Preparing For Early Season Pests

VIRGINIA | Hunter Frame

In Virginia’s climate, early season growing conditions can be highly variable during the month of May. Thrips are the No. 1 pest in Virginia, and there seems to be concerns of insecticide resistance to commonly used chemical control products. Technology traits within certain cottonseed brands provide good control of thrips injury; however, for resistance management, this cotton needs to be scouted as well.

The standard program for thrips management in Virginia has been a foliar acephate spray at the first true leaf growth stage or in-furrow insecticide applications at planting. Seed treatments offer some control, but the foliar or in-furrow insecticide applications are often better performing. We cannot control the weather, but for optimal early season growth, cotton needs to be planted when soil temperatures are greater than 65 degrees Fahrenheit and days are on a warming trend after planting. This will ensure that cotton seedlings are rapidly growing and will be less at risk from severe thrips injury.

In 2023, May was one of the coolest on record and in some cases, cotton was sprayed twice with acephate to alleviate thrips injury. This was due to cotton not rapidly growing, causing thrips injury to be more severe than in years where cotton was developing new growth rapidly and able to withstand thrips feeding. Thrips injury will delay cotton maturity, though predicting yield losses is difficult. The best management is actively scouting and using chemical control products that your Extension entomologist recommends. whframe@vt.edu

NORTH CAROLINA | Guy Collins

May is when widespread planting is underway in North Carolina. As I write this March 28, there’s no way to foresee what planting weather will be like in May. Frequently monitoring conditions on your farm using the Cotton Planting Conditions Calculator (https://products.climate.ncsu.edu/ag/cotton-planting/) can help you navigate through the planting season. Ideally, we’d have 50 DD-60’s accumulated in the first five days of planting, but the calculator can help growers to know when to avoid planting and when to resume. Adjusting seeding rates according to planting conditions and seed quality remains to be important in ensuring adequate stands.

Beyond stand establishment, early season weeds and insect pests are likely the next in line in terms of where our attention will be given, and I’m sure that last year’s issues with thrips will not soon be forgotten. During the spring of 2023, we had a perfect storm for thrips in that we had enormous thrips pressure, prolonged slow early season growth that magnified the problem, and in many cases, acephate resistance. Heat unit accumulation during that time was sufficient for achieving good stands, with little replanting, but was lacking in terms of heat needed for rapid seedling growth. This lasted well into June, which is unusual for us.

The acephate resistance was new to us, and was spotty, therefore acephate was sprayed in a few cases without a quick follow-up evaluation of efficacy. This allowed thrips to feed noticeably longer before they were properly addressed using products like Radiant+surfactant. This delay in effective treatment further magnified the problem. With regard to thrips, years like 2023 are rare. With that said, several growers are likely tempted to plant some ThryvOn cotton, which clearly has an advantage when it comes to thrips. As of now, we don’t know what the 2024 planting season will hold for thrips, but using the NCSU Thrips Infestation Predictor (https://products.climate.ncsu.edu/ag/cottontip/) can certainly help growers understand when to plant to minimize thrips problems,  when during the planting window they will get the most benefit from ThryvOn or which fields may need more attention/management for thrips. guy_collins@ncsu.edu

TENNESSEE | Tyson Raper

As you read this at the beginning of May, we are hopefully on the cusp of planting a large percentage of our acres. As you are looking at the forecast to determine when to plant, I would encourage you to think about the conditions in which you have seen your stands fail.

Over the past several years, I have had an opportunity to plant in a range of adverse conditions, both from a temperature and rainfall standpoint. While I would prefer to plant into soil that is 65 degrees Fahrenheit or warmer at an inch depth at 9 a.m., I have frequently been able to achieve excellent stands when planting into soil temperatures much, much cooler than I would prefer.

