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February 9, 2015

254 Cases of Soybean Rust in Brazil, Slight Increase over Last Week

Embrapa is now reporting that there have been 254 confirmed cases of soybean rust in Brazil which is only slightly more than the 242 cases reported last week. The state of Parana leads with 82 cases followed by Rio Grande do Sul with 64, Goias with 34. Mato Grosso with 31, Mato Grosso do Sul with 19, Sao Paulo with 15, Santa Catarina with 8, and Minas Gerais with 1.

The nine-year average of confirmed cases of rust for early February is 800, but if you look at just the last four years, the average is 284 cases. The worst year for soybean rust was the 2009/10 growing season with 1,667 cases were reported by the first week of February. The best year was the 2011/12 growing season when there were 189 confirmed cases by early February.

The number of confirmed cases of soybean rust in Brazil have been increasing slower than normal. Last week there were 16 cases more than the four year average (242 vs the average of 226) while this week, there are 30 cases less than the four year average (254 vs the average of 284). If you look at the nine years for which data is available, last week the number of cases (242) was 37.9% of the nine year average (638), whereas this year the number of cases (254) is 31.7% of the nine year average (800).

While the rate of increase may be slowing, agronomist in Brazil are advising farmers not to let their guard down concerning soybean rust. Farmers may be tempted to save some money by forgoing the last fungicide treatment, but rust is often referred to as the "silent yield robber" and yield losses can occur if the disease is not controlled all the way through to the end of the season.

With that said, there are enough soybeans in Brazil either mature or approaching maturity that I think we can say that there is not enough time left in the growing season for rust to become a significant factor in the 2014/15 Brazilian soybean crop.