Cotton – Southeast – Insects Ramping Up, Whiteflies Add Complications In Lower Region – AgFax

©Debra L Ferguson Stock Photography

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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

Whitefly populations continue increasing in the lower Southeast, and they are expanding their 2020 range in the process. People who endured whitefly infestations in 2017 well understand how costly and destructive this pest can be.

Excessively hot and dry conditions are working against the crop, plus pushing whitefly and spider mite populations higher.

Bollworms, stinkbugs and plant bugs are popping up in scattered fields, some heavier than others. Overall, though, stinkbug pressure seems lighter than normal across parts of the region.

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CROP REPORTS

Wes Briggs, Briggs Crop Services, Inc., Bainbridge, Georgia

“It’s hot – hot and excessively dry, and we need rain. A lot of the dryland cotton acres are aborting fruit. Rain right now would help fill out bolls, but we will lose some top crop regardless.

“Our irrigated cotton is carrying a lot of fruit and looks healthy. Cotton ranges from the first week of bloom to the first week of open boll, with some just going into bloom next week.

“We’re probably four weeks from defoliating our oldest cotton. Pivots are running non-stop, and growers are cutting them off long enough to change the oil and make repairs. We can keep up on our heavier, stiffer dirt. On our sandier land, we’re barely able to keep up using only pivots.

“Rain helps us in a couple of ways — delivering moisture and also lowering temperatures. This cotton needs a break from these high temperatures.

“We completed layby in most of this cotton, so we’ve essentially finished weed control. A few growers are pulling pigweed.

“In some fields, folks are battling four pests at the same time: stinkbugs, escaped bollworm, spider mites and silverleaf whiteflies. For the most part, we evaluate which two are pressuring the crop the most and which put the crop at the highest risk, then we treat for those.

“Silverleaf whiteflies (SLWF) are in southwest Georgia, southeast Alabama and the Florida Panhandle, with higher numbers on the Alabama-Florida line. We are treating, but we’re trying to be careful about what we’re using when we spray. We will likely end up spraying about 75% of our acres for SLWF – and that may be a conservative estimate.

“Last week we primarily saw SLWF adults. This week we’re finding adults and immatures. Next week will be a big week in my area. On our oldest cotton, we may get by with one whitefly spray, but our youngest cotton has a long way to go. If Mother Nature helps out with some rain, that will help us. Otherwise, the younger cotton definitely will need a follow-up SLWF application.

“Disease pressure, on the other hand, is low. We only sprayed two fields for target spot. Unless we start getting some rain, we don’t expect that pressure to increase. If it does rain, we’ll be on the front side of that.

“In peanuts, we will start checking maturity in our oldest peanuts in about two weeks. If it stays dry, some of these dryland peanuts may go to harvest on the early side, which isn’t good. We sprayed a majority of our peanuts for a combination of loopers, corn earworm and a few velvetbean caterpillars. We’ll also be going into another moth flight in cotton and peanuts soon.

“We have done an excellent job controlling white mold and leaf spot up to this point, but we still have a long way to go. We’re just in the first week of August, and August is a big month for us to set fruit in peanuts and cotton.

“Corn yields have been on the positive side. We are seeing 230 bu/acre to 280 bu/acre. We’ll see a new crop report next week and expect USDA to increase the number of acres and the average yield, which could drop the price.

“We will stop irrigating our oldest Group IV soybeans next week. Our youngest soybeans still have a ways to go.”

 

Ron Smith, Extension Entomologist, Auburn University

“We are still focused on stinkbugs, plant bugs, bollworms and spider mites and we have one new emerging insect: whiteflies.

“Stinkbugs will be our dominant pest for the rest of the year. In the majority of older cotton fields in southwest Alabama we also have a hatch-out of immature plant bugs. In that early-planted cotton, growers can gain the advantage if they spray for plant bugs because they probably have some stinkbugs. One treatment can clean up both of those.

“We are finding a low level of bollworms in our sentinel conventional plots. We also are seeing some bollworms in our two-gene cotton planted in commercial fields.

“If the weather stays hot and dry, we can expect higher levels of spider mites.

“The pest we will watch closely for the next couple of weeks is silverleaf whitefly (SLWF). An independent crop consultant found whiteflies in Alabama late last Friday. It’s going to be a race to maturity in our older planted cotton. The younger planted cotton is at high risk to SLWF in our historical areas.

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“We don’t want to do any automatic spraying and we need to avoid any treatments unless a significant problem arises during the next six weeks. That doesn’t mean letting stinkbugs go wide open, but we should spray only when necessary. We need all the beneficials we can hold in the field.

“In peanuts and soybeans, velvetbean caterpillars are showing up on a majority of the acres in Southwest Alabama. They started appearing last week, and pressure is getting heavy this week. We’re only finding a few soybean loopers.

“Scattered thunderstorms have been infrequent in the last week, so we are in dry situations over much of the crop.”

