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Southern Grain Focus: Worms Still Hitting Soybeans, Milo – AgFax

August 30, 2015August 30, 2015
By Ernst Undesser and Owen Taylor

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Soybean looper on leaf. Photo: University of Tennessee

Southern Grain Focus:

Worms Still Hitting Soybeans, Milo

Owen Taylor, Editorial Director | Ernst Undesser, Web Editor

Worm treatments continue in soybeans and also in some grain sorghum. The list includes soybean loopers, bollworms, green cloverworms, velvetbean caterpillars and armyworms, among others. Stink bugs are around and are being sprayed in places, mostly when people treat for worms.

This has clearly been a “looper year” in a wide part of the South, and the activity and potential damage aren’t over yet.

Soybean loopers are a particular threat because they develop inside the canopy and aren’t readily seen if people aren’t closely scouting in soybeans. Also, they pack a good deal of resistance to pyrethroids, so higher priced insecticides are the main option. The insect came as much as six weeks earlier than usual and has ranged farther north than it’s typically found in both the Southeast and Delta states.

Tough decisions are having to be made about whether to treat in beans approaching maturity, especially as far as loopers go.

In grain sorghum (milo), headworms also are at treatment levels in many late-planted fields. Worms aren’t unusual in late milo, but the approach to dealing with them has changed dramatically in the last couple of years due to sugarcane aphids (SCA). In the past, cheap pyrethroid treatments would have taken out most worms. But with SCA in the picture, pyrethroids are on the “don’t use” list because they will eliminate beneficial insects and give aphids a bigger opening to develop.

Here are the latest updates from our most recent issue of AgFax Southern Grain.

Lance Honeycutt, Sanders, Inc., Jonesboro, Arkansas: “We treated about 80% of our soybeans for corn earworms over the last two weeks.”

Gary Swords, Swords Consulting, Arlington, Georgia: “In dryland soybeans we’ve been fighting loopers. We’ve had some control issues. Certain products worked better than others. Ground applications have given better results. Several guys with older beans have really had a fight on their hands. Looper counts hit 15 to 20 per row foot and treatments missed some of them.

“In some early planted grain sorghum we made it through with just a couple of insect sprays. Otherwise, insects have been horrible. We’ve been dealing with fall armyworms in heads in older fields and in whorls in younger grain sorghum. Where we’ve been dealing with worms in the head, it’s been intense in some cases and one grower had to spray every few days.”

Angus Catchot, Mississippi Extension Entomologist: “A lot of loopers are showing up in soybeans. For the most part, people are taking care of them. Folks are dealing with bollworms in a few late beans that were planted extremely late. With loopers, remember that it takes a good deal more defoliation to cause significant yield loss once beans are at R6. At that point you would need 60% across the whole plant to cause just a 10% yield drop. By R6.5 we terminate all caterpillar sprays, anyway, and it only takes about 7 days to move from R6 to R6.5.

“So, if you do not already have appreciable defoliation, don’t spray small loopers in R6 beans. In a week’s time those loopers won’t cause enough defoliation to matter. By R6.5 you’ll be past the point that they matter, anyway. That said, loopers could still have time to affect yields in beans younger than R6, so those could require protection.”

David Butcher, NC Ag Service, Inc., Pantego, North Carolina: “Most of our soybeans are starting to flower and pod, even doublecrop fields. We’ve mostly sprayed once for worms, although nothing was really bad. Mainly, we’ve been finding green cloverworms or corn earworms or both. Some loopers are around, too. In the past, people would try to go with a pyrethroid the first time, but that’s gotten somewhat inconsistent, maybe 70% control. Growers may still include a pyrethroid but will tankmix it with a newer chemistries for loopers.”

Lee Rogers, Rogers Entomological Service, Steele, Missouri: “We’re finding either stink bugs or loopers in soybeans, although in some fields we have both and in other fields we have nothing. In places, the only application has been a fungicide. With loopers, we’re going with higher priced materials if they’re bad enough and in some fields we have thresholds of both loopers and stink bugs.”

Brad Smith, Crop Production Services, Selma, Alabama: “In soybeans we’re picking up quite a few loopers, velvetbean caterpillars (VBC) and green cloverworms, and we’re spraying the majority of our beans. Loopers have developed in some fields that were far enough along in maturity that I was surprised to find them there. Where soybeans haven’t lapped, the majority of worms have been VBC.”

Luke Johnson, Johnson Scouting LLC, Donalsonville, Georgia: “We’re irrigating ultra-late beans – and very regularly, too. It’s hot and dry, plus they were planted thick. Those beans are using water quickly. The weather has been pretty good for developing a dense canopy. Loopers and armyworms have been high in places, so Dimilin has been very helpful on those species.”

Gus Lorenz, Arkansas Extension IPM Specialist: “This bollworm flight is one of the biggest in several years. It hasn’t been uncommon to pick up 40 to 50 worms in 25 sweeps in some late-planted beans. In certain untreated checks in our plots they’ve run 70 in 10 sweeps. Loopers are still coming in, too, and causing defoliation in places.

