Oct 28, 2009
Sentinel Soybean Plots In Brazil Alert Farmers To Soybean Rust
Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.
Scientists have established a series of sentinel soybean plots in the cerrado regions of Mato Grosso and Goias in order to alert farmers to the presence of soybean rust. Four of the plots are in strategic locations in Mato Grosso and two are located in Goias. In each plot, early maturing soybeans are planted to serve as receptive host plants. These soybeans begin to flower and fill pods much earlier than nearby commercial fields, so they serve as an early warning system for the arrival of the disease. At each location, special traps are set up to capture any airborne soybean rust spores that may be in the area. This data is then analyzed by software developed by Bayer Cropscience, which claims 95% accuracy in predicting the arrival of the disease. After this early warning system was developed in Brazil, it was subsequently adopted by the USDA and is now in use in the southern United States.
Early detection and treatment for soybean rust is critical in avoiding yield losses. A soybean field can loose between 0.5 and 1.0 bushel per day of yield for each day that a severe case of soybean rust goes untreated. The earlier the disease enters a commercial soybean field the more costly it is to control because the fungicides used to control soybean rust are contact fungicides, which means they must be reapplied ever 25-35 days. Therefore, the earlier the disease moves into the field, the greater the number of treatments that will be required.
In Brazil, Embrapa has reported 16 cases of rust thus far this growing season. About half of the cases were reported in irrigated seed production fields and the other half was in volunteer soybeans. Tocantins is the state with the most cases followed by Parana. The state of Tocantins has very little soybean production, but Parana is the second largest soybean producing state in Brazil and soybean rust is the number one disease that affects soybeans in the state. Over the last two months, the rainfall in Parana has been very heavy, which has set the stage for an early appearance of the disease. Scientists and farmers in Brazil have become very proficient at controlling the disease, but the early arrival of the disease has farmers worried that control measures are going to be very costly this year.