Arkansas farmers are finding an “inordinate amount” of stinkbugs in their wheat fields, says Gus Lorenz. Seen over the east half of the state, but particularly in the southeast quadrant, stinkbugs potentially mean trouble for summer row crops.
The stinkbug situation began surfacing in early April. Lorenz, an Arkansas Extension entomologist, got a couple of concerned calls and went out to look at the fields. Following those first field trips, the calls started trickling in, then came in a torrent.
“Now, I can't stay off the phone about this. We've tried to determine what impact the stinkbugs are causing on the wheat crop. But there's just not enough information available to make a determination on that. We do have some tests planned to see if there's any impact on the wheat. Specialists from other Southern states — Alabama and Georgia among them — that have chronic stinkbug problems have told us there have to be sky-high numbers to get any impact in the wheat,” says Lorenz.
While the wheat situation is troublesome, what has many farmers worried is what this potentially means for soybean and cotton crops. Over the last couple of years, farmers have started seeing more stinkbugs in their wheat, says Lorenz. “Prior to that, we only saw them occasionally and in much lower numbers. Because of that, I'm not surprised at seeing the stinkbugs in wheat. I am very surprised at the sheer numbers, though. Let's hope these wheat fields aren't acting as reservoirs and staging areas for a stinkbug march into cotton and soybeans.”
In most of the wheat fields, the predominant species showing up is the brown stinkbug. There are also some green stinkbugs, rice stinkbugs and a few predatory stinkbugs. But the brown is everywhere and gives Lorenz and colleagues pause.
“Except for the rice stinkbugs, these pests are seed-feeders. They like soybeans and cotton. We don't know what they're doing in the wheat — they showed up two weeks ago when the wheat didn't even have a head. What are they eating?”
And there's another concern: what products to use to control them. In the past, studies have indicated that brown stinkbugs are much harder to kill with the insecticides labeled for soybeans than the green stinkbugs are, says Lorenz.
“When you look at the products available for control of brown stinkbugs, there are three pyrethroids and methyl parathion. With the pyrethroids, control is 30 to 40 percent mortality so they aren't great.”
Last year, researchers found that methyl parathion has good mortality but extremely short residual effects — less than half a day. Growers who used methyl last year were right back at treatment levels — or, in many cases, well above treatment level — in just a few days.
“I've applied for a Section 24-C with EPA for a label with Orthene. But they don't want to give us the same 24-C that Texas, Louisiana and Mississippi already have. They won't allow any new uses for organophosphates.”
Lorenz's argument to EPA is that this isn't a new use — there's already established use for Orthene in states all around Arkansas. So far his arguments haven't worked.
The potential for a terrible stinkbug year is upon the state, says Lorenz. “I've yet to talk to a farmer who isn't going to plant soybeans because he's scared of the stinkbugs in his wheat. That doesn't mean it won't happen, though.
“We're trying to get the word out that farmers should go ahead and grow wheat and not worry about the stinkbugs. Until we run some tests, there's really nothing we can do — we can't be proactive. We've just got to wait and see what happens.”
This whole year is starting out odd, says Lorenz. Besides stinkbugs, there are other pests showing up in big populations.
“Tick numbers are outrageous because of the mild winter. We're in for a bad tick year. If you're working in timber or are walking in the woods, you need to take precautions. Ticks are carriers of Lyme disease and other sicknesses.”