Monday, September 20, 2021

Get On Top Of Early Season Pests

Bob Hutmacher
Bob Hutmacher
California

San Joaquin Valley growers are again in the unfortunate position of having to deal with the after-effects of below-normal rainfall and a reduced snowpack. We already know of many planned reductions in irrigation district water allocations that may impact cotton management choices for this year.

Many if not most SJV cotton fields have been planted during a warm weather window that started the last part of March, extending into the first week of April. With generally dry, warm days and cool but not cold nights during the planting cycle, plus lack of rain to wet the soils after planting, expectations are this will at least be a below-average year in terms of seedling disease losses.

The relatively early plantings, if not accompanied by poor weather later in April or May, could be fortunate in terms of an earlier start to the growing season. The early start to the planting season sometimes helps us out by:

• Allowing plants to develop a good root system and strong vegetative structures during cooler spring weather.

• Earlier square and flower development that might avoid some of the mid-summer hot spells that sometimes affect fruit retention.

If we can get plants to hold early developing squares and bolls, it might also promote earliness that could allow an earlier termination of irrigation and even reduce crop water use.

Some years earlier, cotton plantings could be more susceptible to damage from western flower thrips, false chinch bugs, etc. coming out of neighboring crops or from lygus coming out of winter weeds. But I would expect fewer problems this year since it has been warm and dry for an extended period.

However, increases in tree and vine plantings, plus scattered plantings of other annuals such as safflower, corn and sorghum, plus a mix of vegetable crops means that cotton plantings are in competition for limited water supplies. Cotton also has to co-exist near various “neighboring crops” with some different management priorities, or even next to fallow fields. This situation may warrant extra attention later as cotton starts squaring.

With these neighboring crops, the mix of pests and beneficial insects you end up with and some treatment options may require adjustments going forward.

In a year like this with limited and expensive water, pests that threaten early fruit set and yield potential can be a significant threat. A quick, good fruit set can offer earliness and less of a need for an extended irrigation season required for a late-developing “top crop.” rbhutmacher@ucdavis.edu

Randy Norton
Randy Norton
Arizona

Seedling cotton can be found around the entire state. Decisions are now being made regarding the protection of the young plant and ensuring it has the resources it needs to thrive.

Early season insect pressure can sometimes be significant. Monitoring for damaging populations of insects such as thrips, false chinch bug and flea beetle among others is important in protecting the early crop.

There are times where the need for control measures is warranted for early season insect pressure. But be judicious in the use of selective chemistries wherever possible to target the pests while attempting to preserve any beneficials that are present in your fields.

Early season nutrient management is also important in maintaining plant health. Ensuring that the crop has sufficient resources to maintain healthy growth is critical. Timing of fertilizer nutrient applications is important to maximize use efficiency. Remember that nitrogen is very mobile in the soil-plant-atmosphere system and can be subjected to loss from the system.

Soil N uptake begins to increase dramatically near first square and reaches a maximum at peak bloom. To maximize its uptake efficiency, it is best to apply needed fertilizer nitrogen during the first square window to peak bloom. This is not necessarily the case with either potassium or phosphorus. The dynamics of these additional two macro-nutrients are quite different than N.

This forum does not provide space to discuss these in detail, but additional information regarding the management of all nutrients and other topics can be found at cals.arizona.edu/crops. rnorton@cals.arizona.edu

stu duncan
Stu Duncan,
Kansas

With the recommended time for cotton planting rapidly approaching, there are a couple of early season tasks that should be completed. To give the crop a competitive advantage, it is important to plant into a weed-free seedbed. There is still time to apply a good burndown if that has not already been done.

The goal is to start clean and stay clean. If wind and/or rain has delayed these operations, most burndown herbicides may be applied with a preplant herbicide application. Be sure to check the labels for possible antagonism between products. Preplant and preemergence herbicide applications should be designed to include a good residual herbicide(s) for problem weeds previously identified in your fields.

Once your crop is in the ground and the nearby wheat fields begin to ripen and dry down, be on guard for thrips infestations. New traits are coming available for thrips resistance in cottonseed, but may not be available yet in varieties adapted to your area.

Kansas growers must keep in mind that our crop cannot afford to experience development delays, and thrips historically have been the first insect pest for which to be on guard. sduncan@ksu.edu

seth byrd
Seth Byrd,
Oklahoma

As of mid-April, the cotton-producing areas of Oklahoma remain fairly dry, although there are some chances for precipitation prior to the start of May in some forecasts. While moisture and temperature are typically going to be the focus as we enter the planting season, early season pest control will also be on every producer’s mind.

