As if they didn’t have enough problems with too much or, in some cases, too little rainfall, populations of sucking, piercing insects are now forcing treatment decisions producers would rather not be making at this stage.
The thing that’s concerning entomologists most right now is the statewide aphid population, says Gus Lorenz, Extension entomologist with the University of Arkansas. Aphid numbers continue to boom. Lorenz thinks it has a lot to do with Arkansas’ slow growing cotton crop.
“We’re still treating this crop for thrips!” he says. “It’s almost unbelievable to think that we’re still treating thrips in the later portion of June. That’s a perfect indication about how late the crop is.”
Many producers are using a broad-spectrum insecticide to treat thrips. That approach is knocking out beneficials and is a factor in why aphid numbers are so high.
“We’re in a cycle that benefits aphids right now. The aphid fungus will show up in a few weeks and hopefully it will take a bunch of them out before a whole lot of spraying is required.”
Plant bugs have also been bad.
“The biggest thing we need to do with this late, young crop is to maintain fruit set at around 80 percent. We don’t want to do anything to delay maturity. Everyone needs to tighten their thresholds a bit and keep as much fruit as possible.”
It’s a delicate balance, admits Lorenz.
“You don’t want to try and save everything, but you also want to protect the fruit that’s there. It’s damned-if-you-do or damned-if-you-don’t. If you keep too much fruit and it turns off hot and dry, the plants will pitch fruit like crazy. At the same time, we’ve got a late crop and need to retain the early fruit as best we can to keep from delaying the crop further.”
Having “put up” so many tobacco budworms last fall, Arkansas’ cotton fields have been remarkably free of the pest in recent weeks.
“Thankfully, following some really high catch numbers early, trap counts for tobacco budworms are down right now,” says Lorenz. “The south half of Arkansas is trap-catching very minimal numbers of budworms. We may face problems further on, but there’s a lull in the budworm action right now.”
Bollworms are another concern, Lorenz says. In the southern part of the state – “say Lincoln County on down” – producers have seen a spike in bollworm trap counts. Consultants are beginning to report white eggs in the fields associated with those high counts.
“I’ve been spending a lot of time around Pine Bluff for the last few days, so I’ve been kicking up my fair share of bollworm moths,” says Lorenz. “We’re in the early stages of this population so it’s difficult to say.”
In the last couple of days, several fields Lorenz has walked have been at or just below threshold already. He says there’s no indication the situation will get better.
“What we’ve got going for us is that the majority of the cotton is Bollgard. On top of that, most of the cotton isn’t blooming since we’ve got a very late crop. On pre-bloom cotton, Bollgard does a pretty good job on bollworms. It’s much better on bollworms pre-bloom than it is after.”
A large grape colaspis population is also causing Lorenz and colleagues concern in rice. More and more of the pests have been seen over the last couple of years.
“We’ve got a lot of rice that’s been dinged by this pest and now it’s starting to show up on soybeans.”
The larva of this tiny beetle lives in the soil and feeds on a plant’s roots. There are areas within some counties – Woodruff, St. Francis, Lee, Monroe and part of Prairie -- that have chronic problems with grape colaspis.
“We’re trying to come up with solutions facing those problems. Colaspis has always been around, but it seems to be getting worse.”
In samples pulled from around Hunter (just north of Brinkley in east central Arkansas) “very high populations” are being found in the soil. Physical symptoms of plants hosting the bugs are very similar to plants affected by cyst nematodes. Grape colaspis shows up more in fields repeatedly planted in soybeans or rice.
“The Icon seed treatment has done a good job of controlling colaspis,” says Lorenz.
“North of I-40, we’re in pretty good shape with corn borers. There’s not a bunch of activity in the fields I’ve looked at,” says Lorenz
While he’s aware that higher numbers of borers are being seen in Louisiana and the southern half of Arkansas, Lorenz isn’t terribly concerned over the pest thus far this season.
A recent, quick survey done over the areas of the state where there is normally corn borer pressure shows hot spots harboring the pests’ first generation, says William Johnson, Pioneer field sales agronomist. But since most corn was planted prior to April 10 that means farmers can look confidently to historical precedent.
“That precedent shows that the corn crop outruns the second borer generation before it can do much damage,” says Johnson. “The next flight is expected around July 10. By that point, ears should be developing and borers won’t be as large a concern.”