Kudzu Bug Showing Up Early in South Carolina Soybean Fields

The kudzu bug munching on soybeans has only been in South Carolina a couple of years, and Dr. Jeremy Greene, associate professor of entomology with the Edisto Research & Education Center near Blackville, SC, says they’re still learning about this pest. This year, kudzu bug got an early start on young, vegetative soybean plants:

“We don’t know. I’ve got some test plots where we’ve sprayed some of these vegetative-stage beans that were completely infested and good mortality of the bugs, most of what we’ve been seeing on the vegetative stage beans up to this point have been over wintered adults, this insect overwinters in the adult stage, and came out of it’s overwintering sites looking for hosts. It found vegetative early planted soybeans this year, and it set up shop there. Those things are dying off at a rapid pace right now, very easy to kill with insecticides, but the next flush of adults will probably be the F-1 generation out of wild hosts like kudzu, and they’ll be a little more robust, and little hungrier.”

Greene says that he’s heard through the grapevine of producers looking at other crops so as not to have to deal with the kudzu bug on soybeans:

“Well, I’ve heard that folks are hesitant to even plant soybeans because of this pest. This is certainly a pest that we can manage with insecticides, and we can probably do it without it being dedicated trips for this insect, well, I would have said that before we had these infestations in early-planted soybeans which is still something that we’ve got to answer. But, we should be spraying our soybeans at times for foliar diseases, corn ear worms and stink bugs and we can probably mitigate most losses with trips across the field that we should be doing anyhow. So, I hat to hear that folks have thought about not planting soybeans because of this insect because we can manage it.”

With that being said, management is the key, not related to ignoring:

“Last year we saw a range of zero to 47 percent yield loss, when we averaged all our trials it was a 20 percent yield loss, which is significant.”
As far as quality loss, Greene says it’s different, yet similar to stink bugs:

“these things don’t feed on the seed, so you don’t see the typical quality loss like you see with stink bug feeding, they just feed on the stems. But, there are reduced seed weights and test weights, so I think quality is something that we need to look at, they can certainly hurt yield. They can reduce the number of pods per plant, the number of seed per pod, the weight per seed, things like that, that’s already been documented.”

As far as control, Greene says that pyrethroids are still the choice:

“The pyrethroids are pretty broad spectrum, they’re pretty harsh, on a wide range of arthropods in the field, and they do persist and provide some pretty good residual control. But, yeah, that’s a commonly used class of insecticide chemistry in soybeans, and it does a fine job controlling kudzu bug, there’s just some subtle differences among those chemicals. But, we have plenty of chemicals that will control kudzu bug in soybean.”

Dr. Jeremy Greene with the Edisto Research & Education Center near Blackville, South Carolina.

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