Farmers who are tempted to tank mix a soybean rust preventative fungicide with a scheduled herbicide treatment should reconsider their options.

Researchers at Purdue University point out that the timing for weed control and the timing for soybean rust treatments don’t match up very well. And spray techniques that are good for herbicides (low pressure and large droplets) are typically not effective for fungicide treatments that must get up under the canopy to be effective.

The researchers say that insecticide treatments for soybean aphids could possibly be a better match for tankmixed fungicide treatment. Scouting soybean crops for rust and aphids can be done on the same walk through the field, for example. But farmers should be careful not to apply fungicide or insecticide unless the applications are necessary.

For more information on tank mixing fungicides, read "Fungicides, Herbicides and Soybean Rust: Do They Mix?" by Greg Shaner, Glenn Nice, and Bill Johnson. The publication can be downloaded online at www.btny.purdue.edu/weedscience/2004/articles/herbfungmix04.pdf.