From my experience, the “nail in the coffin,” which creates most environmentally driven replant situations, is an excessive rainfall event immediately following planting. I bring this up because occasionally we are given a slightly cool but dry window at the end of April or in the first few days of May. I am becoming more comfortable planting in those cool, dry windows based on these observations. traper@utk.edu

MISSOURI | Bradley Wilson

We are still a few weeks shy of planting in Missouri at the time of these comments. However, several early season pests can impact cotton growth following planting. Starting weed free can reduce early season insect pests but also benefits cotton growth due to reduced competition.

Thrips are a major insect pest early season in cotton through the four-leaf growth stage. Management options of thrips include an in-furrow insecticide or foliar insecticide application at the one- to two-leaf growth stage. Multiple applications may be needed if cool or slow-growing conditions are observed following emergence. New ThryvOn varieties on the market appear to be useful in early season management of thrips as minimal damage has been observed in Southeast Missouri. Severe storms and wind causing sandblasting to cotton following emergence can produce symptoms similar to thrips damage. It is important to confirm thrips are present and above threshold prior to making a foliar insecticide application.

Several soil-borne diseases can impact cotton emergence during our planting window. Planting into favorable soil conditions with a five-day warm outlook can reduce seedling disease incidence. When planting on poorly drained soils or in unfavorable conditions, in-furrow fungicide applications can provide greater protection against organisms that cause seedling disease.

Nematodes are a yearlong pest, but control options are limited to at-planting management options. Typically, root-knot nematodes are the dominant species in Missouri fields. Management options include cotton nematicide seed treatments, in-furrow nematicides and resistant varieties. Cotton seed treatments do not provide lasting control in fields with heavy infestations, and in-furrow nematicide applications will provide greater control. Resistant varieties have been observed to be the best option when planting into fields with high root-knot nematode populations. brwilson@missouri.edu

TEXAS | Ben McKnight

At the time of this writing the first week of April, planting of the 2024 cotton crop has mostly concluded in the Lower Rio Grande Valley and the Coastal Bend regions. Growers in the Upper Gulf Coast have been planting as weather conditions have allowed, and approximately 40% to 50% of the cotton crop has been planted in this region. Soil moisture conditions are in good shape throughout much of the state along the Gulf Coast, and currently no drought conditions exist from the Lower Rio Grande Valley all the way to the Louisiana-Texas state line. By the time you read this in early May, planting will be well underway in many of the other cotton production regions across the state.

In the late 1960s, Gail Buchanan and Earl Burns conducted trials in Alabama evaluating the impact of weed competition in cotton. Results from their work highlight the importance of keeping a cotton crop weed free for the first eight weeks following emergence to reduce yield losses resulting from early season weed competition. Over 50 years later, early season weed control is as important as ever, especially with the presence of herbicide-resistant weeds in many of our cropping systems across the state.

As a weed scientist by training, I am a big advocate for an aggressive weed management approach on the front end of the season. Residual herbicides can provide a foundation for effective weed control throughout the critical weed-free period early in the growing season, thereby reducing potential yield loss from early season weed competition. Additionally, residual products can greatly enhance our herbicide-resistance management efforts by reducing the pressure we put on postemergence herbicides applied later in the season on actively growing weeds. Overlaying residual products with postemergence applications can further extend weed control efforts longer into the growing season.

For many of our residual herbicide products, rainfall or irrigation is necessary for the product to be actively taken up by susceptible weed species. To maximize weed control activity and return value to our overall weed management programs, I encourage applicators to thoroughly familiarize themselves with each herbicide product label prior to making an application. A great resource covering all topics related to weed management for Texas cotton production can be found at the following: http://cotton.tamu.edu/Weed%20Management/2017%20Cotton%20Weed%20Control%203-15-2017.pdf. bmcknight@tamu.edu

TEXAS | Ken Legé

Our warm spring temperatures have growers anxious to get the season started. Similarly, weeds are also enjoying the warm spring temperatures, so growers have responded with yellow herbicide applications, as well as some burndown applications on the better-than-average cover crop in the region. Cover crops not only help reduce windblown sand damage for early seedlings, but under the right circumstances can preserve soil moisture. In West Texas, it is always a balancing act of allowing the cover to grow to adequate size, but then kill it in enough time to regain surface soil moisture for our cotton crop.

