Cotton – Southeast – Pests Stirring But No Big Issues Yet – AgFax

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Pam Caraway, Contributing Editor

Owen Taylor, Editor

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Here is this week’s issue of AgFax Southeast Cotton, sponsored by the Southern Cotton Team of Amvac Chemical Corporation.

OVERVIEW

Tarnished plant bug populations in cotton are higher than average in parts of the Southeast, and populations may build further and across a wider area. Aphid numbers also are building. It’s still a bit early to detect the aphid fungus.

Widespread rains this week broke a short dry spell across much of the region. The crops are responding to better soil moisture, plus the rains beat back some pests, like spider mites.

Lesser cornstalk borer is an issue in peanuts, and treatments are underway where needed.

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CROP REPORTS

Gary Swords, Swords Consulting, Arlington, Georgia

“We were starting a fairly early cotton crop for our area, but then we hit weather delays and now have a bunch of later-planted cotton, too. We are trying to push this crop to be as early as we can without pushing any hard insecticides. Avoiding hard chemicals now will help us down the road with whiteflies.

“Thrips pressure this year was probably the worst we have seen. Aphids are building now, plant bugs are showing up, plus we have spider mites. We made our initial herbicide sprays and put out nitrogen on the cotton. We are coming up to layby on most of our acres.

“In dryland peanuts, about 10% of the fields have high numbers of lesser cornstalk borer, with some extremely high. We are treating those fields this week. On the other hand, some fields don’t have any. We’re finding cutworms, too, but so far nothing over threshold. Our first fungicides are out on the oldest peanuts.

“Our first corn is at full dent now, and the bulk of the acreage will be at full dent next week. Our corn acres are up. Stink bugs are here, but they aren’t too heavy. I found some Southern rust early, but it didn’t explode on us as we expected three weeks ago when Tropical Storm Cristobal was coming toward us. We did have more Northern corn leaf blight than we’ve had in a couple of years. We probably treated about 70% of the corn with a fungicide.”

 

Dominic Reisig, NCSU Extension Specialist, Entomology, Plymouth, North Carolina

“In cotton, thrips pressure has been heavy. We expected that, given the forecast from the North Carolina Thrips Predictor Tool. I started here in 2009 and I’ve never seen thrips damage this bad. Contributing to the problem is that we have cotton that is just sitting there. First, we had the cooler temperatures. Now it’s warmed up, but we have saturated soils in places, so the plants aren’t growing. We should be well into squaring now, but for the most part plants have stalled out.

“Last year we were spraying plant bugs at this time. If I were a plant bug, I wouldn’t want to be in this cotton either. Since cotton is a sink for that insect, I expect plant bugs to show up in cotton once their wild hosts start drying down.

“For the first time in several years, we’re seeing kudzu bugs in soybean early in the season. People sprayed a few fields, but I don’t know whether any were at threshold. The treatments that went out were tankmixed with the last herbicide application. We had slugs in the early crop of soybean, but we expect them to be less of an issue in the double-cropped fields.

“In corn, we expected heavy stink bug pressure, but they didn’t really materialize.  Historically, we expect a generation to turn over in wheat and then move into corn. Over the last 10 to 15 years, we’ve seen a trend toward stink bug populations thriving in a corn/soybean rotation, rather than in wheat.

“Isolated cornfields are being sprayed for stink bugs this week. We are seeing Southern green stink bugs, which is unusual for us. We suspect that results from a series of mild winters. The good news is Southern greens are easier to kill.”

 

John D. Beasley, South Georgia Crop Services, Inc., Screven, Georgia

“We hope to find a bloom this week, but it might be next week. Temperatures were cool last week, which slowed down this crop. Most fields have good moisture. We treated a few fields for plant bugs, which is unusual. Numbers were higher than normal in corn, and we wondered whether that trend would continue in cotton. It did.

“In peanuts, we are seeing fairly high numbers of lesser corn stalk borers. We’ve started treating, although not a lot yet. But the way they look, we probably will spray a significant number of acres this year.

