As invading kudzu bugs spread, scientists and farmers plan counterattack

By Tom Hallman

Kudzu bugThe good news is, we can kill them.  

The bad news is, it'll cost us.  

And the damage they do in the meantime will cost even more.  

Kudzu bugs, first discovered northeast of Atlanta three years ago, have swept through Georgia and the Carolinas like Sherman. And like the notorious Yankee, the invading Asian insects wreak havoc wherever they go and remorselessly leave destruction in their wake -- especially to soybeans, a staple crop for farmers.  

"They've already become an economic pest on soybeans in the areas they've infected. They're fast-moving and can have a significant impact on a crop," said Jeremy Greene, a Clemson entomologist who is leading the charge to fight back. "Fortunately, we've learned a lot about them in a short time. It's important for us to assess what we know and formulate the best response for the future."  

For that reason, Greene hosted a national conference at Clemson's Edisto Research and Education Center in Blackville, S.C. this fall, drawing agricultural scientists and farmers alike to plan the counterattack.  

While crop pest experts intend an aggressive assault, no one is under the delusion it will be an easy fight.  

"The word 'eradication' is not being used with the kudzu bug," said Steve Cole, director of the plant industry department in Clemson's regulatory services division, which oversees efforts to monitor invasive species in South Carolina. "The best we can hope to do is find a suitable method of control."  

Mercifully, scientists have come up with insecticides, that kill swarms effectively, minimizing the damage the bugs cause to soybean harvests -- which tests show average more than 4 bushels an acre on a crop currently selling for about $17 per bushel.  

But the insects reproduce in such large numbers and move about so freely, timing pesticide sprays is a tricky business. If your timing is off, you may kill the bugs in one field only to have others swarm in from nearby.  

"It's the early infestations we're worried about now," Greene said. "We're studying them to get that application timing down just right."    

The kudzu bug -- so named for its affinity for the ubiquitous creeping vine that has enveloped much of the South -- is technically a bean plataspid, which is related to stink bugs. It can secrete a foul-smelling chemical that immediately identifies it. Some people are sensitive to the secretion, making it a medical problem as well as a homeowner nuisance and economic pest.  

The bean plataspid feeds on the juices of legumes, pod-bearing plants that include kudzu, soybeans, peanuts, alfalfa and clover, among others. Although the bug likes the taste of kudzu, it doesn't require it.  

"They don't have to build up on kudzu to move to soybeans. They can overwinter elsewhere and move directly to a bean crop," Roberts said. "That's why we have to get our timing and chemicals right. As long as the kudzu bug's migration is occurring, we can get a re-infestation."  

"They feed on the vascular fluid of the plant, primarily at the stems," said Clemson doctoral student Nick Seiter. "They're not actually feeding on the beans. They like the thick stems and they leave lesions you can easily see. These lesions put a great deal of stress on the plants and can lead to some pretty severe yield losses."  

Test plots at Edisto and Griffin, Ga., averaged an 18 percent yield reduction from the pests. Damage varied widely, though. Some fields were untouched; others lost as much as 50 percent of their yield as the plants set fewer pods with fewer, smaller beans.  

The kudzu bug has already caused an international incident -- one with ominous portent for American agricultural exports.  

"Honduras found seven dead kudzu bugs in a poultry shipment from Georgia. They stopped all agricultural shipments from Georgia, the Carolinas and Alabama for a time," said Joe Eger of Dow Agrosciences, one of the speakers at the Clemson conference. "Argentina and Brazil are big soybean producers. They are watching what we do carefully."  

Until longer-term solutions can be found, Extension agents are helping farmers face strike a balance between the cost and timing of insecticides.  

"Will yield increases offset the cost of the spray? That's the decision farmers will have to make," said Ron Smith, an entomologist at Auburn University. "With $17 (per bushel) prices, you'll see more sprays than at $7."  

"We can control them," Greene said. "It will take discipline. It will take patience. It will take more research to properly define what we're dealing with and how to respond."  

-30-  

Learn more about the kudzu bug:

http://www.clemson.edu/extension/kudzubugs/index.html  

View video and interviews about the kudzu bug:

http://www.clemson.edu/public/psatv/ag/soybean_plataspids.html  

More on pest management:

http://www.clemson.edu/extension/rowcrops/pest/index.html




For information: Jeremy Greene, 803-284-3343, ext. 245, greene4@clemson.edu