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December 10, 2014

Rust found in Commercial Soybean Fields in three Brazilian States

The Brazilian Agricultural Research Service, Embrapa, has confirmed that soybean rust has now been found in commercial soybean fields in three Brazilian states - Mato Grosso, Parana, and Sao Paulo. Embrapa has confirmed 47 total cases of the disease in Brazil with 35 in volunteer soybeans and 12 in commercial fields. The disease has been identified in commercial soybean fields about 15 days earlier than it was last growing season.

Scientists are alerting farmers that as soon as the disease is identified in their region they should be ready to apply a preventative fungicide application. Any delay in applying the fungicides after symptoms appear in the field can result in lower yields. How fast the disease may spread across Brazil will depend on the amount of spores present, the age of the soybean plants, and the climatic conditions.

If soybean rust is not adequately controlled, it can prematurely defoliate the plants before the normal grain filling process is complete resulting in lower yields. The cost of the disease including control costs and lost production averages about US$ 2 billion per year in Brazil. Scientists are advising farmers to use a variety of fungicides with different modes of action to slow down the development of rust resistant to a particular fungicide.

Of the 47 cases of rust identified in Brazil, 18 have been found in Rio Grande do Sul and 16 in Mato Grosso. The state with the most cases last growing season was Goias at 106. The disease has already been found in Goias and farmers are worried that it could be a bad year for the disease. The soybean crop in the state was planted about two weeks later than normal this year which means the crop will be exposed to the disease two weeks longer than normal as well.

Approximately 20% of the soybeans in Goias were planted before the dry weather in October which halted planting for about three weeks. The drought impacted the plant populations of the early planted soybeans and some of the fields ended up being replanted.