Alabama Cotton Insect Situation: June 16th, 2022

We still have some thrips going in spots here and there, but we are mostly through that window. Plant bugs and spider mites are the biggest calls and reports that we are getting.

As more cotton is starting to square across the state, we are receiving more reports of adult plant bugs moving into fields. Remember our thresholds are 2 adults per 25 sweeps (8 in 100 sweeps) or 80% square retention in the upper 2 or 3 nodes of the plant.

One important thing keep in mind is that thresholds are more of a guideline than a hard and fast rule. The proper term is “economic threshold” which obviously means economics play a role (both commodity and input prices). Due to the fluctuation and variations of prices, we don’t change our thresholds each year, but we can adjust a little bit “on the fly” if we need to. With cotton prices hovering over a dollar, we can afford to be a little more aggressive with insect management. This is because even though the insects are “eating the same amount of cotton” they are eating “more money” because that cotton is worth more. This is not to say that scouting and thresholds aren’t important in years with high prices, an application with no insects in the field is still a waste, just that pulling the trigger a little sooner may provide a higher return. Of course, in years where prices are low, the opposite is true.

Early spider mite symptoms

We got some storms across Alabama yesterday, and that may help the spider mite situation a little bit, but I wouldn’t bet on it. With the temperatures across the state right now and projected to be even hotter next week, every insecticide application should consider spider mites. We are in a situation where they could blow up quick. I am not saying don’t treat plant bugs if you have economic infestations for fear of spider mites but try to choose something less likely to flare them. Our threshold is to treat when 30% or more of plants are infested with spider mites and damage is evident. Sometimes we may watch the forecast and see if an imminent rain can help us before we make an application. I am not sure I would do that with the current outlook. I think being a little more proactive on these building populations with upper 90’s and even into the 100’s temperatures impending would be prudent.

Mating southern green stink bugs in corn

I also want to briefly mention stink bugs. We have been in corn fields in central and SE Alabama this week collecting corn earworms for Bt resistance monitoring. There is currently a ton of adult stink bugs in corn fields that are mating, and some nymphs are beginning to emerge as well. Corn is the perfect trap crop for stink bugs and cotton. A well-timed application will help corn and cotton as well. The best time to spray is at tassel, while the ears are forming, but stink bugs can damage corn through the R2 (blister) stage. Most labeled pyrethroids provide good control. If you haven’t, consider making an application in corn, it will help that crop and likely relive some pressure in cotton later in the year as well. For more information on managing stink bugs in corn, watch this video (link) with Eddie McGriff and Dr. Katelyn Kesheimer.  

We will also give a reminder that we have two more scout schools (link) this coming week. We will be at the TN Valley REC in Belle Mina on Tuesday the 21^st with registration starting at 8 and the program beginning at 8:30. We will also be in Centre at McCord’s Fire Station #1 on Thursday the 23^rd. That program will begin at 10 am.

As always, if we can ever be of any help, please let us know.

Alabama Cotton Insect Situation: June 6, 2022

Things were pretty quiet last week, but the Alabama Cotton Insect Situation seems to be picking back up this week. We have already gotten a few calls about threshold levels of adult plant bugs in squaring cotton in in Central and SW Alabama. If you remember last year, we had a big migration of adult plant bugs into cotton fields statewide around June the 15^th. At this point, adults are moving into our oldest cotton (mid-April to first week of May) that is starting to put on squares. So, most of our fields aren’t at risk yet, but keying in on fields that are squaring is important. Much of the fleabane across the state has already or is starting to play out. This means plant bugs are looking for somewhere to go and a cotton field that is starting to square is a good place for them to settle in. Reports out of the TN Valley and NE Alabama are that not much cotton is squaring, and no threshold levels of plant bugs have  been observed.

Adult Tarnished Plant Bug

With input and cotton prices where they are, it’s going to be important to scout fields and be prepared to treat when necessary. Prior to bloom, our thresholds are 2 adult plant bugs per 25 sweeps or 80% square retention in the upper 2-3 nodes. One thing to keep in mind is that we may scout a field with high square retention, but also high numbers of plant bugs. That may mean that the bugs just moved into the field and that squares that were fed on haven’t yet had time to abort. That’s why we like to use these thresholds as an either/or and a both/and. In other words, if you hit one of the thresholds but not the other, we should go ahead and trigger a spray.

