What is in this article?:
- New pests complicating soybean insect control
- Spreading rapidly
• As a result of the short learning curve, researchers and growers alike are being forced to make some of the rules for management brown marmorated stink bugs and kudzu bugs on the run.
KUDZU BUGS on soybeans in South Carolina.
Herbert says this year, his research team has already documented BMSB populations in 20 Virginia counties and the number is almost certain to go up. He contends by the end of the year there will be many more soybean fields reporting BMSB populations than last year.
The Virginia Tech IPM leader says in some cases BMSB are following the same pattern of infesting only the edges of soybean fields. “Many growers are treating field edges this year and we are going to follow as many as possible to determine if those treatments worked and held,” he adds.
“The good news is that based on our insecticide trials it is not difficult to kill BMSB with several common insecticide products. And, many fields, especially the full-season crop fields, are rapidly approaching the safe stage, which based on previous field cage studies happens after R6 (full seed) when pod walls begin to toughen,” he explains.
Kudzu bugs are beginning to become more frequent pests of crops in Virginia, too. This Asian import, entomologists contend is most likely from Japan, is moving rapidly from south to north.
Since it was first confirmed in the U.S. in north Georgia in October of 2009, kudzu bugs have infested every county in North Carolina and South Carolina and are rapidly getting established in southern Virginia.
North Carolina State University Entomologist Dominic Reisig says in general this year many acres in his state were treated for kudzu bugs that didn’t need to be treated.
For sure, kudzu bugs can damage soybeans. In untreated tests we’ve seen up to 50 percent yield loss, but averaged nearly 20 percent across untreated soybeans, he says.
In South Carolina, Clemson Entomologist Jeremy Greene says soybean yield losses of up to 20 percent in untreated fields were seen last year.
This year farmers seem to be keeping a careful watch out for these pests and monitoring various information sources to stay ahead of these bugs, he adds.
There is a website dedicated to kudzu bug monitoring and management (www.kudzubug.org) that has an easy to use population threshold that can be used to determine when to spray. It also has timely updates on movement of kudzu bugs, insecticide control, identification photos and other tips for managing this new pest.
“Kudzu bug is so new and so potentially damaging to crops that growers just don’t know what to do. I had one agent tell me that one of his growers found one adult kudzu bug in a field, and he sprayed the field. That’s one end of the extreme and the other is waiting too late to manage populations of these bugs,” Reisig says.
Virginia soybean growers are caught in the middle of the north to south migration of BMSB and the south to north migration of kudzu bugs.
The increase in soybean acreage and the high price of beans ups the ante on developing economically sound management strategies for controlling these pests.
Neither of the Asian imports appears to be difficult to kill with a number of insecticides.
With BMSB, it is difficult to get accurate threshold numbers because of this insect’s amazing startle reaction. Herbert says sweep nets are still the best option, though sometimes standing in a field and slowly turning 360 degrees and counting the number of bugs you can see works about as well.
Kudzu bugs are likewise not difficult to kill, but when they get into soybeans with heavy foliage, getting the insecticide to the insect can be challenging, because these bugs feed on the underside of leaves and on stems of soybeans.
Scout late season soybeans, then scout them again and again seems to be the universal advice of entomologists across the Southeast as growers struggle to take optimum advantage of this year’s high prices.