The residual herbicide products we typically use at planting require some method of incorporation. Because any tillage operation after planting is a rare occurrence in most current production systems in Oklahoma, this means we’ll be relying on rainfall or overhead irrigation.

Dry conditions in some areas of the state have slowed weed emergence. In others, applications may have already been made to prevent weeds from becoming too large to effectively control at planting.

The two primary principals we’ve likely all heard dozens of times but still ring true are to 1) start clean, meaning to eliminate any weeds present at planting, and; 2) overlap residuals.

Be sure to understand the window of effectiveness of the residual herbicide you use at planting and have a game plan in mind on what you’re using next and when you’re going to apply it to maintain effective residual control. Cotton isn’t a competitive crop in the seedling stage, so competition for water and other resources must be minimized to optimize growth and prevent delayed growth.

Beyond weeds, thrips control will also be key to ensure rapid growth is achieved early in the season. If you’re in an area where thrips pressure is common, or you have surrounding host crops that might increase the risk of thrips activity, be sure to address this threat.

The first step is to have a scout in the field to provide timely updates of thrips pressure.

For control, whether it’s through seed treatment, in-furrow application or over-spray after emergence, it’s key to understand the window of control of whatever method you’ve selected. In areas or years of heavy pressure, a combination of seed treatment or in-furrow application plus an overspray may be required.

For more information on planting and early season growth, refer to our factsheet at https://bit.ly/3da7ddO. seth.byrd@okstate.edu

ben mcknight
Ben McKnight
Texas A&M

Currently, any substantial relief from drought conditions has been scarce across much of Texas. Some of the earliest planted cotton in the Lower Rio Grande Valley is approaching the four true-leaf stage as I write this the first week of April.

The majority of the crop in the LRGV and Coastal Bend is in the cotyledon- to two-leaf stage. Insect pest pressure has been light so far in the LRGV with some isolated, below-threshold reports of thrips, cotton aphids, and spider mites.

Growers in the Upper Gulf Coast are busy getting the cotton crop planted into remaining soil moisture ahead of projected 90 degree high temperatures in the coming days. In the next week or so, leading up to the middle part of April, the majority of cotton acres in the Upper Gulf Coast will be in the ground awaiting some much needed rainfall.

Producers in the Blacklands have wrapped up planting grain crops and will now shift their attention to the cotton acres for the remainder of April. With the current long-term weather forecast, growers are capitalizing on current soil moisture to get the crop out of the ground. Land preparation in the Rolling Plains is in full swing ahead of planting in mid-May to early-June.

Seed and in-furrow treatment for thrips have benefits and provide control until the one- to two-leaf cotton growth stage under most circumstances. As the activity from seed and in-furrow treatments begins to decrease, timely follow-up chemical applications for thrips may be needed depending on pressure and environmental conditions. Be aware of economic thresholds and avoid spraying ahead of threshold level infestations as this increases the potential of flaring spider mite populations.

For more information on insect pests and economic thresholds of each pest in cotton visit https://cottonbugs.tamu.edu. bmcknight@tamu.edu

Murilo Maeda
Murilo Maeda
Texas A&M

By the time you receive this issue of Cotton Farming, it is likely planting has already started in the Texas High Plains. Weather is unusually warm for this time of year, and moisture is lacking for most of the region. Despite being blessed with some rainfall, warm and windy days have prevailed.

Some places have limited subsoil moisture from recent rains, but most will need supplementation, either from rain or irrigation for adequate crop establishment.

Once again, continue to be vigilant on the input front. Despite having already chosen what to plant, when to plant is the next logical question that can have season-long implications. We have no control on the weather and a narrow planting window for some. Always strive for good planting conditions whenever possible.

With moisture being the obvious overriding factor here, aim for soil temperatures greater than 65 degrees Fahrenheit and 25 or more heat units accumulated within five days of planting. Our colleagues at North Carolina State University have a handy online tool to help you monitor heat unit accumulation for your location based on the National Weather Service forecast.

You can find it here (https://products.climate.ncsu.edu/ag/cotton-planting/). I also encourage you to obtain warm and cool germination test results from your seed company and/or seed retailer. These are lot-specific and can help you make an informed decision if faced with unfavorable conditions at planting.

Adding those two numbers together (warm and cool test values) should give you the vigor index for that lot. If higher than 160, that seed has an excellent vigor index, conversely 120 or less would indicate a poor vigor index.

