Some soybean producers in Alabama were seeing kudzu bugs in almost plague proportions in late June.

This year’s infestation of kudzu bugs on early planted soybeans in Alabama could be a preview of what’s to come, says Tim Reed, Auburn University Extension entomologist. “Kudzu bugs likely will be our most serious pest of soybeans, possibly beginning next year on a statewide basis,” says Reed.

“We started to pick these up this year on seedling soybeans that were less than 1 foot tall,” he adds. “The ‘guesstimated’ threshold we’re using now until we get more data is five per plant. From 1 to 2 feet tall, on vegetative beans, it’s 10 per plant. And then once the beans are 2 feet tall, we’re hoping you can wait until you see immatures along with adults before you spray.”

Kudzu bugs apparently came straight from over-wintering sites and didn’t stop at kudzu at the Auburn University site, says Reed.

“The immatures look a lot like aphids. Going into this year, we were hoping we could avoid spraying kudzu bugs on seedling soybeans, but we’re not going to be able to do that. We’ve had reports from all over the state about kudzu bugs on seedling soybeans, and basically we’ve thrown out some of what we thought we had learned about this pest, as of the end of last year. It’s behaving differently this year,” he says.

Kudzu bugs were found in 15 Alabama counties in June of 2012. Now, there are only 13 counties where they haven’t been found, says Reed.

“They’re likely in every county in the state, and by this time next year, I expect them to be in all early planted soybean fields. We hope they will be a serious problem only in early planted soybeans. That has been the trend in Georgia and South Carolina.”

They’re primarily found on the main stem, though adults will be on the leaves, he says.

“If they’re in seedling soybeans now, you’ll probably have to make at least two applications to get you through the year. That’ll open you up to worm problems. We’ll have to see how this plays out in 2013.”

According to the Alabama IPM Guide for soybeans, kudzu bug numbers tend to be much higher on full-season soybeans than in later planted fields. Immatures normally appear in full-season soybeans in late July to early August. Kudzu bug adults and nymphs feed on the main stem and leaf petioles with sucking mouthparts. The kudzu bug’s feeding can reduce the number of pods per plant, number of seeds per pod, and seed size. This insect has been found to cause significant yield losses in Georgia and South Carolina soybeans.