Alone, a soybean aphid can’t do much harm to anything.

Sunday, August 19, 2001

Alone, a soybean aphid can’t do much harm to anything. But when they descend on a soybean field by the millions, they can cause serious damage.

Now these tiny bugs from China are populating soybean fields in Freeborn County.

&uot;I didn’t see them last year, but I haven’t been in a field yet this year where I didn’t see quite a few,&uot; said Brian Jacobs, agronomist at the Alden Elevator. &uot;They’ve definitely spread into our area.&uot;

The soybean aphid appeared in the Midwest in force last summer, and southeastern Minnesota seems to be one of their favorite places, Jacobs said. But most farmers are taking a wait-and-see attitude as scientists try to measure the affects of the aphid infestation.

&uot;We really don’t know too much about them yet, or how they can affect yields,&uot; Jacobs said. &uot;We don’t even know if it’s cost effective to spray for them.&uot;

Soybean aphids are tiny translucent green insects that typically hide on the underside of soybean leaves, sometimes numbering up to 100 per leaf. They can cause significant reduction in growth and seed production. Aphids can also carry plant viruses deadly to soybeans.

Jacobs said scientists are trying to determine exactly what kind of threat the aphids pose as well as strategies to curb the infestations. Though many insecticide companies are suggesting chemicals such as Lorsban 4E, Furadan 4F, and Warrior, researchers are also looking for natural enemies like the common lady bug.

&uot;I think we’ll know a lot more about the aphids by next year. They arrived kind of late in the season this year, and might not affect the yields much,&uot; Jacobs said. &uot;But if they show up again in force next year, we need to know how to handle it.&uot;

For now, Jacobs is adding the aphids to a long list of pests that can threaten the soybean crop from year to year, including spider mites, and soybean cyst nematodes.

&uot;There’s a lot of elements besides weather that can hurt a soybean crop. Let’s hope the aphids aren’t around long enough to cause us more worries than we already have,&uot; he said.