Cotton – Southeast – Whitefly Treatments Just Ahead? – AgFax

Whitefly adults and eggs. Photo: James Castner, University of Florida

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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

Whiteflies top the scouting priority list in the lower Southeast. Populations may be building, and scattered treatments might be needed before the end of July. See comments by Phillip Roberts.

Bollworm pressure remains spotty. Scout fields intensely but keep a light hand on the insecticide trigger. Give your Bt traits the opportunity to prove their worth, Extension personnel advise.

More optimism, perhaps. Rainfall across the region improved the general outlook for this crop.

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CROP REPORTS

Ron Smith, Auburn Extension Entomologist:

“Cotton planted before May 5 is in the fourth or fifth week of bloom, and some of those fields still have not been sprayed for stink bugs or plant bugs. If you have any of that cotton and haven’t treated for stink bugs or plant bugs, consider cleaning up the bugs now. When the other cotton moves into the third week of bloom, we need to clean it up, too. Stay on top of plant bugs and also make sure we don’t let the stink bugs get out of hand.

“A light flight of corn earworms started a few days ago. The numbers aren’t high, nothing unusual, but we picked them up last week and saw more this week. Recent rains suppressed spider mites, so they’re not an issue right now.

“A consultant reported brown marmorated stink bugs in cotton near Orrville, Alabama. That’s the first report of brown marmorated in that area. They tend to feed more intensely on the borders and will feed on all boll sizes, which makes them different. We can control them with just about any stink bug insecticide.

“In soybeans, the significant point with redbanded stink bugs (RBSB) is that scouting for them isn’t easy. The time of day makes a big difference when surveying for RBSB. Early and maybe late are the best periods to check for them with a sweep net. In mid-day, it’s impossible to pick them up with the net. But in the early morning when soybeans are still wet, the insect isn’t as likely to fly away when you do sweep.

“In peanuts, my son (consultant Shane Smith) found velvetbean caterpillars and we are coming across an occasional soybean looper or green cloverworm, but nothing at threshold levels.”

Jack Royal, Royal’s Agricultural Consulting Co., Inc., Leary, Georgia:

“We expect a corn earworm light around this time or a littler earlier, but it hasn’t materialized yet. We’re finding a few worms, but none of those large escaped worms so far. We’re checking blooms, bloom tags and eggs and are staying on top of it because this corn earworm situation could change at any point.

“Stink bugs are still moderate to heavy.

“No disease yet. We are still irrigating. Although most places caught a rain, very few locations received adequate amounts.

“Just about all of our cotton is in bloom – some into the fifth week, in fact – but nothing has shown up that we couldn’t handle. Staying on a good schedule is the biggest deal.

“In peanuts, conditions are right for white mold, but my growers stay on schedule with fungicides. We have sprayed less than 5% of our peanut fields for corn earworm.”

Jeremy Greene, Clemson University Entomologist, Blackville, South Carolina:

“Right now, we are managing stink bugs and trying to determine how heavy bollworms might be in this year’s cotton crop. They’re always out there and testing the fences, so to speak, trying to figure out how to break through.

“We used to be able to apply a pyrethroid to control stink bugs and catch any escaped worms, but control is slipping a bit with pyrethroids on bollworm. Pay attention, scout for worms and watch thresholds.

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“We surveyed a small sample of fields for plant bugs this season, but they reached threshold in only a small percentage of those fields.

“In soybean, a few soybean loopers are showing up early. We’re coming across velvetbean caterpillars and green cloverworms. We have a combined defoliation threshold for all of those foliage feeders. Prior to mid-bloom we can stand 30% defoliation, but after mid-bloom – when we have pods on the plant – the threshold drops to 15% defoliation.

“When you see that level of defoliation, go in with a drop cloth before deciding on a treatment plan. Determine what is feeding on leaves. If it’s soybean looper, you’ll need to go with a selective insecticide. If it’s anything else, we can apply a pyrethroid.”

Brad Smith, Nutrien Ag Solutions, Selma, Alabama:

“Overall the crops look good, and some corn probably will make it to black layer this week.

“In cotton, we’re treating stink bugs. Aphids are no longer here, either due to treatments or the fungus. We’re treating weed where they haven’t already been addressed. Plant growth regulators are going out. We expect cooler temperatures later this week.