“We also have a smattering of green cloverworms, saltmarsh caterpillars and other pests. But the big story is the bollworm. They’re feeding on pods and also causing a lot of defoliation. People who maybe treated worms three weeks ago with a diamide are making a second application now on a lot of ground for some complex of worms. Moth counts are up a little more, so we’ll have consistent pressure as this crop finishes out.”

Steve Schutz, Ind. Consultant, Coushatta, Louisiana: “We had a big looper deal earlier, then they sort of crashed. Maybe the cooler weather affected them. In one field they took out 40% to 50% of the leaves, but beans were at R6. On the other hand, velvetbean caterpillars (VBC) have become our main point of focus, and I’ve treated a couple of fields exclusively for VBC.”

Larry Walker, Walker Cotton Technical Services, Flintville, Tennessee: “Soybean loopers have shown up in soybeans in the Tennessee Valley, so we’ll have to use a product like Interpid or Steward. Rains this past week totaled more than 4 inches. Our doublecrop beans have good yield potential and will need to be protected. These defoliators seem to be attracted to beans that are at half-pod fill, something between R5 and R6.”

Bob Griffin, Griffin Ag Consulting, Jonesboro, Arkansas: “We’ve been treating a few younger, unlapped soybeans for bollworms and/or armyworms. In older beans, 75% to 80% haven’t been treated for insects at all.”

Joe Townsend, Ind. Consultant, Coahoma, Mississippi: “Some soybeans have been harvested and a lot of the rest are close, aside from wheat beans. Big numbers of loopers developed and we’re seeing them in some soybeans that are far enough along that we wouldn’t have thought they’d be attractive.”

Ron Smith, Alabama Extension Entomologist: “Worms are rebuilding in a small number of soybean fields that were treated three weeks ago for worms. We’re finding velvetbean caterpillars, loopers and green cloverworms (GCW). Also, stink bugs are picking up big time in at least some soybeans. At Prattville in some plots we’re finding worms and green, brown and brown marmorated stink bugs.

“Moth trap counts for bollworms and budworms went up Saturday through Monday (8/22-24) in central Alabama, which would be significant for soybeans and grain sorghum. Hundreds of acres of soybeans in the Tennessee Valley have been sprayed in the last week, mostly for loopers and GCW. In fact, people are reporting tremendous numbers of GCW, with up to 30% defoliation in places. Enough soybean loopers are in the mix that people don’t want to risk using a pyrethroid.”

David Hydrick, Hydrick’s Crop Consulting, Inc., Jonesboro, Arkansas: “We’ve been treating worms in soybeans for three weeks. We’re dealing with loopers in older beans and bollworms and loopers in the younger fields. Stink bugs are out there, too. In one of the last fields I checked today (8/24) I averaged 7 worms in 10 sweeps.

“Treating has been a challenge. We keep getting rain, which has either washed off materials in some cases or delayed spraying. It’s a nightmare. Some products are performing better than others. No failures, but we’ve had less-than-adquate results at times.”

Jeremy Greene, Clemson University Cotton Entomologist, Blackville, South Carolina: “Bollworm pressure is still pretty high, based on moth trap counts here and what we’re seeing in the field. However, that may be a localized effect. At least at this location, trap counts will be higher this week than last week. Tobacco budworm moth numbers are up, too, and we see a lot of those moths flying around. Loopers seem to be cycling out. But we are finding small caterpillers in our plots, so another batch may be developing.”

Hank Jones, C&J Ag Consulting, Pioneer, Louisiana: “Where beans are still green, we’re kind of battling loopers and have made a second shot in places. They came in earlier than usual and are beginning to rev up again. Redbanded stink bugs have moved back in, as well. By the end of next week we’ll probably wrap up the bulk of soybean spraying and we may have one watering left on late beans.”

Phillip Roberts, Extension Entomologist, Tifton, Georgia: “You can find loopers or velvetbean caterpillars to some degree in soybeans, depending on the location. When you find worms, correctly identify them since you won’t have much effect on loopers with a pyrethroid. Soybean loopers will drive your insecticide selection at this point.”

Ty Edwards, Edwards Ag Consulting, LLC, Water Valley, Mississippi: “We have a large clump of later planted beans, and we’ll be fighting insects in those fields for a while. Most treatments have been with a residual larvicide. Depending on the situation in earlier fields, we sprayed once for bollworms and once for loopers.”

Dominic Reisig, NCSU Extension Specialist, Entomology, Plymouth, North Carolina: “People are making corn earworm treatments in soybeans but to some degree they’re cycling out. However, we’re looking at a new crop of loopers. We picked up a lot of moths over the weekend (8/22-23) and a couple of consultants said early this week that they’re finding small larvae in beans.”

Sebe Brown, Northeast Louisiana Region Extension Entomologist: “Soybean loopers are still hanging around in soybeans and redbanded stink bugs remain a factor. Treatments have been going out for both. More desiccants went out this week in beans.

“Headworms are still active in grain sorghum. That includes fall armyworms, bollworms and sorghum webworms. People also are reporting a fair amount of bird damage, mainly on field edges.”

Curt Johnson, CRC Ag Consulting, LLC, Lake Village, Arkansas: “We’ve had to go after loopers and bean leaf beetles in beans that were at about R5.5.”

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