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“Corn is at the dent stage. We’re at least three weeks from any of it being mature. We treated most of the acres for Southern rust. I think we’re going to have some pretty good yields. We didn’t get as much sun as we’d like, but you can’t have rain and sunshine. We’ll take what we got.”

 

Michael Mulvaney, Cropping Systems Specialist, University of Florida, Western Panhandle

“We received a lot of rain when Tropical Storm Cristobal came through, then it turned pretty dry, and it just started raining again this week. Planting was on time for most of our cotton. We have a lot of young grasshoppers showing up, especially where we have residue.

“With all of the rain, many peanut growers are concerned that the gypsum moved out of the pegging zone. Growers who are concerned about whether to reapply gypsum should take a pegging zone sample. For a pegging zone test, sample 3 to 4 inches deep and then write “pegging zone” at the top of the form. The depth of the sample changes the recommendation. Apply gypsum as recommended after receiving the results. Start with fields that show less than 500 lbs calcium per acre in the pegging zone.

“In the Eastern Panhandle, we’re seeing some yellowing and rapid decline in corn, and that may be due to N and K leaching. However, with the crop at this late stage, there’s little we can do about it.

“We do have peanut seed quality issues. I saw a bag label that showed 60% germ. The lesson going into 2021 is to check the germ and set your seeding rate accordingly. We have to pay attention to the germ before we pour the seed into the hopper. It’s unfortunate that we have to do that, but it’s better than being forced to replant.”

 

Tyler Sandlin, Extension Crop Specialist, North Alabama, Belle Mina

“We turned the corner with our weather. The rain on Monday night (6/22) was particularly needed for our corn, which is at tassel.

“The cold, wet weather at planting delayed our cotton crop, so we’re a couple of weeks behind normal. The majority of the fields are just starting to square. A few plant bug sprays are going out. Our pressure isn’t as heavy as the Mississippi Delta, but plant bugs are a priority pest for us. We control them in most years with 2 to 2.5 sprays, although that can go up to 4 sprays in a heavy year.

“We are putting out N topdressing and sidedress  and mixing potassium into some of those applications. With the early-maturity, fast-fruiting cotton varieties that we plant, growers are seeing anecdotal yield increases from supplementing potassium granularly in-season. We don’t yet have the data to support that idea, but a lot of growers are pushing for high-yield crops so they’re pulling a lot out of the soil. From that standpoint, adding nutrition makes sense.

“We are 90%-plus finished with wheat harvest. Although we expected a poor crop due all of the fall and winter rain, we made a decent crop where the wheat was still standing. In places, yields have been exceptional.

“We are watching pigweed closely to determine whether control is slipping with dicamba. We have reports from opposite ends of the state that show poor control on weeds 2 inches or smaller. Auburn weed specialists are walking the fields and screening samples. Growers need to walk behind their treatments to ensure they’re getting good control.”

 

Jennifer Bearden, Extension Agricultural Agent, Okaloosa County, Florida

“In the aftermath of the six inches of rain Tropical Storm Cristobal dropped here, we are finding cotton seedling disease. We sampled to see which fungus is at fault.

“Grasshopper numbers still are higher than usual, but they’re waning. Plant bugs pressure is light so far.

“Our peanuts look fairly good, considering we are either feast or famine on rain. You would think it would take more of a toll, but the plants are holding up. We were a little worried about seed quality, but nothing is as bad as we feared, given what we were hearing earlier this season. We only have a few skippy stands. We are starting fungicide applications.

“Across the Florida Panhandle, we started a study regarding peanut collapse. The issue started in the Suwanee River Valley area where the study started last year. We expanded it across the Panhandle to look for differences between the areas that are experiencing it and those that aren’t. We don’t know whether it’s a virus, fungus, nematodes or a combination of all. We are sampling everything.”

 

Sally Taylor, Virginia Tech Extension Entomologist, Tidewater REC

“Stink bug pressure in corn has been light in most regions. Some fields will be affected and corn is susceptible to yield loss in the two weeks prior to tassel through R1. To speed up scouting, check the region of the developing ear and one leaf above and below. Stink bugs tend to prefer this area until reproductive stages of development.

“Most cotton and peanut fields are past thrips susceptibility. We will start scouting plant bugs when squares are on plants.

