Cotton – Southeast – More Pests Brewing, Pushed Along By Dry Conditions – AgFax

Cotton insecticide spraying. ©Debra L Ferguson

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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

Moisture is the differentiator. Crops are suffering in the many dry spots across the region – both from lack of moisture and pests that thrive in hot, dry conditions.

Whiteflies are spreading outside their traditional areas in Georgia. Scouting is essential to ensure timely control.

Stinkbugs lead the pest pack across portions of the region. Be aware of the dynamic threshold and treat accordingly.

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CROP REPORTS

John Burleson, Consultant, Swan Quarter, North Carolina

“We’re pretty dry now. Most of the cotton I’m scouting is between the second and fourth week of bloom. We’re probably two to three weeks behind our normal schedule and may be a little below average on yield, but the crop is looking better. We still have time to make a crop, but the late start cost us a lot of yield potential.

“Plant bugs are the primary pest right now, but they aren’t heavy. We are treating proactively because we have a later crop.

“We are at the beginning of a moth flight. We’re scouting for bollworm, but we hope we don’t need to make a treatment. We want to wait until about the fifth week of bloom when we need to clean up the fields and protect those bolls. Right now, we don’t have a lot of bolls to protect.

“We are about three weeks from corn harvest. Plants probably dumped a lot of bushels in the last three weeks because we haven’t had any rain.

“In soybeans, we’re about two weeks from any worm issues because beans were planted late. We don’t see many stinkbugs in soybean yet, either.

 

Brandon Phillips, Phillips Ag Services, LLC, Fitzgerald, Georgia

“The rain that fell Saturday (7/25) was the first we’d had in 25 days. Some small pockets received rain before that, but that was the first general rain in a while. Everything that we can put water on looks really good, and we have one of our better irrigated cotton crops. I would compare it to last year, which was great. Irrigated peanuts look good, too.

“We are fighting spider mites on a small percentage of cotton acreage. Plant bugs are going out and whiteflies are coming in. In a few pockets east of us, farmers had to spray for whiteflies. We are still primarily seeing whiteflies only where we normally see them. So far, reproduction is low and they’re at the bottom of the plant.

“We’re hoping whiteflies don’t take off because treatment costs for whiteflies doesn’t sync with 61-cent cotton. Two or three days of rain would help us tremendously with whiteflies and spider mites.

“We are in the middle of a corn earworm flight, and at this time the two-gene Bt technology is holding up well. We haven’t treated a cotton field for bollworms, although we may have incidentally caught some escapes when we sprayed for stinkbugs.

“Stinkbug pressure seems lighter, but that might not hold. So far, we sprayed about 40% of our cotton acres for stinkbugs. We’re harvesting corn now, and stinkbugs will move from corn to cotton and peanuts. They are insignificant in peanuts, but we need to protect our cotton bolls.

“In peanuts, the main concern right now is tomato spotted wilt virus. The virus is running hand in hand with the issues we had gaining a stand. At every skip you’ll see an infected plant, if not two or three infected plants. Timely fungicide applications are keeping the major peanut diseases under control. Most peanuts are at about 75 days. The second fungicide application is out on most of our acres. Some are moving into the third application.

“We are in a velvetbean moth flight. Once we start seeing them, we will pick up worms in 7 to 10 days, and a number of people proactively applied a residual worm treatment.

“We aren’t seeing spider mites in peanuts, which is unusual since we’re seeing spider mites in cotton. But the spider mites in cotton may be self-inflicted with all of the thrips and plant bug issues we had.

“Corn harvest started last week, and early irrigated yield reports are between 210 and 250 bu/acre. That’s a pretty good corn average, but we’re still on the front end of harvest. We’ll see how it looks after we bring in the rest.”

 

Jeremy Greene, Clemson University Entomologist, Blackville, South Carolina

“We have caterpillars and stinkbugs. With bollworm, we see stairsteps of injury. Damage in non-Bt cotton is quite noticeable, depending on planting date. We’re finding some injury in fields planted to two-gene cotton varieties, but we haven’t found much injury in three-gene cotton. So far, we haven’t found any fields that worry us, but populations are heading in a direction that has us recommending folks pay attention in two-gene cotton.