In terms of recommendations, we like to manage migrating adults as economically as possible, because there is always the potential for more to move in a few days after a spray. Unfortunately, nothing will provide much residual control of migrating adult plant bugs. I have heard some reports that some of our “June go-to’” products are hard to get. We have some options, such as imidacloprid (highest labeled rate), Centric (1.5-2oz), acephate (8-10oz) and depending on resistance in your region, bifenthrin (6.4oz). Keep in mind that per the label, Bidrin cannot be applied between pinhead square and first bloom.

Another thing to remember is that square retention is a good way to evaluate the efficacy of an insecticide on migrating adults. If you come back to a field 5 or 7 days after a spray and find as many or more plant bugs, good square retention will tell you your spray worked, and more bugs have moved into the field.

We should be through the thrips window for much of our cotton, some fields, particularly in north Alabama, may still need to be watched. As a general rule, we don’t see much value in spray cotton beyond the 4^th true leaf stage, but we have seen some fields this year that would very likely benefit from a spray at the 5^th or 6^th leaf.

Early spider mite symptoms on leaves

The last thing I will mention is that we observed spider mites in a field in central Alabama today. It has been an interesting start to the season variable weather, most too dry and some too wet at times. These mites had likely been building on some weeds that were in the field and have moved into the cotton after a herbicide application went out. In dry areas, spider mites are another thing to consider when making insecticide application decisions. Hopefully the chances of rain across the state this week will materialize so we can get some reprieve and help get this cotton crop off and running.

The 63rd Alabama Cotton Scouting School is coming up. This year we have our 3 traditional locations: Tuesday, June 14^th in Autaugaville, Wednesday June 15^th in Headland and Tuesday, June 21^st in Belle Mina. We will also have an in-season scouting update in Centre on June 23^rd and a late season scouting update in Southeast Alabama in August. More information can be found here.

As always, if we can ever be of any help, please let us know.

Alabama Cotton Insect Situation: May 17, 2022

Phone calls have started pick up over the past 7 to 10 days and grasshoppers and thrips tend to be the biggest insect issues we are hearing about. 

Grasshoppers are primarily a concern in reduced or no-till fields and in lighter, well-drained soils. Unfortunately, we don’t have any thresholds for grasshoppers as damage is sporadic and varies from field to field and year to year. The decision to treat is often based professional judgement or the level of risk a farmer is willing to take. At this point in the year, we are dealing with mixed populations and a fair number of adults in the field. The presence of adults (or winged grasshoppers) is important to note, because they are more difficult to control than the immatures (or wingless grasshoppers). Pyrethroids provide spotty control of adults and our general recommendation is up to 3/4 of a pound of acephate.

Most of the calls on thrips we have been getting revolve around making supplemental sprays in dry areas or in fields with historic spider mite issues. In these situations, we try to use insecticides that are less likely to flare mites, such as Intrepid Edge (3 oz/A) or Bidrin (3.2 oz/A). As far as thresholds, we recommend 1-2 adult thrips (dark brown or black) per plant with immatures present. The immatures are smaller and a yellowish color. Presence of immatures tells us that our at-plant insecticides aren’t providing control. You can sample by using a white Styrofoam cup (or something similar) and knocking plants into the cup then count the number of thrips found. Injury is characterized by crinkling of leaves. This is because thrips are feeding on new leaves still in the furl, which brings up an important point. When evaluating foliar sprays for thrips, often you cannot tell how good a spray did until the next true leaf has opened. In other words, if you spray cotton with one true leaf and the second still in the furl, the second may already be damaged, so the third true leaf would more likely show the protection from the spray. Cotton seedlings are most susceptible to thrips injury through the 4-5^th true leaf stage and when not growing rapidly.

Late April planted cotton with no at-plant thrips treatment near Tallassee, AL in 2022.

Alabama is all over the board in terms of growing conditions and soil moisture. We have some fields that had enough moisture to germinate seeds but not enough to establish a stand, while we have also gotten several calls about slugs in soybeans. Storms seem to be so localized that its hard to say where we are and are not getting rains. Hopefully the weather will turn around soon and we can get some good growing conditions and kick the crop off.

As always, if we can ever be of any help, please don’t hesitate to reach out and lets us know. 

Cotton Thrips Models for Alabama in 2022 (April 22nd)

Generally speaking, Alabama cotton experienced higher than "normal" thrips pressure in later (mid-May+) planted cotton in 2021. According the Cotton Thrips Model (link), 2022 is setting up to be more of a "normal" year in central and south Alabama, with later planting cotton being at a higher risk in north Alabama. On April 21st, we ran the model for a project planting date of May 2nd across south, central and north Alabama. Predictions were fairly consistent across each region when moving east to west. Typically when we talk about risks from the model, we just mention one chart, showing the in-season risk for the given location. However, this year we also must talk about the chart giving predictions compared to previous years to best understand the big picture.

