Dec 23, 2021

Rio Grande do Sul Institutes a Soy Rust Spore Monitoring Program

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

On November 29, 2021, Emater in conjunction with the state Secretary of Agriculture and various research institutions in the state of Rio Grande do Sul in southern Brazil, inaugurated the Program to Monitor Rust in Rio Grande do Sul ( Programa Monitora Ferrugem RS). The goal of the program is to monitor the presence or absence of soybean rust spores in the state and to help advise farmers on the best time to apply fungicides to control the disease in the most efficient way possible.

A similar program has been in effect in the state of Parana for several years and it has greatly reduced the number of fungicide applications needed to control soybean rust. Prior to the program to monitor the presence of rust spores, farmers had been applying fungicides on a calendar basis instead of a need basis.

During the 2020/21 growing season in Rio Grande do Sul, they installed 24 spore collection devices and that has been expanded this growing season to 46 collection devices in 44 municipalities.

The director of the program, Elder Dal Pra, feels this information concerning the presence of spores is extremely valuable for farmers when they are making the decision to apply fungicides or not. The program also monitors the local climatic conditions which can help in determining how fast the spores may spread. This information can help farmers plan their treatment options to control the disease most effectively.

Thus far this growing season, there have only been 5 confirmed cases of soybean rust reported in Brazil, 3 in the state of Sao Paulo, 1 in Minas Gerais, 1 in Parana , and I in Roraima. Spores have been detected in Rio Grande do Sul, but no rust has been confirmed in commercial soybean fields.

This is the fewest number of rust cases in Brazil in the 16 years that Embrapa has been monitoring the disease. The weather in southern Brazil has been dryer-than-normal for the last few months, which has probably slowed the spread of the disease.