A combo fungicide best known for disease control in wheat, oats and barley has picked up approval for use against soybean leaf diseases including Asian soybean rust. Bayer CropScience’s Group 3 and 11 combination Stratego 250 EC is usually applied at lower rates (202 milliliters per acre) on cereal crops but has been approved for use at 500 ml/ac. against Asian soybean rust and frogeye leaf spot in soybeans.
The product includes propiconazole, the Group 3 active ingredient in fungicides such as Syngenta’s Tilt and Quilt, and trifloxystrobin, the Group 11 active in seed treatments such as Bayer’s Prosper FX and Trilex AL.
The company recommends applying Stratego before disease is present for best results, but said a preventive application should occur at the very early stages of disease development or between growth stages R1 to R5.
“Crop scouting for soybean diseases is important, but in practice the decision to use a fungicide often comes down to economics. By the time disease effects are visible, it is often too late to spray,” the company says. That is, an application should be considered “if your soybean crop looks good, with the potential for high yields and high quality,” Bayer said.
Soybean leaf diseases are responsible for an estimated 10 per cent yield loss, according to Bayer, citing data from independent trials as well as its own tests between 2007 and 2010. Sixteen on-farm trials in Ontario and Quebec during a “mostly disease-free 2010” turned up an average yield increase of two bushels per acre with Stratego, compared to untreated soybeans.