South Alabama

We ran models in south Alabama (Henry, Monroe, Escambia and Baldwin counties), and each model was nearly exactly the same. Thrips pressure in south Alabama is expected to be heavier in April through around the 2nd week of May. Below is the chart print out from Henry County, but remember it represents most of south Alabama.

In-season (top) risk of thrips injury in South Alabama in 2022. Comparison of 2022 vs previous 5 years (bottom) in the same area. (Chart showing Henry County, AL)

Central Alabama 

South of Birmingham

Models across central Alabama (Marengo, Autauga, Elmore, Lee counties) show the peak of thrips injury being in cotton planted in mid-April, with elevated risks through mid-May.

In-season (top) risk of thrips injury in South Central Alabama in 2022. Comparison of 2022 vs previous 5 years (bottom) in the same area. (Chart showing Autauga County, AL)

Birmingham and North

The model shows a different prediction for cotton in central Alabama beginning around the Birmingham latitude. Models in Pickens, Tuscaloosa, and Talladega counties show cotton planted through mid-May is at the highest risk, with elevated risk through the end of May.

In-season (top) risk of thrips injury in North Central Alabama in 2022. Comparison of 2022 vs previous 5 years (bottom) in the same area. (Chart showing Talladega County, AL)

Tennessee Valley and Northeast

Models in the Tennessee Valley (Limestone, Madison and Colbert counties) and northeast Alabama (Cherokee, Dekalb and Blount counties) were consistent and showed that overall thrips pressure is expected to be high across the regions. Cotton planted in May is at the highest risk of injury but earlier planted cotton is at a higher risk than in 2021.

In-season (top) risk of thrips injury in North Alabama in 2022. Comparison of 2022 vs previous 5 years (bottom) in the same area. (Chart showing Limestone County, AL)

Take Home Points

These models give us a good prediction of what thrips pressure may be this season and relative to other seasons. The model should not be used as a guide for when to plant, but rather what to expect when we do plant. By using the model, we can have a good idea for which fields may need a foliar spray to supplement seed treatments and which fields may not. The model predictions can change as unexpected weather events occur, so keep running them a couple of days before and after planting to make sure nothing has changed.

We will update the blog over the next couple of weeks to provide any changes that may happen.

Thinking About Thrips in 2022

Insect management is different from all other aspects of cotton production. With most insect pests, the situation changes year to year, week to week, and sometimes field to field. However, one insect that we can plan on being a consistent threat every year is thrips. This pest will infest 100% of the cotton planted in Alabama every year. What we cannot always predict, however, is when thrips pressure will peak. In a “normal” year in Alabama, we expect thrips pressure to be worse on early planted cotton and to be less later in the planting window as weather conditions improve. In 2021, this was not the case. Spring rains kept weedy hosts viable for a longer period, resulting in thrips pressure being the greatest on cotton planted after the middle of May. Much of our cotton was planted in this window and nearly 75% of our acres required a foliar treatment to supplement at-plant insecticides.

We have several options for at-plant management of thrips including insecticide seed treatments, and in-furrow liquid or granular materials. There are pro’s and cons of each approach, so deciding which strategy to use may make sense for one situation and not for another.

At-Plant Insecticide Options

Insecticide seed treatments (ISTs) are currently the industry standard for thrips control, due primarily to the ease of application. However, under certain conditions control is variable. If conditions are not conducive to seedling growth, particularly if nighttime temperatures are cool, seed treatments alone may not provide adequate control. Due to developing resistance, particularly to thiamethoxam, we recommend seed be treated with an imidacloprid based seed treatment. There are several brand names, and some include additional insecticides, but imidacloprid should be a component. Under light to moderate thrips pressure, ISTs may provide adequate control. Seed could also be treated with acephate (e.g., Orthene) or acephate could be added to imidacloprid, however in most cases a bag of over-treated cottonseed cannot be returned if not planted.

Liquid or granular in-furrow insecticide applications are another at-plant option to manage thrips. These can be used to replace or supplement an IST. In many cases, in-furrow applications provide better control of thrips, however using them requires extra equipment, proper calibration and time when planting. Imidacloprid at the highest labeled rate has consistently provided good results in our trials across Alabama in recent years. Acephate has provided more sporadic control, likely due to the wet springs we have faced over the past 2 years and leaching out the chemical before the roots can uptake the needed amount to provide control. Aldicarb, now available as AgLogic15G, is another in-furrow option. This granular product provides excellent control of thrips and provides control of nematodes as well. Keep in mind that aldicarb is a restricted use pesticide and additional training may be required to use this product.

