Cotton – Southeast – Plant Bugs Influencing Treatment Decisions As July Starts – AgFax

i
Pam Caraway, Contributing Editor

Owen Taylor, Editor

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

OVERVIEW

Tarnished plant bugs are the main focus this week across a significant portion of the region. Although plant bugs are widespread, few fields have hit threshold. Extension personnel continue to emphasize the value of scouting to determine whether to treat and which materials to apply. Spider mites and whiteflies are around and could flare quite easily if harder insecticides take out beneficials. That’s aside from the fact that those friendly insects help against worms.

The aphid fungus has developed in places. Hopefully, it will soon arrive on a wider basis, but the fungus also can be a fickle friend. As one contact this week noted, the fungus tends to turn up later if the cotton crop also is running late.

No reports this week of cotton leafroll dwarf virus.

In peanuts, lesser corn stalk borers are reaching treatable levels in some areas. Caterpillars also are building in places.

i

CROP REPORTS

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

“Our cotton ranges from about the fifth leaf to the second week of bloom, which presents management challenges with the crop being so spread out. The good news is we’re getting a good rain right now (6/30), and we needed it.

“Tarnished plant bugs are the main issue. Although infestations are hit or miss, we’ve probably sprayed 25% to 30% of our cotton acres for plant bugs, which is higher than usual for Georgia.

“We found the aphid fungus over the weekend. We’re on the front end of the fungus helping us control aphids, but our aphid numbers are nowhere near where they were last year. Typically, we don’t spray for aphids in Georgia unless they’re on really young cotton. What we applied for tarnished plant bugs on those 30% of the acres also controls aphids.

“We are on the front end of a corn earworm flight into cotton. Spider mite are showing up at low levels in older cotton. We’re sidedressing nitrogen and plant growth regulators are going out, too. For the most part, weeds are under control.

“Further complicating our existing stand issues in peanut, more tomato spotted wilt virus has developed, plus we have heavy pressure from aspergillus crown rot. The stands are getting worse and worse. Where you were at 3.5 to 4 plants per foot, certain fields are now at 3 plants per foot or less after aspergillus and spotted wilt further thinned the stands.

“Pressure from lesser cornstalk borers is increasing. This rain will help pack the soil, which should help because lessers need sand or loose dirt to make their web tunnels. Without that loose dirt to build a place to live, birds and beneficials will pick them off.

“We don’t see any white mold – yet. We are carefully scouting for it because conditions are right and underground white mold will bite you worse than anything. Growers are busy putting out fungicides. Some acres are receiving the first treatment, others are on their second. Gypsum applications are complete now on a most of our peanuts.

“We went through a bit of a dry spell in June but are receiving rain now. That’s good. We’d rather be dry in June and have rain in July and August. I hope our moisture holds up.”

 

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

“We are spraying stinkbugs in corn. Although counts are light to moderate overall, some fields are under heavier pressure.

“Insect activity is picking up in cotton. On the northeast Virginia border, we think we have Asiatic garden beetles in a few fields over a wide geographic area. It’s an invasive insect, and this is the first time I’ve seen this beetle in cotton. Growers effectively treated them.

“Cotton is so far behind. We are starting to spray tarnished plant bugs now, primarily in the areas where we expect to see heavy populations. We need to remember that broad-spectrum treatments can flare spider mites. We recommend rotating the recommend soft-chemistry products to preserve beneficial populations. This is just the beginning of a season-long battle with tarnished plant bugs. They’re not widespread, but we definitely need to scout.

“We typically spray our soybeans for corn earworm (CEW) in July and August. CEW cycles through corn, which is pollinating now, so CEW will be right on time in soybeans. We are also spraying soybean for kudzu bugs, which are starting to produce immatures. They really like early beans, so that’s where folks should focus their scouting.

“The bright spot is that stinkbugs were lighter in corn, so we hope to see less pressure this year in cotton and soybeans.”

 

Eddie McGriff, Regional Extension Agronomist, Northeast Alabama

“Widespread rain to the tune of about 2 inches fell early this week, which was great for all of our crops. That’s especially true for corn because the majority of the crop is coming into silk, tasseling and pollination. Our corn crop is later than normal, so the cooler temperatures that the rain brought are welcomed and will help with pollination.

i

“Insect and disease pressure is fairly low in all of our crops. We are concerned about plant bugs in cotton, so keep an eye on square retention and plant bug numbers.

“Peanuts are starting to peg. We are seeing a little spotted wilt, but nothing to be concerned about. Because we are fairly new to peanut production in this part of Alabama, we tend to have lower disease pressure on this fresh ground.”

 

John Burleson, Consultant, Swan Quarter, North Carolina

“Water stress is a problem in our cotton and corn, although not so much in our soybeans. Soybeans and cotton put on a lot of growth in the last 10 days – more in the last 10 days than in the last two months. Our cotton is probably running a month behind normal, and that’s a conservative estimate.

“Soybeans are all over the board, but that is normal because we usually have a mix of planting dates. Corn ranges from V8 to silking. Some growers are putting out fungicide on corn, and stinkbug pressure in corn is low.”

 

Brandon Dillard, Seed Certification Associate, Alabama Crop Improvement

“As late as it is, some people are still spotting replants into skippy peanut stands.

“We are seeing a few worms in peanuts, but I haven’t heard of any sprays going out yet.

