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| OSU specialists discover tools to combat soybean pest |
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The benefits of cover crops continue to grow. Touted for conserving soil while filling forage needs, some plant varieties also have the potential to suppress soybean cyst nematode (SCN) populations in no-till fields.
Ohio State University researchers have found that Italian ryegrass (also known as annual ryegrass), when planted as a fall cover crop, reduced soybean cyst nematode egg populations 30 percent to 50 percent in a single growing season. Additionally, researchers discovered that Italian ryegrass reduces weed populations by as much as 50 percent, including purple deadnettle which is a prolific overwintering host for soybean cyst nematode.
Kent Harrison, a weed ecologist with the university’s Ohio Agricultural Research and Development Center, said that the findings offer an additional tool for managing SCN, a small round worm that can cause significant yield reductions in soybeans. Soybean cyst nematode is the #2 soybean pest in Ohio, behind Phytophthora root rot.
When it comes to preparing to manage your soybeans, one of the best sources of information is right beneath your feet – the field’s history. Anne Dorrance, plant pathologist with the Ohio State University Extension, said let the field do the talking when it comes to managing soybean cyst nematode and seedling diseases.
“Problems with SCN and seedling diseases don’t just occur out of nowhere,” said Dorrance. “They slowly build up over time, so you can take your last field history, or several years of field history, and use that information to help you make a good planting decision for this season.”
Dorrance said that growers with a history of soybean cyst nematode should test their fields for cyst populations and make planting decisions for resistant varieties based on the results. The challenge, said Dorrance, is that not all resistant varieties will be completely effective against the various cyst biotypes found in Ohio. “We are receiving more and more reports that soybean varieties with cyst resistance source PI88788 are not performing the way we expect them to. The cyst populations are not going down when growers are planting resistant varieties. That’s telling us that the nematodes are adapting,” said Dorrance.
“A rotation with non-host crops still works as the best tool for managing SCN populations. We are not advocating growing cover crops as a substitute for annual crop rotations in pest management,” said Harrison. “We see this work as just providing another tool for managing the pest with something that has multiple uses, benefits the soil, as well as acting as a short-term grazing crop. Italian ryegrass can do all of these.”
In addition to SCN, soybean growers are also faced with seedling diseases, such as Phytophthora and Pythium. “With the cost of seed, growers can’t afford to replant anymore. Treat your seed if you’ve ever had to replant,” said Dorrance. “If producers have had a history of replant problems, where they are replanting three or four times, the first thing is to improve the drainage. Next look at your seed treatment component because just one seed treatment compound is not going to give you complete effectiveness over this whole range of diseases.”
For updates on Ohio’s soybean crop as the season progresses, refer to OSU Extension’s Agronomic Crops Team website at: http://agcrops.osu.edu |
| 4/30/2009 |
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