Faced with less than adequate conditions at planting, you may prioritize planting a higher vigor index seed first as you wait for conditions to (hopefully) improve before seeding the lower vigor index seed.

The goal is to give your crop a better chance to get off to a good start. Be mindful of farm equipment moving around as planting activity picks up, and as always, stay safe out there. mmaeda@ag.tamu.edu

matt foster
Matt Foster,
Louisiana

According to the US. Department of Agriculture National Agricultural Statistics Service, cotton acreage intentions in Louisiana are at 120,000 acres, down 29% from the 170,000 acres planted last year.

Most cotton producing areas in the state experienced wet field conditions during March, and more rainfall is predicted as the optimal planting window approaches in mid-April. Cotton planting should begin soon, depending on the field conditions.

Thrips are a major early season pest of seedling cotton in Louisiana and throughout the Cotton Belt. Tobacco thrips are the most common species on the state’s cotton. Research has shown that severe thrips infestations can reduce yield by 200-300 pounds of lint per acre.

Cotton is most susceptible to thrips injury between emergence and the fourth true-leaf stage due to the slow development of the terminal bud. Therefore, it is important for producers to manage thrips during this critical growth stage. Cotton seedlings injured from thrips may exhibit tattered and crinkled leaves that curl upward and fail to properly expand. Keep in mind that injury from sandblasting and preemergence herbicides can mimic thrips injury.

Management options include insecticide seed treatments, in-furrow applications and foliar sprays. Insecticide seed treatments are the most popular.

Currently, acephate and neonicotinoids are the only two seed treatment options. The two most common neonicotinoids are imidacloprid and thiamethoxam and are offered alone or in combination with nematicides. LSU AgCenter entomologists do not recommend the use of thiamethoxam alone to manage thrips in cotton due to development of tobacco thrips resistance.

At planting in-furrow insecticide options include imidacloprid, acephate or AgLogic (aldicarb). Foliar rescue sprays may be necessary under certain conditions, but they should not be the only tool used to manage thrips. The decision to use a foliar insecticide for thrips control should be based on scouting.

The presence of immature thrips indicates the insecticide seed treatment has broken down and reproduction is occurring. Foliar insecticide options include acephate, Bidrin, Radiant, dimethoate or Intrepid Edge. Implementing a good thrips management plan will help ensure your cotton gets off to an excellent start. mfoster@agcenter.lsu.edu

Bill Robertson, University of Arkansas
Bill Robertson,
Arkansas

The Prospective Plantings report released in March by the U.S. Department of Agriculture-National Agricultural Statistics Service estimated cotton plantings in Arkansas at 490,000 acres, down 7% from the 525,000 acres planted last year. This estimate is in line with the National Cotton Council estimate released earlier this year.

Oftentimes, we feel the need to plant as early as possible. Our data shows we can still optimize yields with planting delays. Our optimum planting window in southeast Arkansas historically includes dates ranging from April 20-30. Locations at and north of Interstate 40 see their optimum window shifting back as late as May 9.

Weather varies from year to year. However, the most important thing is to do it right the first time.

thrips damage
Thrips damage on cotton

When pushing the limits on earlier-than-advised planting, replanting is sometimes necessary. When planting into cold soils, it is imperative to use the highest quality seed. As seed size decreases, seed quality becomes more critical when planting in marginal conditions.

When determining if replanting is necessary, many factors should be considered. First, it is important to evaluate the current stand of plants that will survive. Establishing the occurrence of skips greater than 3 feet in length, especially when this occurs simultaneously in adjacent rows, is critical. Cotton’s ability to adapt and maintain yield potential at lower plant populations is often underestimated. If the decision to replant is difficult, it is usually best to keep the stand.

The period from planting to first square is a critical time for the cotton plant. While water and nutritional requirements for the plant are low, cotton is not a very good competitor. Allowing weeds or other pests overcome pre-squaring cotton will affect yield potential.

It is easy to sometime overlook the importance of early season weed control when we have the tools to clean up a weedy mess down the road. Place high priority on early season weed management to avoid losing yield potential early in the season that is difficult to regain and can be very costly. brobertson@uaex.edu

brian pieralisi
Brian Pieralisi,
Mississippi

December cotton futures have been trading a lot higher in recent months, which makes penciling in a profit much easier than this time last year. As I write this on April 5, cotton prices are just south of 80 cents with greater profit potential than previous years. Mississippi cotton is projected at 500,000 acres, down 5% from last year. Despite favorable cotton prices, corn and soybean will likely be planted on the voided acres.