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“The majority of our cotton is in stinkbug territory – third to fifth week of bloom when we have heightened boll susceptibility. Check bolls for internal injury and follow the dynamic threshold, which should be familiar to everybody now. This is when we have the most bolls that could be injured, so we have the greatest risk to yield impacts from stinkbugs.

“When making a treatment decision, consider which pests are a problem and whether you can make one treatment that will control more than one of them. We have options that control stinkbugs and might have some effect on spider mites.

“In our area, a pyrethroid can still control escaped bollworm and could be used in fields with low worm populations. If bollworms are at threshold, we might need to make a different treatment decision. What you chose depends on whether the treatment is focused on stinkbugs or bollworm.

“For 9 out of 10 of our fields, the priority likely is stinkbugs. Stinkbugs are the No. 1 pest of cotton in South Carolina and much of the Southeast. But, scout closely where you have a history of bollworm problems.

“Spider mites are becoming more noticeable. Aphids are gone, but we have scattered signs of cotton leafroll dwarf virus. We can’t do anything to control it – and likely don’t need to do anything. We are still learning about this virus. With scattered and light symptoms, we aren’t likely to see broad yield reductions.

“In soybeans, I checked a field today (7/28/20) that is at R3 and it’s loaded with bugs and caterpillars – kudzu bugs, stinkbugs, podworm, soybean looper, velvet bean caterpillar and green clover worm. Defoliation is starting to increase quickly. So, we know insects are in the system. Scout closely to determine where they are a problem. Tailor your treatments to the populations you find. We don’t need to treat every acre the same.”

  

Sally Taylor, Virginia Tech Extension Entomologist, Tidewater REC

“Hopefully, everyone is receiving the rain that they need. Spider mites are still a concern and we should avoid flaring them. Remember that mites can be present and not cause losses. We can avoid needing miticides by being conservative with insecticides. Plant bugs are spotty across the region, between neighboring fields, and even within fields. Base spray decisions on what you find in your fields.

“My program is available to help if you have scouting questions and concerns. Do not hesitate to reach out to us.

“Our bollworm flight is picking up this week and we likely will see our trap catches increase over this week and next. Preventive sprays in two-gene cotton are recommended when 25% of terminals and/or leaves next to blooms have eggs. The highest percentage my team has found this week is 3%.

“Be conservative when planning sprays. Growers have several options for worm control in cotton, peanuts and soybeans. Consider whether you have eggs or worms when you decide which product to use. If you are unsure which product performs best in your field situation, or need to confirm which products offer residual control, contact me, your local ANR agent, crop consultant, or chemical sales provider.

“Cotton leafroll dwarf virus (CLRDV) has been detected in Virginia. Please reach out to us at the Tidewater station if you observe unusual plant growth not explained by herbicide injury or drought stress and/or you found aphids in your field. You cannot control the virus by spraying aphids.

“Also, I don’t think there is any reason to be concerned over yield loss until we know more about the virus and what causes its symptoms.”

  

Ron Smith, Extension Entomologist, Auburn University

“Overall, insects are quiet in Alabama. We are finding low levels of aphids in many fields, and a few tarnished and clouded plant bugs are present in nearly every field. But we haven’t seen any at treatable levels recently. Spider mites are in a number of fields, and the longer we stay dry, the worse mites will get.

“Stinkbug pressure varies from field to field, but they are quietly building. Two issues influence stinkbug populations: proximity to corn or peanuts and the size of the field. Populations will be higher close to corn or peanut fields. They move out of corn when it dries down. Although stinkbugs don’t harm peanuts, they move to cotton from peanuts all season long.

“Field size influences populations because stinkbugs don’t fly well. So in fields that are 75 acres or larger, it takes a long time for them to hit threshold. Ideally, we could make border sprays. However, that approach isn’t practical for many growers who have large fields spread across a wide area.

