Farmers in Brazil have officially been notified by scientist of rust being detected in commercial soybean fields in Sao Paulo and Parana. Although rust is far from unusual, it is about a month early in being evident. Persistent wet conditions throughout southern Brazil associated with El Nino, have perpetuated the growth of the crop eating disease. Normal weather conditions would bring sporadic frosts and kill rust, but that has not been the case this year and has allowed the soybeans to profligate.
Currently, Embrapa has reported 66 confirmed cases of rust with 11 of those being cases in commercial fields. Most cases were found in soybeans that germinated after being spilled during harvesting or in transport. These volunteer soybeans can harbor the disease in between growing season and is the main reason why most Brazilian states have adopted a soybean-free period during which land owners are directed to destroy all live soybean plants.
Finding rust in commercial fields does not mean that the entire soybean field will be effected, but it does mean that farmers will be spending more on fungicide to control the disease. Farmers are therefore more concerned because chemical costs have risen this year due to a further depreciation of Brazilian currency. The higher costs mean even lower profit margins.
Farmers are asked not to use less expensive chemicals, rather use the most effective chemicals and to rotate them in order to put less pressure on the disease to develop a resistance to the fungicides. The recommended system has proven most effective. The 10-year average for the number of cases per year is 1,389, but just over the last five years the average is dramatically lower at 428 cases.