Recent data from Drs. Joseph Burke and Katie Lewis at Texas A&M AgriLife Research in Lubbock have shown that the amount of cover needed is not as much as many growers think. Their recommendation is to burn the cover down earlier rather than closer to planting since it doesn’t take much biomass to reduce wind erosion and windblown sand damage. It also gives you more time to rebuild soil moisture in the seed zone. See details of Drs. Burke’s and Lewis’ work at: https://www.txsoillab.com/.

Once we reach planting season, growers should focus on the following: 1) planting into a clean field; if any weeds are present at planting, controlling them will be an added challenge all season; 2) layering your residuals at planting and three to four weeks following planting (depending on rainfall and temperatures during that time period) and avoiding any gaps in residual activity; 3) being aware of the potential and scouting for wireworms in no-till fields, especially those with a cover crop, and being prepared to apply pyrethroids at planting to control; and 4) monitoring and preparing for any thrips infestation immediately following emergence. 

Seed treatment insecticides, foliar insecticides and varieties with ThryvOn technology (see a recently published Texas A&M AgriLife factsheet on ThryvOn by Drs. Suhas Vyavhare and David Kerns at: https://lubbock.tamu.edu/files/2024/02/ENTO-PU-223-ThryvOn-Cotton_fn.pdf) are very effective at controlling populations. We are fortunate in our region (especially the areas south of Lubbock) that thrips are not always at economic threshold; however, our more northern regions (Lubbock northward and throughout the panhandle) regularly have thrips pressure high enough to warrant control measures and avoid delays in maturity.

Growers throughout the high plains should keep an eye out for our Texas A&M AgriLife Replicated Agronomic Cotton Evaluations (RACE) trials throughout the region this season. My program will have 19 locations from Bailey County to Borden County, and Dr. Jourdan Bell will have six locations throughout the panhandle area. This will give growers many opportunities to compare varieties’ emergence, growth and development, and ultimately, yield and fiber quality. These locations will be well-marked and plot plans will be available both online via QR codes and hardcopies onsite. And thanks in advance to all our grower cooperators, participating seed companies, Plains Cotton Growers and the Texas State Support Program through Cotton, Inc. who all make this program available and successful! ken.lege@ag.tamu.edu 

MISSISSIPPI | Brian Pieralisi

Cotton acres in Mississippi are expected to increase by 28% compared to 2023. With cotton prices a bit higher and other row-crop prices lower than they were this time last year, Mississippi is projected to plant 500,000 acres. As I write this, spring is ahead of schedule again, similar to last year; thus, conditions are lining up for early planting dates. However, a cold snap is never out of the question until after the first two weeks of May. Growers should focus on management tactics within their control and take advantage of any favorable planting opportunities.

Thrips are the primary early season pest affecting Mississippi cotton. Over the past several years, thrips pressure has been unusually high causing multiple applications in some cases. This can likely be attributed to slow-growing cotton met with environmental conditions favorable for this pest. Typically, by the three- to four-leaf stage, cotton plants are past the most susceptible stage for economic injury or delays in maturity. However, a sound management plan is in order to mitigate injuries from thrips. ThryvOn cotton will comprise more of our acres than in 2023. Currently, ThryvOn cotton effectively manages thrips, allowing for rapid progression through the developmental stages under favorable growing conditions and adequate heat unit accumulation.

Early season thrips management typically consists of the following: imidacloprid-treated seed or in-furrow treatments followed by foliar applications. In-furrow treatments of 1.1 pounds of acephate or 8 ounces of imidacloprid should be directed on or below the seed for most effective control. Under high reniform nematode populations, 3.5 to 5 pounds of aldicarb or planting a nematode-tolerant variety is a good management strategy. Most current cotton varieties are pretreated with recommended fungicides; however, using in-furrow insecticides increases susceptibility to cotton seedling diseases. So, be sure to plant seeds treated with a recommended fungicide.

