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January 6, 2016

Four States in Southern Brazil Account for 90% of Rust Cases

Embrapa is reporting 217 confirmed cases of soybean rust in Brazil this week. The state of Parana has the most with 117, followed by Rio Grande do Sul with 60, Sao Paulo with 13, Mato Grosso do Sul with 13, Mato Grosso with 5, Santa Catarina with 5, Minas Gerais with 2, Tocantins with 1, and Goias with one. Last year at this time there were 100 confirmed cases of rust. The worst year in Brazil was 2009/10 with 343 cases at this time and the best year was 2011/12 with 16 cases. The 5-year average is 55 cases and the 10-year average for this date is 130.

Several things stand out this year concerning soybean rust in Brazil. The number of rust cases thus far have consistently been about 3-4 times more than the 5-year average and the four southern states in Brazil (Sao Paulo, Parana, Santa Catarina, and Rio Grande do Sul) account for 90% of all the soybean rust cases in Brazil. The state of Parana alone has 54% of all the rust cases in Brazil. This is understandable give the torrential rains that have fallen across southern Brazil over the past several months.

Another significant trend this year is that there has not been any rust reported in commercial soybean fields in the state of Mato Grosso. Certainly, this is the result of the hotter and dryer than normal conditions that have persisted across the state in recent months. Even if a few cases of rust start to be reported in Mato Grosso in January, the disease will probably not be a major factor in Mato Grosso this growing season.