Recent hot, dry weather has allowed pests to build populations and move into Arkansas row-crops.
“Right now, because of the hot, dry weather there’s a spider mite outbreak,” said Gus Lorenz, Extension entomologist for the University of Arkansas Division of Agriculture today. “That pest is in the cotton from one end of the state to the other.”
Lorenz is also seeing spider mites in soybeans and corn.
“This weather is conducive to mite problems and they’re certainly popping up. The good news is there are some miticides that have dropped in price. That is helping a bunch.”
In some fields it seems the spider mites are arriving hand-in-hand with plant bugs.
“Plant bugs are blowing up in cotton, which is moving into bloom. I suspect our plant bug numbers are quite a bit higher than in the last couple of years.”
Weeds on ditch banks and field ends are drying down because there’s been no rain. That’s pushing the plant bugs to leave wild hosts and move into crops.
“Corn is beginning to turn to brown silk — so they’re also leaving the corn and moving into cotton. We have seen a lot of situations, even in pre-bloom cotton, with high plant bug levels. Usually, we don’t see plant bug movement en masse until the cotton is blooming. That wasn’t the case this year, though. And with the weeds drying down, there’s an even bigger move into cotton.”
Lorenz and colleagues are seeing plant bug numbers increasing statewide. But “they’re especially bad in cotton fields that are beside corn or wild hosts next to a levee.
“Growers are resorting to tank-mixing products to achieve the level of control they need to keep square retention at 80 percent, or higher.
“If you’re scouting cotton, you need to be looking down into the plant. Look in the blooms for developing bollworms.”
As for budworms, “our moth trap counts are way up. Anyone with conventional cotton may need to treat with a product” that will control budworms. “You can’t go with a straight pyrethroid.”
Unfortunately, spider mites aren’t the only pests tormenting corn growers, said Lorenz.
“Southwestern corn borers are also in the corn. Really, the weather favors our caterpillar pests as well as mites. Trap catch numbers are extremely high with the southwestern corn borers. That isn’t a problem with Bt corn, obviously, but the refuge/conventional corn is another story. Growers in most areas are being advised to make an application to control corn borer.”
In late June, “we also had a bollworm flight. We’re kicking up a lot of moths in fields.”
Trap catches of bollworms doubled or tripled in many areas.
“There has been a big egg lay — mostly south of I-40. I think we’ll see that move north through the (week of July 5). The timing of this isn’t abnormal — we get a July 4 flight every year — but the size of it is larger than in recent years.”
A northern migration brought many moths to Arkansas earlier this spring, said Lorenz. The first generation of that migration is now showing up. Add those to “our own home-grown moths and you can understand why we’re experiencing moths and egg-lay over an extended period.”
Lorenz also warns that as soybeans begin to bloom bollworms are moving in. Many fields, particularly in the southern half of the state, are at treatment levels.
“Since May, a couple of generations of webworms have moved through soybeans. Where they’re a problem, they seem to prefer the smaller beans. That’s also true of fall armyworms.”
In both cases, “problems seem to be most prevalent where growers let some grass grow up in their small beans. When they spray Roundup to kill the grass, the worms just head to the beans — some causing severe defoliation.”