Seed treatments for 2014 soybean
If we could predict or know that the planting season during 2014 would be like it was in 2012 (the dry spring), then we 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 over the past few days on what fungicides to apply; what rates to use; and are insecticides always necessary. Here we try to parse it all out for you.
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.
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.
Several active ingredients of this chemistry have been added to the seed treatments over the past few years. They have a limited spectrum of activity, but for the most part they are contributing to etter stands and yield under Ohio’s conditions. Some of the strobilurins have activity towards some but not all of the Pythium spp. This is giving an added benefit to the soils with poor drainage, no-till and where even with the high rate of metalaxyl or mefenoxam, control was not optimal.
Some of the strobilurins are also good on Phomopsis, a fungal disease that is seed borne. Seed lots with less 70% germination should not be planted, but those with 70 to 90% germination can see an improvement in germination when treated with pyraclostrobin (BASF) but not azoxystrobin (Syngenta) or trifloxystrobin (Bayer). I have no idea why there is specificity here, but there is.