The soybean cyst nematode can do damage to fields.

A very small insect is causing big trouble in Iowa’s soybean fields and it’s spreading quickly across the continent.

The soybean cyst nematode or SCN is being tracked in a survey throughout the United States and Canada every few years. SCN Coalition co-leader and Iowa State University Extension plant pathologist Greg Tylka says the destructive bug has traveled far since 2017.

“There are 55 new counties with SCN in 11 different states in the U.S.,” Tylka says, “and then also they found SCN in a bunch of new counties in Quebec, Ontario and Manitoba.” As odd as it may sound, he says the most common way they believe the tiny bugs are being transported from field to field and from farm to farm is by the wind, specifically in blowing dirt.

“The SCN female, which fills up with a couple of hundred eggs and eventually dies — a dead female full of eggs is called a cyst — that cyst is about the size of a period at the end of a printed sentence in a book or in the newspaper,” Tylka says. “It’s tiny and it very easily can be in soil particles that are blown.”

The soybean cyst nematode causes a lot of costly damage. “Even a moderately low level of SCN is probably going to take two-to-five bushels per acre out of the yield,” Tylka says. “We have scenarios in Iowa where we’ve documented 22-to-25 bushels per acre yield loss. There is a lot of money being left in the field due to the SCN.”

Tylka says another reason there’s been more detection of SCN is that his coalition is encouraging producers to do more sample testing. He says one way to get a handle on the insect is by properly rotating crops.

(By Jerry Oster, WNAX, Yankton/UNL photo)