“Aphid problems in cotton are limited, which may be due to these regular rains. We are seeing a lot of stinkbugs and plant bugs in cotton. Most growers are adding a treatment for them when they go across the field with weed control or when applying a plant growth regulator.”

 

Sally Taylor, Virginia Tech Extension Entomologist, Tidewater REC

“High plant bug numbers are turning up in less than 5% of our cotton. If you’re not scouting and wonder whether to apply an insecticide, my money is on ‘no’. The sure bet when making a treatment decision is to scout.

“Some peanut fields started showing leafhopper injury in the past two weeks. That includes yellowing and subsequent browning of leaf margins starting at the tip. Remember that this is non-economic impact until 20% to 25% of foliage is affected. Also, check to see if insects are actually present before applying insecticide.”

 

Ron Smith, Extension Entomologist, Auburn University

“More cotton fields are reaching the bloom stage each day. Tarnished plant bug is the main insect we’re concerned about. Many fields are at sub-threshold levels with adults. A lot of these fields are getting treatment because the grower is going over the field with a plant growth regulator and boron anyway.

“The wet weather has extended the migration because wild hosts have remained viable and attractive longer than usual. So, we could be contending with drawn out pressure from plant bugs.

“Immature tarnished plant bugs are showing up in April-planted cotton. We can use the 80% square retention level to decide whether to treat, but also factor in the physiological shed that we occurs after a number of days of cloudy, rainy weather. For several days following a wet and cloudy period, square loss may not all be due to plant bugs.

“The bright side of wet, cloudy weather is that spider mites aren’t likely to spread. However, they don’t go away. Spider mites likely will be a major concern if we get into a hot, dry period later this season.

“Aphids are building, and that’s another factor in deciding which chemical to use for plant bugs. We are only seeing them on the occasional plant, so our aphids are late. That means we may be dealing with aphids for several weeks. When they’re just on the occasional plant, I’ve never seen them die off from the fungus. The populations have to build for that to happen. My experience is that when the aphids show up late, the fungus shows up late, as well.

“Growers and consultants are wise to consider the impact on spider mites and aphids when making treatment decisions for tarnished plant bugs.”

 

Phillip Roberts, Extension Entomologist, Tifton, Georgia

“Aphid numbers are still building, but we are finding isolated hits of fungus. We haven’t seen a lot of fields crashing, but hopefully it’s coming soon. To gauge whether the fungus has developed, look for those gray, fuzzy aphid cadavers in the fields. Hopefully, those will start showing up this week, especially in the hardest-hit areas in the southwest corner of the state. We typically see the fungus start in that corner and then move north and east.

“Be vigilant about scouting for plant bugs. Populations seem to have moderated, but we still have fields that need treatment. If you have a problem, address it. If not, let our beneficial populations continue to multiply.

i

“As cotton fields start building bolls, look for internal boll damage from stinkbugs and treat accordingly.

“More people are reporting spider mites. To date, only a few fields have been treated, but plenty of folks tell us that spider mites are present. If we apply the wrong product when spider mites are present, we can blow them up.

“Whiteflies are increasing in the areas where we historically see treatable levels. Compared to the last two years, these numbers are elevated. Scout carefully because it’s important to know whether whiteflies are present so you can make appropriate treatment decisions.

“Rain is in the forecast over the next few days, and we hope that’s how it works out, but the crop is still progressing nicely.”

   

Jeremy Greene, Clemson University Entomologist, Blackville, South Carolina

“Aphids are still hanging around. We need to watch them, look for signs of the fungus taking them out, and check for signs that the aphids might be transmitting the cotton leafroll dwarf virus.

“Generally, though, we don’t need to treat for aphids. We continue to learn more about the virus and vector combination, but we are not recommending insecticide use for cotton aphid unless the situation is clearly an issue, and the stress needs to be alleviated. That is rarely the case, though. 

“We have a lot of data indicating that aphid sprays almost never pay for themselves, but we will keep researching the topic in the context of this ‘new’ viral disease.

“In a survey of eight grower fields – both dryland and irrigated – none of those locations exceeded the threshold for tarnished plant bug on pre-bloom cotton. The fields were in Calhoun, Orangeburg and Barnwell Counties,

“The average across all the fields was about a half-threshold. A couple of fields were nearly at threshold and square retention was 89% to 97%. We will survey those fields post-bloom and will likely add more fields to the sample.

“For now, tarnished plant bugs could be a problem in an estimated 10% of our fields. Although we certainly will have a few fields that are over economic threshold, this is good news. With 50-cent cotton, growers don’t want to have to put money into managing insects that we don’t typically battle.

“Most of the fields sampled carried healthy populations of beneficials – big-eyed bugs, lady beetles and such. We need to protect those beneficial populations until cotton is into bloom and when corn earworm/bollworm arrive.

“We collected more than 400 corn earworms from a non-Bt corn plot Tuesday and Wednesday (6/30 and 7/1). They will soon be going to ground, turning into moths and flying out to find blooming cotton and soybean. In pheromone traps, tobacco budworm numbers were recently higher than corn earworm, a situation that likely can be attributed to peanut acres in the area.” 

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.
©2020 AgFax Media LLC



The Latest


Send press releases to Ernst@Agfax.com.

View All Events


Send press releases to Ernst@Agfax.com.

View All Events