Kudzu bugs are “spreading like wildfire” in parts of east-central Alabama, says Ron Smith, Auburn University Extension entomologist.

“Kudzu bug adults are attacking early planted soybeans in the Prattville, Tallassee and Auburn areas,” said Smith on June 19. “At present, our treatment threshold is five adults per plant.”

Smith says he’s afraid farmers may overlook immature kudzu bugs because they’re so small, and they tend to look like aphids.

“They’re in all but 13 counties in Alabama right now, and it appears to me they will be at economic levels in at least half of the counties before the season is over,” says Smith.

They’re not difficult to control, but knowing when to spray is really critical, he says. “Otherwise, we might end up making a lot more applications than are needed. The biggest key is detecting the presence of the immature stage. We’ve had immature kudzu bugs for a week or so on April-planted soybeans. They’re already there. Those beans will be the heaviest hit because kudzu bugs seem to pick out the earliest planted and oldest beans. In the Tennessee Valley, where most of the beans will be planted behind wheat, there will be a lot less risk,” he says.

Basically, all labeled pyrethroids give excellent control, says Smith.

The kudzu bug is about ¼ inch long and is light brown in color with an olive green hue and dark specks. Its life cycle normally takes from six to eight weeks, depending on the temperature. It overwinters as an adult and can survive very cold winters.

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.

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