By David Bennett, Delta Farm Press
In the state of Arkansas, 2017 has been a year when redbanded stink bugs are gaining ground.
“They overwintered in crimson clover planted along roadsides and that’s a common cover crop plant, as well,” says Gus Lorenz, Arkansas Extension entomologist. “In March and April, we were sweeping and finding them in the clover, so we knew they could be problem.
“Redband overwintering here is not a common situation because it’s a subtropical pest. It usually moves in from Louisiana and Texas and gets here much later in the year. In the past, normally, only the southern tier of Arkansas counties has had to deal with it.”
Well, the pest overwintered as far north as Pine Bluff. “We know that because we sampled and found them.
“Sure enough, as the soybean crop has matured in the southeast part of the state, our growers have found they’ve hit threshold. A lot of growers have had to treat once or twice. A few acres have been treated even three times.
“The redbanded stink bug isn’t like the southern green (stink bug) or browns, it causes more damage, is a bit harder to control, and it bounces back from applications much quicker.”
Because it’s a tougher pest, instead of the threshold being nine per 25 sweeps — the common threshold for other stink bugs — the redbanded threshold is only four-to-six per 25 sweeps.
“So, there’s a lot of concern about redbanded stink bugs because we have a late crop in Arkansas and we know it’ll move — as the early-planted soybeans begin to dry down, they’ll push into late greener fields.
“There have been a lot of grower questions about how to manage the pest, when to terminate applications and the like. Based on the work that’s been done, they can feed into the pod much later than the normal, native stink bugs.”
The recommendation has been to control and spray redbanded stink bugs through R-7. “With our native species, we double the threshold at R-6 and walk away at R-6.5. You can’t do that with redbanded stink bugs because they cause a lot more damage, often later into the development of the plant than we’re accustomed to. So, we’re changing our strategy and trying to keep up with how it’s moving across the state.
“Redbanded stink bugs have an extremely high reproductive potential and can get up to alarming numbers in a short time. Applications in south Arkansas, in many circumstances, are only giving about 12 days of control, then the stink bugs are right back in the crop.
“We’re at a point in the season when many growers are tired of spending money and they’re running out of patience. They’re also beginning to harvest corn and rice is getting ready — their focus is on a lot of things. But if you don’t stay on top of redbanded stink bugs, it can mean a lot of trouble very quickly.”
Would a good, freezing winter knock them back?
“Absolutely. We had them back in 2009 when they crept up into the state after a couple of mild winters. Then, we had a hard winter and that knocked them back for four or five years. Last year, they started coming back into south Arkansas. Follow that up with the really mild winter we just had and that’s allowed this huge problem we’re having with redbanded stink bugs. A good, cold winter is exactly what the doctor would order as a prescription.”
What about fall armyworms?
“This has been one of the worst fall armyworm years we’ve had — and largely for the same reasons we’ve seen red-band stink bugs be an issue. The armyworms overwintered in the state, which they normally don’t. As a result, we had an excessive population starting out.
“A lot of pastures have been treated multiple times. We have them in rice at levels where they’ve defoliated some fields pretty severely. They’ve gotten into soybean fields — growers would let a little grass grow, then spray and that pushed them into the crop. That meant a lot of damage to some seedling beans. Now, we’re beginning to see fall armyworms in our cotton crop where they infest the lower bolls. It’s just been a busy year for fall armyworm.”
The situation with armyworms is all over the state, says Lorenz. “They’re all over the Arkansas River Valley. They’re bad all over — no place has missed the problem.”