“We recently found areolate mildew in cotton in Elmore County, and that’s the only issue of immediate concern. Hopefully, it won’t spread, but we’re keeping an eye out.

“Fall armyworms are showing up in pastures and in grain sorghum, which we always expect in late July.

“In soybeans, we’re seeing foliage feeders and stink bugs. We’re cleaning up stink bugs and making fungicide sprays in the MG IVs and most of the MG Vs.”

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

“The insect side is the only good news for our cotton crop right now – it is quieter than usual. It started out as a real buggy year. The stink bugs were earlier and more numerous than usual in corn and cotton, but that’s quieted down.

“In soybeans, stink bugs are getting in the fields at R3 to R4, and I encourage growers to be protective at that stage. We don’t usually see them until R5.”

“In cotton, we’re paying close attention to bollworm. For 3-gene cotton, I encourage growers to stick to the threshold and save their money. We haven’t seen a yield benefit to spraying Bollgard III, Widestrike 3 or TwinLink Plus.

“Bollworm are around but not as many per acre as you might expect.

“We also don’t need to control bollworm to manage for resistance. That idea seems to be floating around this season. A widely accepted Southeast study used the gossypol marker to determine the percentage of moths that come out of cotton. That percentage is really, really low – less than 1% between mid-June and September, with a late-season increase to 19% in September. For me, that was a surprising finding, but that’s the state of knowledge on it right now.

“In 2-gene cotton, we have sprayed for bollworm eggs. A lot of growers are moving to 3-gene cotton because companies are using 3-gene traits in all of their new varieties. Growers who are planting a 2-gene variety that’s yielding well can include the cost of a worm spray in their program.

“We do expect worm pressure to increase after this dry spell ends. The species can survive through what’s known as facultative diapause. That means it’s hot and dry, and the larvae will wait in the soil for better conditions. That’s why we often see a population increase once the weather breaks after an extended stretch of hot, dry weather.

“In late-planted corn, watch for fall armyworms. A fair amount of fall armyworm is around and they can put a hurting on ear-stage corn. I’m not so worried about whorl-stage, but we need to protect our ear-stage corn. For soybean fields, it’s too early to tell, but the species that puts a hurting on corn can infest soybean, as well.”

Bryce Sutherland, Extension Agent, Worth County, Georgia:

“We are managing cotton at a lot of different stages, but the crop is progressing well overall. A blanketing rain last weekend helped. On the older cotton, we’re moving into the critical blooming period.

“We’re scouting closely, following stink bug recommendations and treating threshold populations. In 2-gene cotton, we’re finding corn earworm escapes but nothing at threshold yet.

“Low levels of silverleaf whitefly are showing up in cotton. Nothing has reached treatment level, but we’re monitoring closely. Growers need to evaluate populations and make treatment decisions carefully.

“With watermelons finished up in the county, let’s quickly destroy those fields. We understand the value and purpose of pinhookers, but watermelon fields provide a whitefly haven, and we must break that lifecycle.

“In peanuts, caterpillars are picking up, but we haven’t found any fields at threshold – yet. Conditions are really good for white mold, and we’re seeing that.”

Sally Taylor, Virginia Tech Extension Entomologist, Tidewater:

“Insects are quiet in cotton with the exception of a few problem lygus fields. Moth trap catches have started to climb this week and we are finding eggs in cotton. Scout closely and follow our trait-based threshold recommendations.

“For 2-gene cotton – Bollgard II, Widestrike and TwinLink – I recommend spraying Prevathon or Besiege when you find 25 eggs per 100 terminals or leaves. This strategy is only recommended with these two insecticides. I do not anticipate needing to spray 3-gene cotton for worms. That includes Widestrike 3, Bollgard III, and TwinLink Plus. Spray that cotton only if you find live worms.

“This week we are starting the annual bloom survey for lygus in cotton. Information from that will be provided on Friday, July 26, on the Virginia ag pest advisory website.”