“We haven’t had any bollworm calls on 2-gene cotton. If we look long enough, we can find an escaped worm. However, they’re at a very low level and in both central and south Alabama we are already past the moth flight out of corn. Since we are past the flight and we still don’t have many escaped worms, it looks like it’s going to be a light bollworm year.

“The pest we are most concerned about going forward is the silverleaf whitefly. We don’t think we have any fields infested yet, but we are checking likely areas again on Thursday (7/30).

“Where we have moisture, cotton is adding a lot of fruit. We really would like to have a rain over most of the state this week.”

 

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

“Some places received recent rains, but we still have dry spots. Some of this corn looks absolutely burned up. We’re supposed to get a soaker for the next few days, so we’ll be happy to see that.

“We are spraying some fields for bollworms. We don’t see widespread issues, but we definitely have early pockets. The moth flight is steady, and we haven’t seen it tick down yet.

“Most of the questions involve taking out plant bugs and stinkbugs without flaring those things that have been nagging us all season, such as spider mites and aphids. The primary question is: ‘Should I add an insecticide to the tank when I’m making a trip across the field?’ The answer is, ‘It depends.’

“Fortunately, stinkbugs have been light all season across crops, and folks are talking about how light they are in cotton. Growers in northeast North Carolina aren’t getting a break from plant bugs. It’s too early to call it a heavy year, but we sprayed more than usual in the central Coastal Plain. Outside of that area, we only see scattered plant bugs populations.

“We expect worm calls from soybean farmers to start next week, and more sprays are going out.”

 

Phillip Roberts, Extension Entomologist, Tifton, Georgia

“Scattered pop-up thunderstorms have been developing, and we desperately needed rain on our dryland cotton. Some fields received it, others haven’t yet. On dryland acres that haven’t gotten a rain, the cotton is suffering, and it’s been a while since a good, gentle rain fell across a wide area.

“Overall, four pests are on everybody’s mind – whiteflies, spider mites, bollworms and stinkbugs.

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“We are seeing high levels of adult whiteflies moving into localized areas. We continue to treat fields at threshold. Where we made timely treatments, everything is going okay.

“Whiteflies appear to be slowly spreading to counties adjacent to our historical range, and during the last week folks started picking up low levels in those areas. We absolutely must scout regularly. It’s important to know when they arrive and at what level.

“Delaying treatment until threshold is essential for economic management of whiteflies, but we can only make that call when we know how long they have been in the field. We must be on time, especially with insect growth regulators (IGRs). If you are making a late application, those IGRs are not the product of choice. You need to use a contact, systemic-type product.

“Spider mites are still an issue – more so than ever. Sometimes we can live with them, but in other cases they increase and we have to treat. More frequent and consistent rainfall will help, but it won’t necessarily solve the problem. There was a time when rain would take out mites, but now it’s more likely to just slow them down.

“I have talked to scouts who reported larvae in two-gene Bt cotton, but for the most part we are only running at 2% or so. With numbers still relatively low, we haven’t treated a lot of acres specifically for corn earworm. Whether we treat depends on the level, so right now we just need to watch for them.

“We also only want to treat stinkbugs if necessary. The goal is to keep our beneficials in the field.”

 

Eddie McGriff, Regional Extension Agronomist, Northeast Alabama

“Scattered rains have developed but nothing substantial or widespread yet, which is what we need. The crops are starting to noticeably suffer.

“Insect pressure is scattered. Mostly, aphids failed to develop in the high populations that we usually contend with in northeast Alabama, and that’s a blessing. We are seeing scattered spider mites, especially where farmers made multiple applications for plant bugs and/or thrips.

“We’re preparing to harvest corn and are scouting cotton and soybeans. We haven’t seen a lot of worm pressure yet in either crop. Bollworms usually start appearing the first week of August, and anyone with two-gene cotton needs to watch for escaped bollworms.

“Also, scout for stinkbugs in cotton and soybean. Right now, we’re phasing from plant bugs into stinkbugs.

“We are detecting potassium deficiency in some cotton fields, largely because we’re not taking up enough water so we’re not moving enough potassium to support the boll load we have. We also are seeing restricted root systems in some fields because of a shallow hardpan, and that reduces nutrient uptake.”

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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