  

Bryce Sutherland, S&R Ag Consulting, Sylvester, Georgia

“We caught some much-needed rain last week, and it was critical for a big part of the dryland acres I have.

“We are treating about 30% of our acres for whiteflies and nearly all those acres needed two treatments. Although the pressure isn’t as heavy as 2017, we are focused on making timely applications. Timeliness is critical.

“We have a few hot spots with spider mites, but so far have treated only a handful of fields. We are keeping a close eye on them.

“We are collecting samples for cotton leafroll dwarf virus. We need to learn about the virus, and part of that is evaluating whether varieties respond differently.

“We are finding target spot in the lower canopy on irrigated land.

“In peanuts, we are starting to see white mold on 80- to 90-day peanuts and we have scattered incidents of leaf spots. Most of the fungicide programs are holding up well. We treated a few dryland fields for lesser cornstalk borer. We’re seeing other worm populations increase, but we haven’t had to treat yet.

“Signs of dryness are showing up in fields and tomato spotted wilt virus is increasing, with more of it in the skippy stands. However, the level of tomato spotted wilt virus isn’t worrisome so far.

“Corn is drying down to heavy black layer and it looks like we’ll have a good crop, with a nice percentage of ears filling out to the end.

“We are about a week from harvesting grain sorghum. We treated nearly every acre for sugarcane aphid and wiped them out early. We also treated some acres for sorghum midge. Yield potential is pretty good. Even the dryland acres caught rains at the right time.”

 

Sally Taylor, Virginia Tech Extension Entomologist, Tidewater REC

“It finally rained in eastern Virginia. That’s good because a lot of our acres needed it. Hopefully, the rain also wiped out spider mites.

“Our restraint in spraying fields early-season is paying off. We have large populations of natural insect enemies in many fields, which in part can be attributed to non-economic aphid populations. As a result, we had few plant bug or bollworm sprays. I’ve never seen a year with these few pest problems in cotton.

“Bollworm pressure is light. Some of our moth traps in the central and southeastern part of the state started going up over the weekend, but we haven’t seen a huge influx of worms in cotton. We are currently scouting for eggs. I haven’t seen any worms in fruit.

“Everybody should check terminals and leaves close to blooms. If 25% of the locations you look at in any given field have eggs, we recommend a preventive spray.

“High numbers of foliage-feeding caterpillars have shown up in several peanut fields. Keep in mind that peanut can tolerate 4 to 8 worms per row foot, and we have found worms at that level in peanut fields this year. But I would definitely scout before spraying. Many fields are 100% clean.

“Low numbers of small worms have been showing up in soybean. At this point, check beans weekly for worms and stink bugs if you haven’t been doing so already.”

 

Scott Graham, Extension Entomologist, Auburn University

“Spider mites are picking up in southeast Alabama. That area has been hot and dry for a couple of weeks, so we expected more spider mite activity.

“If we look long enough, we can find an escaped worm or a damaged square, but bollworm pressure isn’t bad.

“Plant bugs have increased a good deal in north Alabama, with significant numbers of small immature tarnished plant bugs in drop cloth samples. We were below threshold at Belle Mina the last 2 weeks but hit three times threshold this week.

“Redbanded stinkbugs (RBSB) are in soybeans in the Black Belt region in west Alabama, but that’s the only area where we have received reports of RBSB. We have sprayed 12,000 to 13,000 acres, or about 5% of the crop in that region, and the treatments are working.

“We are just starting to pick up loopers in soybeans, including a few we found on the station in Prattville. At Prattville, we also found Beauveria bassiana, the fungus that control kudzu bugs. Surprisingly, we are still seeing kudzu bugs in the Black Belt region west of the station, but most are not at treatable levels.

“Stinkbugs are sporadic but seem to be picking up. In a trial in Prattville that was checked 14 days after spray the pressure was picking up in untreated plots and in treatments with a shorter residual.”

  

Jeremy Greene, Clemson University Entomologist, Blackville, South Carolina

“We didn’t get any rain here in Blackville from the hurricane (Isaias), and we are just 80 miles from the Atlantic Ocean. If a storm misses us on the east side, we get nothing or next to nothing, and we have seen this many times before.

“We’re finding more bollworm injury in cotton. We scouted some trials today, and most of the two-gene cotton looks good, but in some we found boll injury at threshold. In one field, we found damage to 6% of the bolls, 3% of the squares and 2% of the blooms.

“Stinkbugs are in the system. As long as we follow the dynamic boll-injury threshold for treatment, we should be fine. The question is whether we should protect some fields with additional sprays going forward.

“With this dry weather, at what point do we pull back on inputs? If a field gets rain, picks up and sets a renewed bloom and fruit load that offers good yield potential, then protect those bolls. In lower South Carolina – generally referred to as ‘below the lakes’ – we can harvest bolls that are set by early September. Above the lakes, bolls have to be set sooner to reliably reach harvest.

