Bin run seed – some lessons from the past
Source: Dr. Anne Dorrance; OSU Soybean Pathologist With lower prices and higher input costs in today’s soybean farming operations, some farmers are looking to shave a few dollars off their costs of production. Based on the calls directly from farmers on which seed treatments to use, it is not too hard to figure out where some of those savings might be coming from. This used to be general practice but there are ways to do this to be sure it really is saving money.
Make absolutely sure that this seed is a candidate to use again. The harsh reality of the new generation of technologies that go into the new soybean varieties is that it probably takes the total profit of the U.S. soybean crop to go from discovery, development, U.S. and European government approvals, and producing that seed. Companies are forced to protect that investment, and in reality, part of how we have raised the state yield average is because of these improved varieties.
Make sure the seed is healthy. Germination tests are very important. It was a tough fall and as you look at that seed there may be a lot of discolored, moldy seed from Phomopsis or Cercospora. There may also be splits – as some seed was harvested last fall well below 13 percent. So this will reduce your viability. (University of Kentucky Regulatory Services do have germination tests that they can perform for producers.) Also, for testing at home, use a baking dish, line it with paper towels, and run water over it, drain the excess water, then scatter 100 or more seeds over the bottom of the dish. Cover again with more paper towels, add just enough water to moisten that top layer. Leave on the counter or in a warm room for five to six days, keeping the seed moist but not swimming in water, and check the germ.
If it is not over 85 percent, it is probably best to buy new seed. (Note use several pans from seed collected from the different fields.)
Don’t repeat problems or diseases from last fall. Three different pathogens can be carried with seed:
• Sclerotinia: stem rot or white mold - the sclerotia, those hard black irregular shaped structures, can be harvested with the seed and then, if not properly cleaned, can end up back in the soil in the seed furrow. Also, some seed will have mycelium of the fungus, that white fluff that you see on the stems. This can also contribute to poor stands in the spring. (White mold is not typical in Kentucky.)
• Phomopsis: seed decay - this disease will directly impact seed viability. But some seed will carry the fungus on the outer layers, but it won’t have reached the internal layers. When a fungicide that targets this fungus is used, germination of the seed lot can be improved.
Again, if overall germination is below 85 percent and the seed is really moldy, best to get new seed.
• Purple seed stain. Cercospora blight, in addition to frogeye leaf spot, made a late season appearance in some areas.
What seed treatments will work to protect germ and limit spread of these pathogens? Most of the data available today is based on Phomopsis, and there are a number of active ingredients that can protect seed – when the seed is contaminated with mycelium but not the germ, and when an infected seed is placed right next to a healthy seed in the seed furrow. Look for seed treatments that have one of the following active ingredients: fludioxonil, fluxapyroxad, ipconazole, PCNB, penflufen, prothioconazole, pyraclostrobin, or sedexane. Data is from the combined studies of members of the NCERA-137 Soybean Pathologists from the Land Grant Colleges in the soybean producing states.
The most important advice is to rotate fields. In addition to the ability to survive or contaminate seed, all of these pathogens have survival structures in the soil or on soybean residue. To get off on the right foot for 2018, plant fields that have problems, lower yields, plants with symptoms of early dying from a plethora of problems, or moldy seed to corn preferably. Or if you must plant soybeans, work with your seed dealer to get the best disease resistance package in that field. We can solve all of these problems by planting varieties with better disease resistance packages targeted for our areas. For more information on soybean varieties, or germination tests, contact the Woodford County Extension Service at 873-4601.