If we could predict or know that the planting season during 2014 would be like it was in 2012 (the dry spring), then Ohio State University experts would say don’t treat your seed at all. But if the season is like this past year, wet, the combinations of seed treatments did a much better job and at the higher rates. There have been lots of questions recently, regarding which fungicides to apply, which rates to use and the necessity of insecticides.
Metalaxyl (numerous companies) & Mefenoxam (Syngenta)
These products are targeted for most of the water molds. Damping-off, seed rot and poor stands are the primary symptoms that occur in the field, but at the end of the year – yield benefits can be measured. The two active ingredients are applied at totally different rates. For Metalaxyl – typical rates are 0.2 (low), 0.75 (medium) or 1.5 (high) fl oz/cwt and mefenoxam is applied at 0.16 (low), 0.32 (medium), and 0.64 (high) fl oz/cwt.
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Our data from fields with optimum disease conditions, both at the research branches and on farm have shown that the higher rates provide for significantly higher stands (thus no replant), as well as higher yield at the end of the season. Some companies have begun to drop the rate, which is fine for other states and areas of Ohio where the soils are better drained and there is little pressure from Phytophthora.
However, for producers that farm poorly drained fields, no-till, continuous soybean or soybean/corn rotation, and have a history of replant are the most likely to see the added benefit of higher rate of seed treatment. Work with your seed dealer to figure out which active ingredient he has and then which rate is most appropriate for your field conditions and history.