“Spider mites will probably be an issue in areas that miss scattered showers, making them another stressor for plants in dryland fields.

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“In soybeans, the situation hasn’t changed. We are finding a bunch of caterpillar species. It’s important to be able to tell green cloverworm from soybean looper because loopers are more expensive to treat. When they’re small, they both crawl with a looping action. The way to differentiate is to look closely with magnification at the abdominal prolegs. A caterpillar with two pairs of abdominal prolegs is a soybean looper and three pairs is a green cloverworm.”

 

Phillip Roberts, Extension Entomologist, Tifton, Georgia

“Whitefly numbers continue to increase and are spreading farther outside our historical areas. It’s important to know they’re present. Where populations are low, we need to try to preserve beneficial insects.

“It’s a race to the finish. April-planted cotton and early May-planted cotton may make it to the finish line before we have a whitefly problem. But we must closely scout cotton planted in mid-May and June. The pressure is so much higher on cotton that’s smaller, generally those later-planted fields. Whiteflies are really attracted to young cotton.

“Be on time with treatments. Never get behind with whitefly. We learned a lot the hard way in 2017. If we can be on time, we can avoid learning those lessons again.

“On the fringe areas where we’re seeing a few whitefly and maintaining beneficial insects, we can watch closely and delay treatment. If we can delay a whitefly application for two weeks, that’s one less insecticide application. Anything we can do to delay treatment is money saved.

“Although we certainly don’t want to be late, we also don’t want to be too early. Scout at least once a week. If a field is near threshold, come back in three or four days. Whitefly populations can change dramatically and quickly. We don’t want to play around with this guy.

“These hot, dry conditions are not good for whitefly management. Even in our core area, we have a fair amount of acres that were already treated twice and we’re starting our third spray on some of that. But the cotton is looking good.

“For the last three to four weeks we’ve seen a caterpillar here or there in two-gene Bt cotton. Those fields were in close proximity to field corn. We need to scout. Once you detect an issue, get in there quickly. We have a handful of fields at threshold, with a few higher than a 20% infestation. In the same fields, the three-gene Bt cotton looked perfect.

“We’ve been fortunate for many years in Georgia that we haven’t had high corn earworm pressure, and this may be an isolated event. But, it’s a warning to folks that it can happen. We need to be prepared.

“Stinkbug pressure is below average, and that’s a good thing. Trust your scouting. We have more confidence in our thresholds for stinkbug than we do in any other insect in cotton. Especially with the whitefly situation, don’t spray if you don’t need to. Let’s preserve these beneficial insects.”

 

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

“Following Hurricane Isaias, we have some tobacco that’s twisted and some corn that’s twisted and laid over. In places, farmers really needed the rain, so the jury is still out on whether the rain did more good than the wind did damage.

“Regardless of the hurricane, our crops are suffering. We have some bright spots, but mostly it’s not a good year for anything – including crops.

“A few cotton fields have been sprayed for bollworms. Growers primarily are going after stinkbugs and plant bugs. Pressure is spotty. Bollworms are variable, too. Some pheromone traps are ticking up while others are ticking down. Fields with moths may be next to a field with no moths.

“Consultants are so valuable because they identify which fields have insects at levels that require treatment.”

  

Larry Walker, Walker Cotton Technical Services, Flintville, Tennessee

“Cotton is right at peak bloom, so we have several weeks left. We had showers over the weekend (8/1-2), and ample amounts of rain fell in July. We hope to be finished or only have one more Pix application left to make, but we are working with some pretty tall cotton from all the rain in July. 

“In July, alone, we got over 5 inches. We are already over our annual average of 52 inches, and I think we have been over the monthly average every month since December 2019. One projection says that August will have average to above-average rainfall, as well. We do need the rest of the rain in August to finish out the crop. It hasn’t wilted a single day, and we are not looking to start that now.

“The cotton has to have a pretty shallow root system from all those many days it sat in saturated soil. It’s grown a lot on top in the past month, so surely the cotton put down some more roots.

“Insects have been light. We sprayed over half the crop for thrips, and we’ve sprayed for plant bugs. We’re feeling good about moving into August with the crop we have. A couple more insect sprays should round out the season if everything goes like it has been.

“Some of our MG III beans planted on high red soil look really good. Those beans are two-thirds grown in the pods and are relatively insect-free. 

“Double-cropped beans behind wheat already have threecornered alfalfa hoppers, green cloverworms and loopers. They were finally planted around July 1 and are a couple of feet tall. The double-crop beans still need rain, weed control and insecticides. 

“We are starting to see spotty efficiency rates with Engenia killing pigweed. We made an application and took out a lot of pigweed, but some was left. Going forward, we’ll have to expand our herbicide rotations to take care of those issues.

“Corn is past the dent stage, but the latest-planted is really going to need rain in August.”

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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