Foliar Insecticides

Foliar insecticides may be needed to supplement at-plant treatments. However, foliar applications should never replace an at-plant insecticide. Thrips can injure seedling cotton until around the 5^th true leaf stage. Research shows that foliar applications are usually most effective when made at the 1^st true leaf stage. The Thrips Infestation Predictor for Cotton is a reliable tool that predicts the relative risk of thrips injury for cotton planted at a given location and planting date. To maximize the accuracy of the model, it should be run for several days before and after planting, as unpredicted weather patterns may alter the prediction. This tool should not be used to determine planting dates, but rather to help plan out fields or planting dates for cotton that will likely need a supplemental foliar application. Several options are available to use to supplement at-plant insecticides.

·         Acephate (3 oz/A) is an effective and relatively inexpensive option, however it has the potential to flare secondary pests such as spider mites and is the least rainfast of the available recommended options.

·         Bidrin (3.2 oz/A) is another option that is effective and less likely to flare spider mites and is more rainfast than acephate, however it is more likely to cause crop injury when tank-mixed with herbicides.

·         Dimethoate (6.4 oz/A) is another cost effective and efficacious product with good rainfastness, however it is the most likely to cause crop injury when tank-mixed with herbicides.

·         Intrepid Edge (3 oz/A) is another effective option. Intrepid Edge is less likely to flare secondary pests but may need the addition of a surfactant to help with efficacy.

·         Pyrethroids are not effective and should not be used to manage thrips.

Effective thrips control is critical to get the 2022 crop off to a good start. When considering areas to cutback on costs, do not skip out on at-plant (IST or in-furrow) insecticides. We cannot manage thrips without having protection for the seedlings as soon as they emerge. If planting into cool, wet conditions, be prepared to make supplemental foliar sprays to help seed treatments get seedlings to the 5^th true leaf stage. More information about thrips can be found in Pests of Alabama Cotton: Thrips (ANR-2718). For more information on thresholds and insecticide recommendations, visit the Alabama Cotton IPM Guide (IPM-0415). To stay up-to-date on the Alabama cotton insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter and Podcast, and the Syngenta Pest Patrol Hotline.

What Did We Learn about Cotton Insect Management in 2021?

Several cotton insects presented unique or unusual infestation patterns in 2021. The following is a discussion of insects as they occurred during the season and what we may want to consider as we enter the 2022 crop year.

Cotton seedlings showing varying thrips injury in 2021.

Thrips, for the second season in a row, reached their peak injury period in late May to early June. Therefore, the heaviest damage was to cotton planted after about May 10-15. Growers should be alert and protect all seedlings from thrips injury until plants reach about the 5th true leaf. This can be done by applying a timely foliar spray when seedlings are at the 1st true leaf. The Thrips Predictor Model, developed by NC State with research data from all Southeastern states, is very useful in alerting to potential injury in this late planting window, especially when it is run weekly until all seedlings are safe from injury. This phenomenon of thrips damage on late planted cotton is likely driven by frequent rainfall in the early to mid-planting window. Excessive rainfall tends to sustain and keep lush wild host plants that harbor thrips, thus delaying their movement to cotton.

Plant bug infesting 7 node cotton in Belle Mina, AL in 2021

A second pest that presented an unusual infestation pattern last year was tarnished plant bug. A heavy, statewide movement of adult plant bugs from wild hosts to cotton occurred between June 13-15. Reports and observations about plant bug migration came from Central Alabama, Tennessee Valley, Gulf Coast and Wiregrass during this 72-hour period. This movement, had it been from one specific area, would have been expected, but the fact that it occurred statewide within a short time had never before been observed or reported. All available media, social, electronic and telephone hotline, were employed to alert agents, field advisors and farmers. These early season adult plant bugs immediately began feeding in young squaring cotton, causing pinhead square loss in the early fruiting window. At the same time, female adults were depositing eggs into the tender stems of cotton, producing a hatch of immature plant bugs 3 weeks later in cotton between weeks 1 and 3 of bloom. Where timely controls were not made, “dirty” blooms resulted, and yields were reduced.

Stink bugs can cause damage until bolls are ~25 days old.

