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Expect more bean bugs this year

Between a mild winter, an early spring and favorable weather predicted for summer, the ag community is buzzing about the 2012 insect pest forecast. A dubious combination of warm temperatures and dry weather gave bugs the upperhand in overwintering success rates, and farmers may not have to wait long before they witness firsthand what kinds and how many of the pests will make an appearance in soybean fields this year.

Erin Hodgson, Iowa State University Extension entomologist, believes many of the usual suspects will appear in fields. “For soybeans, the soybean aphid and Japanese beetle are some of the most persistent pests we can expect. In Iowa, Japanese beetle is becoming more of a regular pest growers now have to take into consideration every year when managing beans.”

Key Points

Insect survival is expected to increase because of mild winter temperatures.

Scout crops and stay on alert for pressure in fields that had problems last year.

Insecticide seed treatments offer initial control of soybean insects.

Jim Frederick, a Syngenta agronomy service rep in southern Iowa, agrees that beetles will likely be the biggest problem plaguing growers this season. “University models predict the lowest mortality of bean leaf beetles since they’ve kept those types of records,” he says. “Not many of them perished over the winter, so we’re preparing for the possibility of bean leaf beetles to be somewhat prolific.”

While pests have posed the biggest problems in the past, it’s the mild winter temperatures and early spring that have folks concerned this year. “We had a very mild winter for temperature and amount of snow cover. Generally, warmer temperatures are good for insects. Those that aren’t cold-hardy and can’t normally survive sub-zero temperatures have a higher chance of surviving,” says Hodgson. “But on the other hand, the insects that depend on snow cover for insulation on those days that drop below zero are left fairly exposed.”

Early emergence in spring

The early arrival of spring also caused emergence of pests from their overwintering stages. Growing degree days, which predict pests’ overwintering development either through hatching from eggs or awakening in the adult stages, have been accumulating already this year, so it’s expected many pests will appear earlier than normal.

This year entomologists and agronomists are recommending that growers consider using an insecticide/fungicide seed treatment to help protect soybeans from early-season pests, primarily in fields with a history of early-season insect damage or in seed fields. Hodgson says bean leaf beetle, in particular, has a greater chance of survival during a mild winter, since they overwinter as adults. And when those adults survive, they’ll be hungry. “The first-planted soybeans that have insecticidal seed treatments should be fully protected, and growers should see very good control from those seed treatments,” she says.

“When using seed treatments, typically we see the overwintering bean leaf beetle adults knocked down with hardly any survivors, so we do see very good control,” says Hodgson of previous research conducted by ISU. “It also helps if you have early-season colonization of soybean aphid. However, it won’t help as much later in the season if you have emergence after bloom.”

For growers, this additional early-season protection may be just what they need to protect their crop’s yield potential. “CruiserMaxx Beans insecticide/fungicide seed treatment can provide excellent activity against a broad spectrum of seed and foliar-feeding insects,” says Frederick. “And if a follow-up foliar insecticide application is needed later in the season, Endigo ZC insecticide contains two modes of action for quick knockdown and extended residual control, to protect soybeans from significant yield loss.”

Growers who use insecticide seed treatments should still scout and make treatment decisions about those insects that migrate into fields after bloom, including late-season soybean aphid populations, as the season progresses.

Source: ISU Extension, Syngenta

This article published in the May, 2012 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2012.