Soybean rust has been confirmed on soybeans in Colquitt County (9/09) and Burke County (9/11).
Consider spraying a fungicide on your soybeans if:
- They have reached R2/R3 growth stage and not yet reached R6 growth stage.
- Have good growth and reasonable yield expectations.
- This is especially critical if soybeans exhibit good growth and full canopy of foliage.
The strobilurin and chlorothalonil fungicides are protectants and offer little or no curative activity. The triazole fungicides provide protective as well as curative benefits. All of the fungicides are best if used prior to infection or early in the infection process to be most effective.
When spraying soybeans for soybean rust, it is important to get complete coverage of the plant. Ground applications should use at least 15-20 gal/acre spray volume and aerial applicators should use 5 gal/acre spray volume. Selecting nozzles that will give you thorough coverage from the top to bottom of the plant is the key to success. Choose the appropriate size and type of nozzles and operate them at a pressure that will allow them to produce fine to medium spray quality. Flat-fan nozzles are better than cone nozzles because they produce fewer very fine, drift prone droplets. Spray pressure of 50 psi or greater will more than likely be needed to maximize coverage.
The yield potential looks good for many soybean fields in the county at this present time. Hopefully, timely rains will continue to advance the crop through pod fill. Remember that cool and wet weather conditions favor the spread of soybean rust.