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Late-season insects infest Mid-South crops

Populations of normally late-season dry-weather pests continue to build in Arkansas and Mississippi fields. “With this drought, farmers already are under major stress, and I hate bothering them with something else,” said Gus Lorenz on June 28. “But they need to know what to look for. We've got some messy situations already.”

Spider mites are “tearing” soybeans up, said the Arkansas Extension entomologist. “It's bad already — early days with this problem — and we really don't even have a handle on how bad yet. We're just at the tip of the problem. I think we'd have many more reports if folks knew what they were seeing.

“It's amazing how bad this mite infestation is already. I don't think I've ever seen such a bad situation in the state. And the problems have started so early — mites are usually late-season pests that hit in mid-July and come on in August when it's very hot and dry. Since it's been hot and dry early, the mites have shown up early.”

Angus Catchot, Mississippi Extension entomologist, has much the same story to tell. “Spider mites are a huge problem in Mississippi. Numbers are building across the state. We have some serious infestations and have had for a while.”

Mite problems in Mississippi began in the central and south Delta regions when cotton was in the one-leaf to two-leaf stage. “That's very unusual for us — spider mites usually don't show up until late in the season. The problem has been getting worse since. We're extremely dry, and that's helped the mite numbers build. Mites have now moved into the north Delta, and we're also beginning to pick them up in the hills.”

Catchot said a lot of cotton has been treated three times for mites. A 24-C exemption for Zephyr was recently submitted to deal with the pest. Previously the product was allowed only west of the Mississippi River.

“We got that registration on Monday (June 29), so I expect it's going to be a treatment our growers will use. Even so, having to treat so much is hurting bottom lines. We're putting a lot of money into this crop and there's plenty of season left.”

Lorenz suspects many producers are seeing yellow spots in fields and understandably blaming them on dry weather, too much herbicide or nematodes.

“But often mites are guilty. In the last few days, I've walked fields mites have absolutely worn out. Some very bad situations exist in central Arkansas but they're all over the state.

“In a bean field near England, Ark., we found plants that had a minimum of 200 mites per leaf. There were so many, they were balled up on the edges. It was incredible.”

Having seen the same in Mississippi, Catchot is a believer. “It's happening here, too. In a few fields, mites are balling up on leaf tips. Unfortunately, there's nothing registered in Mississippi to deal with mites on soybeans. We may not spray any soybeans, but I'm working with the Bureau of Plant Industry to get a product approved. We need that backup, just in case.

Mites can “get in the pocket of a grower and chew his billfold up,” said Lorenz. “They're expensive to take care of. We've got a test field near Lepanto, Ark. The grower says he's already spent $36 per acre to control mites. Imagine having that expense on top of all other input costs.”

The good news, said Lorenz, is plant bug numbers are down significantly from the last couple of years. But, conditioned to treat for the pest, some producers continue to spray for plant bugs.

“That's not helping. In fact, it can flare mite numbers. I'm very concerned that's happened.”

In traditional plant bug hotspots, Lorenz said, there is a little plant bug activity. But, on the whole, plant bug numbers are lower than they've been in years.

“We need to quit treating for non-existent plant bugs and concentrate on the pests really hurting our crops.

“Now, we've got beet armyworms in our cotton. Again, this is usually a late-season pest. But we're already at treatment levels for beet armyworms in Mississippi County and Ashley County. Since we have so much cotton around there, there's certainly potential for a big problem. And some of the fields being treated are Bt.”

Beet armyworms are moving into Mississippi as well. “We're beginning to flush moths and pick up egg masses in a few places,” said Catchot.

“We're also seeing unusually high numbers of potato leaf hoppers throughout Mississippi. We're generally not treating for them, especially once beans hit R-3/R-4. But they hit some varieties hard because the plants are extremely stunted by this dry weather.”

Another late-season pest showing up in Arkansas is the saltwater caterpillar. While not yet at treatment levels, “they're coming on,” said Lorenz.

He and his colleagues also have taken many calls regarding “grasshoppers problems all over the state. They're hitting soybeans and are feeding on milo. They're building in numbers and they're hard to control once they get bigger.”

Driving around the state, Lorenz sees “pitiful crops everywhere. Even the corners on center pivot fields are in bad shape. It's especially bad in Mississippi County, Crittenden County — really most of northeast Arkansas. If they don't get a rain there very quickly, I fear the consequences. The crops can't stand much more without water.”

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