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Corn+Soybean Digest

Insect Indications For 2005

Forecasting pest pressures is unpredictable because insect populations depend, in large part, on the forecast. But entomologists know there will be insect pressures every year, in every state.

“Weather really influences insect populations,” says Marlin Rice, entomologist at Iowa State University. “There's a vulnerable point in each insect's life cycle. If we get a lot of rain or if it turns extremely dry, populations can go down.”

Besides the weather, insect populations can blow in with the wind, some seemingly overnight.

“There's always the potential for insects like black cutworms,” says Rice. “There's always migration, and we never know where they're going to stop and lay eggs.”

Here's what entomologists from 12 states say will be bugging you in 2005.


“The huge capture of winged soybean aphids means we're set up for a large aphid population in 2005. But, the weather could easily throw a wrench in the works. If the weather is like it was in 2003 or 2001, then we'll have soybean aphid problems.

“Rootworms in 2004 were awful. So with those extremely high numbers in last year we can anticipate a repeat in 2005.

“Japanese beetles are always problematic somewhere in Illinois. There hasn't been a year in recent memory where we haven't had a localized outbreak.”
Kevin Steffey, University of Illinois


“Western corn rootworm has the potential to have considerable negative impact on first-year corn fields; especially in areas of southwestern Indiana.

“Though some are predicting high soybean aphid populations, summer weather will be the determining factor. Rapid aphid buildup is favored by cooler temperatures and soybean fields under stress (e.g., drought). You may have heard that the stage is set for a big soybean aphid year. But I firmly believe it will take more than heavy 2004 fall flights and low predator numbers to equal aphid outbreaks in 2005.”
John Obermeyer, Purdue University


“Soybean aphids have the potential of causing more damage in 2005 than they did in 2004. But I wouldn't be so bold as to claim that soybean aphids are going through known cycles. If conditions turn dry in July and August there is potential for a significant number of acres to be economically impacted by soybean aphids.

“The bean leaf beetle is not a concern right now. The exception is early-planted beans, which are still susceptible.

“Western bean cutworm has been a problem in western Iowa for several years. The two-county tier that borders the Missouri river has been hit very hard over the last four years.

“We always have the potential for rootworm problems. If we get a lot of rain in the last week of May or the first couple weeks of June, it can drown a lot of the hatching larvae. Even though we had a lot of beetles laying eggs last fall, sometimes problems just don't transpire because of climatic conditions.”
Marlin Rice, Iowa State University


“The outlook for 2005 depends on the type of weather we have during the growing season. Hot, dry conditions would favor spider mite problems and cooler weather will favor soybean aphids.”
Phil Sloderbeck, Kansas State University


“The regional entomologists have looked at the trapping data. As a group we have predicted that there would be more soybean aphids in 2005 than in 2004. The aphid appears to be setting up a two-year cycle, so 2005 will be the year to test that prediction.”
Chris DiFonzo, Michigan State University


“Bean leaf beetles will always attack the earliest planted soybeans. Initial indications are that even with the open winter and the cold temperatures, bean leaf beetles are surviving.

“It'd be a safe bet that aphids are going to be worse. If we have droughtier conditions, and we don't see a lot of heavy spring rainfall, we could see a more severe outbreak. Watch what's being found in southeast Minnesota in late June and early July. If things are going well for the aphid there, it usually means there will be abundant aphids to colonize the rest of the state.

“We'll still see fairly low corn borer populations by next fall. Western corn rootworms will take a hit from the cold weather; Northern rootworms are a little more winter hardy. I would definitely scout for corn rootworms this year.”
Ken Ostlie, University of Minnesota


“For 2005 I expect more wireworm and white grub problems in corn and soybeans, although seed treatments for both crops may help reduce problems with these pests.

Grasshoppers will again be a problem in the northwest and southern areas of the state. We'll survey for Japanese beetles, western bean cutworms and burrower bug populations in soybeans and corn, although I expect only minor problems.

“With the high numbers of overwintering eggs being reported from Canada, most North Central states and even in Missouri, I am concerned we could receive high numbers of aphids when they migrate south during late July. We found very few pests or beneficial insects in late 2004, so beneficial populations will build slowly if a major pest does emerge in 2005.”
Wayne Bailey, University of Missouri


“In 2004 the top insects were soybean aphids on soybeans and western bean cutworms on corn. Western bean cutworms surprised a lot of people because they have been expanding their range, and there were questions about the expected degree of control in Bt corn hybrids.

In 2005 I expect we'll again see soybean aphids and western bean cutworms, but I also think we'll see higher rootworm pressure this year, given the winter weather to date.”
Robert Wright, University of Nebraska

North Dakota

“Soybean aphids were prevalent in southeastern counties, and some fields were above economic threshold levels in 2004. We will need to continue to scout for soybean aphids and European corn borers in 2005. Producers are also encouraged to use best pest management practices to reduce general insect pest pressures.”
Jan Knodel, North Dakota State University


“On corn, I don't see anything special becoming a major problem. The only exceptions are the few fields in western Ohio that will need treatment for corn rootworm on first-year corn. However, this should not be a widespread occurrence.

“In soybeans, based on all our observations, we are predicting that soybean aphids will again be a major problem in more northern areas, similar to 2001 and 2003.”
Ron Hammond, Ohio State University

South Dakota

“We've had heavy numbers of soybean aphids migrate into buckthorn plants to overwinter. That's why I think in 2005 we'll see soybean aphid infestations again in parts of South Dakota. North of I-90 we'll see bean leaf beetles on soybeans. Statewide, there will be infestations of corn borers. Western bean cutworm will also be a problem in the southeast part of the state. We will need to continue to scout for other insects.”
Mike Catangui, South Dakota State University


“If the pattern holds, based on Fall '04 suction trap captures of winged soybean aphids in Illinois, I wouldn't be surprised if 2005 is an aphid year. We're going to stress scouting. And, because of soybean rust, people should be doubly interested in watching their soybeans closely.

“A high adult population of corn rootworm in 2004 indicates the potential for large numbers of eggs. So there's a possibility for rootworm pressures to carryover in continuous cornfields. But that always depends on overwintering success of the eggs as well as weather conditions at hatch and after corn planting.

We'll continue to track the Variant western corn rootworm in first year corn. First year corn in southeast Wisconsin has been affected in 2003 and 2004. During late July through August 2005, scouting corn rootworm beetles in both continuous corn and soybeans will be important to guide management decisions at planting in 2006.”
Eileen Cullen, University of Wisconsin

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