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Bean Busters | What Farmers Should Watch for in Soybean Fields this Growing Season


They’re ba-aack. Extension entomologists around the Corn Belt expect to see aphids, white mold and other common pests and diseases this year. Of course, a lot depends on the weather.

“I expect it will be easy to find aphids on soybeans all over Ohio, especially in the northern part of the state,” says Ron Hammond, Ohio State University Extension entomologist. “But this does not necessarily mean economic populations. We have had some areas reach economic populations in odd-numbered years, and I expect that again. But, because we cannot predict, it’s necessary to scout, scout, scout.”

It will be necessary to scout for other pests, too. Hammond says the brown marmorated stink bug could be problematic. Erin Hodgson, Iowa State University entomologist, says early leaf defoliators, such as bean leaf beetles, could show up if conditions are favorable during soybean emergence. However, her main concern is also the soybean aphid.

That’s also what’s expected in Indiana. Purdue University Entomologist Christian Krupke expects the aphid to be the No. 1 potential pest. But, “things like slugs, wireworms and white grubs can be a problem if soils are cool and wet for extended periods after planting.”

Pests aren’t the only yield-robbers to watch for in your soybean fields this summer. Diseases will play a role, as well. They are, of course, dependent on weather conditions.

“If we have another wet spring then Pythium and Phytophthora should be expected. Soybean cyst nematode (SCN) and sudden death syndrome (SDS) are always potential problems for growers in Missouri. Frogeye leaf spot has been severe in localized areas the last few years so growers should be scouting for that disease,” says Laura Sweets, University of Missouri plant pathologist. “If it is a hot, dry year then charcoal rot might be a problem.”

Alison Robertson, Iowa State University plant pathologist echoes the differences weather can make.

“If it’s a cool, wet summer then white mold could be bad. It was a problem in 2009 and soybeans will be planted to those same fields this year,” she says. “SDS is likely if we have cool, wet conditions at planting, but unless we have very wet conditions throughout the season it probably won’t be at all like last year. SCN is our chronic problem.”

Again, basing predictions off the weather, University of Minnesota Plant Pathologist Dean Malvick sees similar issues to Iowa.

“Where rainfall is above average in June and early July in the southern half of Minnesota, I expect SDS to cause problems in some fields,” he says. “The same will be true for Phytophthora rot throughout the entire state.

“Where we have wet and cool conditions in July, I expect white mold to be a problem. Brown stem rot (BSR) is a problem throughout the state, and seems to be most severe when the season has average to slightly above-average rainfall in July and cool and dry conditions in August,” he adds. “SCN will cause problems like it does every year, especially in dry seasons, and the same goes for pod and stem blight.”

Kirsten Wise, Purdue University plant pathologist, repeats the concern for wet weather and what it will do for diseases.

“Planting conditions and the weather shortly after will influence disease development. If the soils are cool and wet at planting and emergence, it increases the likelihood that we’ll see seedling blights, Phytophthoraroot rot and SDS develop in soybeans,” she says. “Many fields that had problems with white mold in 2009 will be back in soybean production in 2011, and if weather conditions are cool and wet as soybeans flower, we could see white mold develop in certain areas.”

University of Wisconsin Plant Pathologist Paul Esker is expecting much of the same diseases in Wisconsin, along with BSR.

“We can't underemphasize the need for producers and others to split stems late in the growing season to look for Brown stem rot,” he says. “I think there has been less of this occurring, and we haven't always had the foliar symptoms of BSR occurring; we are seeing the B genotype.”

While this list isn’t concrete or an example of everything that may show up in your soybean field, it’s important to note of what’s expected and to scout throughout the growing season for these and other soybean pests and diseases.


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