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Some pests coming on early

Jeff Caldwell 06/04/2012 @ 2:36pm Multimedia Editor for Agriculture.com and Successful Farming magazine.

The bugs are on the move.

Soybean aphids, Japanese beetles and Black cutworms are just a few of the insect pests agronomists are finding in the field, some a couple of weeks earlier than normal. Iowa State University entomologist Erin Hodgson says the last 2 weeks have featured reports from farmers of these bugs, some already causing economic damage.

Take the Black cutworm, for example. Hodgson says there have been reports of "significant stand loss due to feeding and clipping in young corn," some severe enough to warrant replanting in cases where it's still possible.

"Some late-planted corn fields are being replanted in southeastern Iowa this week due to stand loss by black cutworm. I recommend scouting for black cutworm until corn reaches V5," Hodgson says.

One pest that's arrived earlier than normal by as much as 2 weeks is European corn borer. Right now, Hodgson says the eggs and young larvae are present in many fields. If you planted corn varieties susceptible to corn borer damage, it's time to scout.

"Older, non-traited corn should be scouted now to estimate densities," she says. "Tracy Cameron, an agronomist near Creston, also found a few corn earworm caterpillars in young corn. This is a little early to see corn earworm in Iowa, but most insects are showing up 1-2 weeks earlier than normal."

The Japanese beetle's another bug that's making its appearance earlier than normal. Usually, it's mid-June before this bug even makes an appearance, and it's typically later when damage is most common.

"We don’t typically see adults until mid-June in Iowa, but our mild winter has accelerated insect development. Japanese beetles have also been reported in other states like Illinois," Hodgson says. "They could be pests in corn and soybean later in the season, but keep an eye on their population densities in June."

Finally, soybean aphids nymphs -- not too uncommon this early in the year -- were observed last week in northeastern Iowa. Though it's not that much earlier than normal, Hodgson says it's a good reminder to keep an eye out for this bug from now through the summer.

"You may need a hand lens to see first instars on small plants," she says. "Often I confirm early-season colonies in soybeans by looking for ants and lady beetles."

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