Thrips pressure was unusually high in 2020, which triggered multiple foliar applications to avoid delays in maturity through June. As we move forward in 2021, I recommend insecticidal seed treatments or in-furrow applications to help mitigate this pest.

Cotton is most vulnerable at the three- to four-leaf stage, which often times requires an additional foliar application. Acephate and imidicloprid are good seed treatment options as well as in furrow. Aldicarb in-furrow provides excellent control if you are set up for granular applications. However, this is a bit more expensive and could be more justifiable if you have a nematode problem as well.

I suggest focusing on timely nitrogen applications. Regardless of your application method, it is critical to have nitrogen applied just prior to first bloom. Nitrogen use intensifies tremendously at this point, making it critical to have a full supply available as nitrogen demand increases.

Depending on irrigation availability or impending weather, I recommend having a fully charged soil moisture profile going into bloom with all nitrogen applied. This will mitigate plant stress and help avoid excessive fruit abortion, which will hopefully translate into greater boll retention later in the season. Also, late season nitrogen deficiency is not a bad thing.

If properly applied, late season nitrogen deficiency symptomology low in the canopy means all nitrogen is relocating to yield components. Ultimately, this will reduce late-season diseases like boll rot, reduce late season insect pests and increase defoliation success. bkp4@msstate.edu

STEVE BROWN, alabama
Steve M. Brown,
Alabama

Although I’ve evaluated seedling vigor of varieties for years, experience doesn’t give me confidence about my ratings. I tend to be very critical, and most of what I assess is confounded by thrips injury — leaves ragged, plants stunted and terminals sometimes blackened. What I hope to see, but rarely do, is green, smooth leaves, vigorous stalks and healthy terminals.

Maybe I was spoiled by Temik in-furrow and the early years of Roundup Ready. The latter meant less pre herbicide injury and with the former, cotton jumped out of the ground. Such a wimpy starter but STRONG finisher like DP 555 BR might not have been possible without both.

Yes, more vigorous varieties tend to grow through problems more readily. Still, I want to see cotton that’s “getting it;” in more sophisticated terms, seedlings with strong plant health.

Ah, “plant health,” what a popular term, one that gets all the press … and grants. Like “sustainable.” In a recent interview, a candidate discussed sustainability in big and broad terms. I had to ask, “How do you think an Alabama farmer defines sustainability?” I was looking for PROFITability. Excuse me for chasing (and whacking) a rabbit.

A couple of years ago I walked into a no-till field that had been planted in mid-May. It had considerable surface residue. Cotton was about 21/2 weeks post-plant and three days earlier had been sprayed with a herbicide and insecticide mix. It was the prettiest young field I’d seen in years.

Several things contributed to the goodness of that stand. It was planted under good conditions. Emergence and early growth were rapid. Old corn stalks probably reduced thrips pressure, and the insecticide treatment was out front, ahead of significant thrips feeding.

While you can’t plant every field under great conditions and cover crops may not be an option, being out front on thrips pays dividends. If heavy pressure is anticipated — and you can check this with the Thrips Infestation Predictor for Cotton at https://climate.ncsu.edu/cottonTIP — you may benefit from an early foliar treatment. Sooner rather than later. A common mistake is to wait until damage is easily recognized, which means you should have intervened days earlier.  cottonbrown@auburn.edu

David Wright, Florida
David Wright,
Florida

Make wise decisions on pest management at planting so you don’t get behind in weed and insect management and spend more than necessary catching up.

Most of our cotton is grown using conservation tillage and planted into cover crops or winter fallow weeds, which need to be killed two to four weeks ahead of planting. At planting, herbicides should include something to kill emerging weeds and residuals to control weeds for the first few weeks of growth.
Some of our growers use low rates of starter fertilizer in a 2-inch-by-2-inch placement during planting.

Phosphorus can be applied at that time with no more than 20-30 pounds of nitrogen per acre. We do not recommend in-furrow application of fertilizer even at low rates as it can reduce population. The 2-inch-by-2-inch fertilizer is adequate to help cotton get off to an early start.

Cotton seldom responds to starter fertilizer except for early growth, while yield is often similar without starter fertilizer.

