2011 will forever be known as the year the kudzu bug invaded South Carolina soybean fields. Jeremy Greene, Extension entomologist with Clemson’s Edisto Research and Education Center near Blackville, South Carolina has been working in conjunction with scientist from Georgia gathering as much information as possible on the kudzu bug, it’s economic impact on soybeans, as well as control in future years:
“Basically, last year, 2011, was the first year that we had enough of this insect to conduct research on. And what we found, last year when we put all our trial work together, all the different trials that we did, the treatment threshold trials, insecticide efficacy trials and looked at yield, where we treated at least one time for this insect, compared to where we didn’t treat, we saw an average yield reduction of about 20% due to this insect.”
As far as what to expect for 2012, Greene says there was nothing this winter to knock the insect back:
“In fact, it may actually be worse than it was last year. In 2010 I didn’t have any of these insects…I only had a few insects on my research plots on the experiment station. 2011, we had ample numbers to do research on. So, all those insects went into overwintering and may just be completely inundated this year. Who knows?”
As far as control on the 2012 crop, Greene says that some preliminary data is promising:
“Basically, initiate treatment in soybeans when you see one immature, or one nymph per sweep net, using a sweep net. And then subsequent actions would probably include something like two bugs per sweep with a sweep net. So, that’s kind of our tentative recommendation at this point. We think that the immature stage is very critical if that stage is left to complete it’s generation on soybean, we think that there’s a high probability of yield loss.”
With regard to the growth stage of the crop, these observations were made in 2011, according to Greene:
“Most of the trials when used those insecticide applications and when they were timed based on crop finality, it looks like the R-3, or R-4 growth stage of soybeans, is the critical stage of growth, our tentative recommendations, I should say, do include that language, that applications targeting the immature stage at R-3 and R-4 at one nymph per sweep with a sweep net seem to be kind of the best strategy at this point until we can gather more information this season.”
Greene says that their data from 2011 didn’t indicate that spraying outside the field in neighboring hedgerows, or areas of kudzu would have any benefit:
“What we found is that when this insect settles in on a soybean crop, it pretty much stays there and it’s going to lay eggs, and its going to commit to that crop and there’s going to be just that one generation. So, we think from the limited information that we have from last year, the one insecticide application, well timed, can control a lot of that reproducing population.”
For pesticide recommendations, and application rates, Greene suggests contacting the county extension agent.
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