Lastly, most cotton grown in Mississippi is conventionally tilled and cutworms are not an issue. However, in both cover-cropped and no-till acres, cutworms could establish on existing vegetation. Cover crops should be terminated at least three weeks prior to planting to avoid risks associated with stand reduction.  If vegetation is not terminated three weeks prior to planting, a pyrethroid should be used at planting, which will protect early season cotton seedlings from stand reductions. bkp4@msstate.edu

ALABAMA | Steve M. Brown

In the 1977 book The World’s Worst Weeds: Distribution and Biology, the authors listed purple nutsedge as the No. 1, “Mr. Weed of the World.” Other common species in their most troublesome list included bermudagrass, barnyardgrass, junglerice, goosegrass, johnsongrass, common purslane, common lambsquarters, large crabgrass, field bindweed, wild oats, smooth pigweed, spiny pigweed and yellow nutsedge.

In addition to geography, cultural practices and herbicide chemistries have a profound impact on weed spectrum. For example, I remember a year when a farmer fallowed a field to fight bermudagrass with tillage. Obviously, this preceded the introduction of the graminicides (Poast, Fusilade, Select, etc.) and fall, post-harvest applications of Roundup. And how many weed scientists’ careers were built on programs targeting sicklepod, a weed now routinely managed with glyphosate systems?

For the Lower Southeast, Palmer amaranth remains a huge challenge. Millions of dollars have been spent fighting this small-seeded, broadleaf annual. Aggressive programs that target troublesome weeds generally provide broad-spectrum control…until a new “most troublesome” pest emerges.

Keys to successful management of problem weeds include starting clean and staying clean. Simple to state from the office, shop or pickup but not easy to accomplish. Staying clean involves repeated applications of residuals — “layering” as some refer to it — and timely intervention with post herbicides. The oft-repeated message — timing is critical — always applies.

Whether the challenge is Palmer amaranth, morningglories or you-name-it, timeliness makes a huge difference in herbicide performance, especially for postemergence treatments. Liberty (glufosinate), which is critical to our management programs, is a good but finicky tool, even in tank mixtures. A little stress, reduced humidity or low light can alter its performance, especially if weeds exceed a few inches. There can be drastic differences in control of one to three-inch Palmer amaranth as compared to those that are five to seven inches. Same effort, same product(s) but vastly dissimilar results.

May is crunch time. Planting. Thrips control. Early season weed control. To borrow from fertilizer doctrine, maximizing inputs requires using the right product(s) at the right rate at the right time. cottonbrown@auburn.edu

GEORGIA | Camp Hand

By the time everyone is reading this, I hope we will have a good bit of cotton planted in Georgia. As I write April 5, we have just started planting plots on the station here in Tifton, with intentions to really start getting after it in a couple of weeks.

When most of you read this in the beginning and middle of May, you will have already made decisions for many early season pests — thrips, seedling disease, nematodes and weed management. As many of you are likely moving into early postemergence herbicide applications, I would urge you to keep in mind the lessons learned from “Using Pesticides Wisely” trainings this spring. I went to the training April 3 here in Tifton and learned a lot of good stuff. But the main take away for me from the training was this: the future of pesticide use across the board hinges on us as applicators. We bear the burden of responsibility, so let’s use these tools correctly so we can keep them in the toolbox long term.

The other early season pest that many of my colleagues likely won’t mention is something I talked about this past winter a lot. If you’re guessing white-tailed deer, you’d be guessing correctly. Although there isn’t an “official” recommendation on how to manage this pest in a cotton crop, I would greatly urge growers to listen to Episode 37 of “All About the Pod” from the University of Georgia peanut team. Here is the link: bit.ly/deerpestmgt

In this episode, Brian Vickery with Georgia’s Department of Natural Resources discusses the use of depredation permits and how to more effectively utilize that tool.

As always, your local UGA county Extension agent and specialists are here to help! Reach out if you have any questions. camphand@uga.edu