February 8, 2011

Incidence of Mad Soybean II Declines in Mato Grosso

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

There was a lot of media attention earlier in the growing season devoted to the discovery of an anomaly called "Mad Soybean II" in the soybean fields of Mato Grosso as well as other locations in central Brazil. After the initial concern that the anomaly could cause significant losses in the state, it now appears that the incidence of the anomaly in 2010/11 is actually lower than in 2009/10.

When there is a severe case of the anomaly, it does result in significant yield reductions, but generally only on a localized basis. In Sinop, which is located in northern Mato Grosso, a farmer named Gilmar Bellini reported that 20% of his 500 hectares of soybeans had been infected during the 2009/10 growing season, but the level of infection was much lower this growing season.

The symptoms of the anomaly include a high level of flower and pod abortions, disfigured leaves and pods, and the plant staying green instead of maturing. In severe cases, the soybean yields can be cut 30 to 50%.

Teams of scientists are closely studying the plants that have demonstrated the symptoms of the anomaly in an attempt to pinpoint the cause. There appears to be a correlation between the number of volunteer soybeans left in Brazilian soybean fields during the dry season and the occurrence of Mad Soybeans. If there are less volunteer plants, there appears to be lower incidences of the anomaly.

The anomaly affects conventional as well as GM soybeans, in no-till and conventional tillage, and under various herbicide regimes. The anomaly appears to be more common in areas that have higher temperatures during the growing season.

Researchers feel one potential cause of the anomaly might be insect attacks, but they are not sure if it is the insect causing the problem or a disease transmitted by the insect. They are still trying to identify the cause of the problem and they cannot give producers any concrete advice on how to avoid the problem in the future.