Our highest yielding cotton always follows winter grazing using less irrigation and nutrients due to recycled nutrients. This means two to four times more nitrates and two times more potassium in the root zone following cattle and enhancement of cotton roots versus non-grazed cover crops. wright@ufl.edu

camp hand
Camp Hand,
Georgia

In Georgia, this time of year is off to the races concerning planting. Although some cotton has been planted at this point, it will continue to be planted for a while because of our wide planting window. Here are a few early season pest management thoughts:

• If you have yet to finish planting your cotton, you should be thinking about nematodes. For many cotton producers in southern Georgia, our winter may not have been severe enough to knock nematode populations back substantially. Conditions may have also allowed mowed cotton stalks to survive, which can feed the nematodes.

As an example, Jeremy Kichler (Colquitt County Extension agent) took nematode samples from last year’s research plots (susceptible variety) on March 11. Root-knot nematode counts were already four times the fall threshold value. You get one good shot to punish nematodes. Once that furrow is closed, your management options are severely limited.

• By now, everyone spraying dicamba or 2,4-D in-crop should have attended a “Using Pesticides Wisely” training conducted by Dr. Stanley Culpepper. This means you now know he and his team have confirmed PPO-resistant Palmer amaranth in Georgia. Georgia growers must continue properly stewarding herbicides to remain sustainable.

Culpepper’s weed management recommendations for cotton can be found at https://bit.ly/3giL0wb. Highlights from an early season standpoint include starting weed free (using tillage, cover crops or burndown herbicides), apply two mechanisms of action pre, and sequential post applications with the first one coming roughly two weeks after pre applications, and the second one roughly two weeks later.

• Thrips are the main insect pest for us early in the season. At-plant insecticides must be used to manage this pest, with consistent positive yield responses observed. Follow-up applications may be necessary. The threshold for those applications is two to three thrips per plant with immatures present. Cotton planted after May 10 or planted into a cover crop will typically have less thrips pressure.

If you have any questions, your local UGA county agents, along with myself and other specialists, are here to help. camphand@uga.edu

Tyson Raper, Tennessee
Tyson Raper,
Tennessee

Dr. Scott Stewart has been keeping a close eye on foliar applications of acephate to control thrips for quite some time. Unfortunately, he began noticing a slip in efficacy with our standard rate several years back.

In Tennessee, cool, wet conditions can lengthen the amount of time our earliest planted cotton remains susceptible to thrips. As a result, we use imidacloprid as our go-to seed treatment and plan to make a foliar application at the one to two true-leaf stage.

A considerable slip in efficacy has been captured for several consecutive years in Jackson, and it now appears the trend is showing up in other locations beyond Tennessee. The current recommendation to overcome this reduction in efficacy is to either increase the rate of acephate or consider another product like Bidrin or Intrepid Edge.

For more information from Stewart, find his recent 2021 Cotton Focus Video Series presentation on the topic online at news.utcrops.com. traper@utk.edu

Guy Collins, North Carolina
Guy Collins,
North Carolina

By the time this is read, planting should be underway. Let’s hope and pray our planting season brings weather noticeably better than what we experienced last year.

Hopefully, growers have used the NCDA Cotton Seed Quality Database to document both the warm and cool germ for each lot number of seed they purchased and use that to make the best planting decisions possible. This database, along with the NCSU Cotton Planting Conditions Calculator, can be found on our NCSU Cotton Extension Portal website, https://cotton.ces.ncsu.edu/, under “Calculators & Decision Aids” on the left-side toolbar.

The NCSU Cotton Planting Conditions Calculator should probably be used daily, both in early morning and again in the evening. The calculator provides real-time recommendations based on the National Weather Service forecasts, which can change drastically in a short time during some years.

Additionally, growers can select a specific farm or field on the map to calculate recommendations, which include a five-day heat unit forecast and rating, for the day it is accessed and for the day following. During periods rated as “poor,” cotton shouldn’t be planted, regardless of seed quality.

During periods rated as “adequate” or “marginal,” pay close attention to cool germ and plant the highest cool germ lots, as well the largest seed possible. Growers may also want to adjust their seeding rates according to these conditions and the cool germ of the lot to be planted.

We are always in a hurry to plant every day that brings good weather, with a favorable five-day forecast. Usually, we continue planting until it’s completed, then we start to evaluate the planted crop. Let’s not forget timely scouting is necessary as soon as the crop emerges.

Growers should use the Thrips Infestation Predictor, also on our website, to target scouting and possible treatment to particular fields. Remembering that the most important time to treat is when the first true leaf appears between the cotyledons.

Scouting for weed emergence or efficacy of your residual herbicide program is essential during this same time. There is a lot of value to being timely when action is needed. guy_collins@ncsu.edu

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