearance of less sensitive populations and even resistant to the currently available fungicides *Corresponding author.…”

Análise de cruzamentos dialélicos para o desenvolvimento de soja tipo hortaliça com tolerância à ferrugem

“…A estratégia de controle mais recomendada é a utilização de diferentes fungicidas combinados com cultivares que apresentam tolerância ou resistência à doença. É imprescindível que exista a combinação destes dois fatores pois apenas a utilização do controle químico pode exercer uma maior pressão de seleção sobre populações de patógeno (Aguiar et al 2016), que por sua vez apresentam grande diversidade, podendo levar, em um curto espaço de tempo, à perda da eficiência das moléculas ativas. Além disso, a tolerância ou a resistência genética permitem a minimização da aplicação de fungicidas, fato que também favorece a obtenção de produtos mais apropriados para o consumo humano in natura.…”