De Broughton, Florida Regional Specialized Agent, Live Oak:

“In peanuts, disease is emerging – low occurrence of early leaf spot and instances of white mold. Also, we are seeing significant amounts of Aspergillus niger – much higher than usual. Plant stress at planting probably gave aspergillus the opportunity, and some of those rot problems have surfaced and continue to grow.

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“Problems with root-knot nematode are showing up in multiple counties. Once a field has them, you must create a management strategy. We also are finding some lesser cornstalk borers. When it starts to rain, they usually head for the hills, but that hasn’t been the case this year. We’ve had to spray for them more than normal.”

Phillip Roberts, Extension Entomologist, Tifton, Georgia:

“Silverleaf whiteflies are building in places. As a whole, numbers are still low and we’re hoping this rainfall will help. But in all likelihood, we’re going to hit our threshold in hotspots in the next 7 to 10 days.

“When they reach threshold, treat immediately. In the meantime, do everything to avoid the need to treat whiteflies. Controlling this pest – this expensive pest – requires a cooperative effort among all growers. Whether you’re a vegetable grower or a cotton grower, we all need to do our part to keep these numbers low.

“If you have a vegetable field, destroy that field after harvest so whitefly don’t use it to build their populations. If you’re a cotton grower, defoliate fields in a timely manner so whiteflies don’t continue to build before they shift into fall and winter vegetables.

“In Georgia, we produce crops year-round that are whitefly hosts. What we do in cotton will impact vegetables. What we do in vegetables will dictate how whitefly affect cotton.

“Our greatest chance for managing this pest is doing all those little things. Cotton growers can preserve beneficial insects, consider leaf hairiness when choosing cotton varieties, and defoliate in a timely manner. Also, pay attention to whitefly when making stink bug treatment decisions. When whiteflies are present, avoid stink bug insecticides that flare whiteflies.

“For additional information about controlling whitefly, study our guide: Cross-Commodity Management of Silverleaf Whitefly in Georgia.”

Johnny Parker, Agronomist, Commonwealth Gin, Windsor, Virginia:

“A nice rain this week set up our cotton for a top crop. For all but the late crop, we probably can expect a long boll-set period. That, along with good yield prospects, creates a longer period when protection is needed.

“The first 3 weeks of bloom usually sets enough bolls to make average yields if we keep them protected. A bloom-timed insect spray now protects this core part of the crop. Intensive scouting can sometimes allow you to delay this spray, but scouting is more likely to confirm that you need to treat. In years like with a late July soaker, we expect to set bolls from the fourth and fifth week of bloom, with prospects for above-average yields.

“Although we’re in the middle of making the first bloom spray, bolls from these later blooms also need protection, so we can already predict the need for another trip.

“For late cotton or big cotton with a good bit of growth over the blooms, be aggressive with plant growth regulator (PGR) now. If your cotton is already 7 to 8 NAWB then you do not need to add any more growth, and I recommend an aggressive PGR approach following rain.

“Alternatively, cotton with blooms up high – 5 NAWB) – will stop blooming before the last effective bloom date and can benefit from more growth now. Larger growing, indeterminant varieties that are short now will go back to growing later and get big in late August and September.

“When the growth gets up to about 40 or 45 inches in July, cotton isn’t likely to start a later growth spurt because it is putting energy into August bolls. We can add PGR on that second bloom spray in August if you leave it out now.”

ALSO OF NOTE
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If the US crop gets larger, that’s not altogether a bad thing (it’s a good thing from a farm level production standpoint)—but it would place more emphasis on strong demand and strong exports.
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U.S. cotton exports to China have fallen, along with domestic prices, while stocks climb.
cotton-plant-bug-20120731_DFerguson_064-150x150%5B1%5D.jpg
In most seasons, we would be entering the home stretch for cotton insect control by early August. While this may be true for fields planted on time in 2019, it is not the case for a lot of late planted, late emerging, late maturing fields this season.
cotton-harvest-john-deere-Nick-McMichen-Alabama-IMG_0113-150x150%5B1%5D.jpg
The field day will feature presentations and research findings from UGA College of Agricultural and Environmental Sciences researchers with an emphasis on cotton, corn, peanuts and soybeans.
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Live from New York…the panel will discuss today’s cotton market including, crop conditions, domestic demand, exports and farm policy.
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.
©2019 AgFax Media LLC


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