“In soybean, watch for defoliators and kudzu bugs. Soybean can recover from a good amount of defoliation and even multiple defoliation events. Defoliation thresholds up to two weeks prior to bloom are 30%. That’s a conservative threshold, and we want to focus on avoiding treatments in early season so we can preserve natural enemies. Early-season sprays contribute to repeated sprays later in the year.

“Kudzu bug has been spotted in many regions of Virginia by homeowners and farmers. This could indicate a problem for soybean producers. Until mid-July, soybean can tolerate up to 5 bugs per plant.”

 

Ron Smith, Extension Entomologist, Auburn University

“Tarnished plant bug adults are leaving the daisy fleabane and moving into our April-planted cotton in central Alabama. Some fields are already over damage threshold. Scout closely. We already have places that are below 70% square set.

“We are mostly finding plant bugs in the oldest-planted fields. By the time the later-planted cotton reaches pinhead square, they may be gone. If you have a sweep net, the threshold is 8 adults per 100 sweeps. If you don’t have a net, use 80% square retention as the threshold.

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“If you walk the field slowly early in the morning when the dew is present, you can confirm the adult plant bugs are in the field. They’ll be hanging around the terminals. If you treat with an insect growth regulator, don’t apply it until you find immatures in the field, which usually coincides with first bloom.

“We were in northeast Alabama last week and saw some quite heavy girdling from three-cornered alfalfa hopper. The damage appears as a small, stunted plant with a deep red stem with reddish leaves. Those plants eventually die. At this point, the damage is old and you can’t make a difference in the plant health by treating.”

 

Phillip Roberts, Extension Entomologist, Tifton, Georgia

“Scout for plant bugs and monitor square retention. Based on calls, this year’s plant bug pressure may be a little above normal. Some people are finding them, so we all need to look for them. Determine where you need to treat and get after them. They’re not here in terrible numbers, but plant bug populations may be a bit above normal this year.

“Aphid numbers started building rapidly this week. That’s normal. Whether to treat is a judgement call. With data from the University of Georgia, we can’t demonstrate a consistent yield response to spraying aphids.

“If aphids are inflicting stress, such as slowing the growth of your cotton, then you need to relieve that stress. We don’t want to slow down this late-planted cotton.

“A small percentage of our fields need aphid applications every year, but we have to make that decision on a field-by-field basis. We likely are 7 to 10 days away from seeing the fungus. To find the fungus, look for fuzzy grey aphid cadavers. Once we see those, aphids are likely to crash within a week.

“We’re finding whiteflies in our historical areas. Growers, scouts and consultants need to know they’re there. We are a long way from treating whiteflies, but we need to factor them in when making treatment decisions for other pests. With this whitefly situation, we need to preserve beneficial insects as much as possible.

“We could use a little shower. That’s the main thing. Overall, we’re off to a good start.”

 

Jeremy Greene, Clemson University Entomologist, Blackville, South Carolina

“In cotton, we are seeing more aphids. We easily collected winged aphids in some small, late-planted cotton. In the larger cotton, we are seeing strong aphid populations. We are watching for the virus but haven’t seen it yet.

“We started sampling for plant bugs today (6/23) in growers’ fields but haven’t found any at threshold yet. Historically, we reach threshold in only 10% to 20% of our fields. Growers aren’t used to battling that insect in our area, and with cotton prices so low, I don’t see us spending money to battle plant bugs. We will sample pre-bloom and post-bloom.

“Spider mite pressure remains low. Typically, the weather turns just dry enough to find them starting to build, then it rains again and beats them back.

“Some caterpillar pressure is building in non-Bt corn, but it is not heavy at this point. More stink bugs than expected are showing up in sweep samples in prebloom cotton that’s at 10 to 12 nodes.”

AgFax Southeast Cotton is published by AgFax Media LLC
Owen Taylor, Editorial Director.
 
Working-Copy%5B1%5D.jpgThis weekly report is distributed during the cotton production season. It is available to United States residents engaged in cotton farming, field scouting and other qualifying ag professions. Mailing address: 142 Westlake Drive, Brandon, MS 39047. Office: 601-992-9488.
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