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December 7, 2010

Samples from Mato Grosso Tested for Presence of Crazy Soybean II

Soybean samples from northern Mato Grosso have been sent to Embrapa laboratories in Goias to check for the presence of a disease called Crazy Soybean II. The disease was first discovered in Brazilian soybean fields several years ago and since then it has been found sporadically in central Brazil.

The organism that causes the disease is yet unknown and the origin of the disease is also a mystery. Soybeans affected by the disease do not mature normally and there is a high incidence of flower and pod abortion. Affected soybeans remain green while unaffected soybeans turn yellow and start to mature.

During the 2010/11 growing season the distribution of the disease and the severity varied by region, but it was mostly found in isolated fields in central and northern Mato Grosso. On a localized basis, the disease can cause economic losses, but on a statewide basis, it appears to be another disease that farmers must watch and try to manage.

In June of this year, researchers from Embrapa, agronomist from various federal universities, and agronomist from Aprosoja formed a working group to monitor the distribution of the disease and to try and ascertain the causal organism. In could be a virus, fungus, or bacteria, but speculation is that a virus may be the cause of the abnormality. Since all the soybean fields in Brazil receive fungicide applications to control soybean rust, this new disease is probably not a fungus. If it is a virus, then fungicide applications would have no affect on the disease. If it turns out to be a virus, then varietal selection would probably be the best way to control the disease.