One other insect, stink bugs, should be part of this discussion. Stink bugs were more numerous than expected last season following what we thought was a colder than normal winter, including a particularly cold week that occurred in mid-February. We realize that though stink bugs have been our number one most damaging insect in cotton for the past 25 years, we are still refining or fine tuning our control strategies. One observation made in 2021 was that mid to full season varieties may require an additional late season application as compared to early maturing varieties. Basically, stink bug controls are warranted until the uppermost bolls – top bolls that are expected to be harvested – are about 25 days old and hard to the touch. During boll fill, a stink bug application should give about 2 weeks control or suppression except in field borders adjacent to corn, peanuts, pecans or other alternate stink bug hosts. After stink bugs enter cotton, beginning about the 3^rd week of bloom, any applications targeting plant bugs should include an insecticide or tank mixture that controls both pests.

Take Home Point:

The take home message from these occurrences is that growers and other ag advisors must be aware of more than just what they see in local fields. They must be “in the loop” from a bigger perspective in order to be alerted to unusual insect outbreaks. The Alabama Extension Cotton Entomology team has lots of eyes and ears throughout the state and receive daily and weekly feedback that can be passed along to all involved.

Ways to stay in the loop:

Syngenta Pest Patrol Hotline

Alabama Crops Report Newsletter and Podcast

Alabama Cotton Shorts Newsletter

AgFax Seasonal Crop Reports (Subscribe to Southeast Cotton)

Summary of the 2021 Alabama Cotton Insect Situation

 They always say, “there are no two growing seasons alike,” and 2021 was no exception. Spring rains across much of Alabama pushed back planting, causing a lot of “late” cotton. Several storms also moved through later in the year causing headaches across different regions of Alabama. Even with all the issues we have had, we still have good yield prospects this year. Hopefully we will have a cooperative finish to the harvest season and be able to get everything out in a timely and efficient manner.

Like last year, insects were not a major limiting factor. This is largely due to good scouting and timely insecticide applications when needed. Starting at burndown and going through to the end of bloom, several insects required monitoring and treatment. Walking back through the season, here is a look at what was observed and experienced.

Grasshoppers caused concern on a large percentage (≈60%) of acres statewide, primarily across central and south Alabama, and particularly on our sandier soils. Most of these fields were in reduced or no-till systems and required an insecticide at burndown or at-planting to mitigate risk of stand loss from this pest. In general, grasshoppers were managed effectively and little or no loss is expected from them. In a “normal” year, we would have expected thrips pressure to be relatively light due to the high percentage of cotton planted late. However, as experienced last year, late planted cotton experienced significant thrips pressure. The majority of the acres needed a foliar insecticide to supplement seed treatments, and most of those acres received one. The emerging mollusk pests (slugs and snails) also caused issues. Slugs are always a concern in cool, wet years and in high residue fields. Snails were a particular problem in several fields in Southeast Alabama. We currently have limited options for slugs and no options for snails (outside of tillage). These pests caused some replanting in spots this year.

The tarnished plant bug was the pest that caused the most headaches for pest management decision makers in 2021. Within a 4-5 day stretch in mid-June, a major plant bug migration occurred statewide. This is was a rare event, as normally plant bugs move from spring hosts to cotton at different times in the north and south. This mass migration was further complicated by the overall lateness of the crop. Adult plant bugs primarily infested the earliest planted (most mature) fields that were just beginning to develop pinhead squares (a small proportion of the overall crop). Plant bugs began feeding on these pinhead squares and laying eggs that developed into an embedded population of immatures in July. With much higher than “normal” populations in fields statewide, the plant bug issues never played out as we are used to.

In addition to tarnished plant bugs, the clouded plant bug was also found in many fields across central and south Alabama. While not at treatable levels alone, this pest drove insecticide selection decisions in several fields. Many fields at peak bloom, requiring sprays for stink bugs, still required scouting and treatment for plant bugs. Overall, stink bugs were at high numbers statewide, including the Tennessee Valley, where stink bugs are historically considered a sporadic pest. Many fields across Alabama required 4 or more sprays for the bug complex this year. In many cases, proximity to corn appeared to play a key role in the overall pressure of the bug complex in cotton.

Other secondary pests, such as spider mites and aphids were in fields and required attention at times, but overall were light statewide this year. Similarly, Alabama cotton experienced a light bollworm year. Although some of our traps caught high numbers of moths at the peak flight, we did not receive reports or observe escaped bollworms or significant damage from worms. As has been observed for several years, the 2- and 3-gene Bt varieties provide very good control of bollworms in Alabama.

As we prepare to move into the 2022 planning season, it is important to think back through what happened in 2021 and try tweak our pest management plans to continue to effectively manage and keep losses to insect pests low.