Points to Consider with Alabama Cotton Insect Management in 2023

1.       Grasshoppers. Grasshoppers tend to be worse in lighter, well drained soils and following dry winters in reduced tillage fields. Immatures begin hatching out in late March and continue until June. Stand loss occurs when grasshoppers feed on the mainstem of emerging seedlings. Preventative insecticide applications are a judgement call based on the risk a grower is willing to take.

2.       Thrips. Getting cotton seedlings off to a good start is important for maximizing yields. Remember that what we see above ground is a good indication of the below ground root system. Use the Thrips Infestation Predictor Model (link) to help gauge which planting dates are at the highest risk of infestation.

3.       Tarnished Plant Bugs. Migrating adults in June may or may not reduce pinhead square retention below 80-85%. However, they are depositing 100-150 eggs per female that will hatch out in July to present post bloom control needs. Don’t give them a head start. When treating plant bugs after the 2^nd to 3^rd week of bloom, use tank-mixtures or chemistry that will also control stink bugs.

4.       Aphids. Aphids always crash from natural disease, sometimes a little later than desired. If controls are warranted, use a chemistry that will also suppress plant bugs.

5.       Bollworms. Damaging levels of bollworms have not been an issue since 2017 but still keep an eye out between July 20th and August 10^th if planting 2-gene cotton. Bollworm control with foliar insecticides is better when applied to small worms.

6.       Spider Mites. Mites are present in most fields season long. They reproduce and spread faster during hot, dry periods. Do not make treatments when rainfall is abundant or in the forecast for the next few days.

7.       Stink Bugs. Stink bugs are often the most damaging pest of Alabama cotton. One reason is time, stink bugs damage bolls in the mid-to-late season, leaving little time for the plant to compensate. The most critical period for stink bug control is between the 3^rd and 6^th weeks of bloom when most of our yield is being set.

8.       Be Informed. Cotton insect management is different from all other aspects of row crop production. The situation changes from week to week and sometimes field to field. To stay up to date on the situation in Alabama, subscribe to the Pest Patrol Hotline (link), Alabama Insects Blog (link), Alabama Crops Report (link) and Cotton Shorts (link) Newsletters, and the Alabama Crops Insect Report (link).

Summary of the 2022 Alabama Cotton Insect Situation

We certainly had some challenging situations through the cotton production season in Alabama in 2022. From severe drought in some areas, to excessive rainfall in others weather played a major role in the in-season management of the crop. Even so, we expect to have a very good cotton crop in 2022. We have heard several reports of 3 or more bales per acre being picked and expect our state average to be around 900 lbs. According to data from the USDA, Alabama planted just over 425,000 acres of cotton this year.

Overall, insects were not a major yield limiting factor for Alabama cotton in 2022. Many fields required multiple applications, as the statewide average was ≈5 applications per acre. However, thanks to proper scouting and the use of thresholds, the overall reduction of production caused by insects is estimated to only be 2.94%.

To start the season, grasshoppers required attention on many fields across Alabama, particularly on sandier, well drained soils and those under reduced or no-till strategies. No losses are expected from grasshopper feeding as insecticides applied at-burndown or at-planting are generally effective in controlling populations and preventing economic losses. For two seasons in a row, thrips pressure was higher in later planted cotton. Most of our cotton acres received foliar treatments to supplement at-plant insecticides (seed treatments or in-furrows). In many cases, the biggest concern around making foliar thrips sprays was the risk of flaring spider mites. In dry pockets, many farmers elected to use materials that are less harsh on beneficial insects, even at a slightly higher price point. Other pests such as slugs, snails or cutworms were observed and reported in a few fields, but rarely at economic levels during the early season.

Adult Tobacco Thrips

Spider Mite Injury

As the cotton crop began squaring in June, many fields across the state started dealing with two-spotted spider mites. In many cases, spider mites were worse in fields that received a thrips spray with a disruptive chemical, but that was not always the case. As we have shifted to reduced/no-till systems and started adopting more cover crops, early season spider mites have become a more consistent issue. This shift in combination with hot, dry weather can quickly cause a spider mite outbreak, even if everything has been done “right” in the field all season long. While losses to spider mites were low, some fields required multiple applications to keep populations from causing economic damage.

Another pest that farmers had to deal with during this time was the tarnished plant bug. Adult plant bugs infest cotton in June, at the on-set of pinhead squares. In general, plant bug pressure was lower in 2022 than in 2021. Many reports during the squaring season were that adult populations only required one application to maintain adequate square retention. In general, adult plant bug pressure was higher in earlier planted cotton, as these fields were the most attractive as adults were migrating from weedy hosts.

As cotton matured into the blooming window in July and August, the bug complex required most of the insect attention. Immature plant bugs, deposited as eggs by migrating adults in June, begin appearing around first bloom each year. In some areas of Alabama, this population was difficult to control, mostly due to issues complicated by weather. Insecticide wash-off was a major concern in areas of SW Alabama where rainfall was abundant. In addition to wash-off, many farmers were unable to apply plant growth regulators in a timely manner because fields were too wet to get sprayers in. This resulted in rank cotton, which is attractive to plant bugs and, in many cases, getting the insecticide to the plant bugs was difficult. Immature plant bugs prefer to feed on larger squares. When these squares are hidden down in the canopy, getting insecticide coverage is difficult, regardless of the choice of chemical, adequate control is rarely achieved in just one application. In these situations, and in other many areas of Alabama, plant bugs required multiple applications during the blooming window for control.

Immature Tarnished Plant Bug

Adult Green Stink Bug

The other player in the bug complex, stink bugs, are annually the most yield limiting insect pest in Alabama. This season, plant bugs were not as prevalent as normal. Based on observations in corn, we expected a much higher than usual stink bug season in cotton, as nearly all stink bugs that infest cotton turn over a generation in corn first. As corn began to silk, large populations of adult stink bugs were mating, and high numbers of egg masses were observed. However, the hot, dry conditions in June that hurt corn also appeared to harm stink bugs. The subsequent population that moved from corn to cotton was not as large as anticipated and many fields only required one application to manage this pest.

Other pests, such as aphids, silverleaf whiteflies and clouded plant bugs were observed in fields at low levels, but none were reported to reach treatment or economic levels. In general, the bollworm flight was relatively light, and our 2- and 3-gene cotton varieties provided very good control of bollworms and other caterpillar pests.

In summary, the Alabama Cotton Insect Situation was highly variable in the 60 counties cotton was produced in across the state in 2022. The situation changes from week to week and field to field, making scouting and monitoring critical for maximizing profitability. As we head into the winter, we will continue to evaluate insect management strategies to determine how we can tweak our system to effectively manage and keep losses to insects low.

Alabama Insect Situation: September 8, 2022

As the calendar turns to September, most of our cotton is past insects, some is beginning to receive defoliation applications, and all is hoping for a dry fall so we can get all the lint from the field to the basket. With the cotton season mostly behind us, the soybean insect situation is beginning to build.

VBC collected in 5 sweeps near Prattville, AL.

Over the past week, we have gotten several reports and phone calls about defoliating caterpillars in soybeans across central and northeast Alabama. While a complex of worms is in fields, soybean loopers (SBL) and velvetbean caterpillars (VBC) are the dominate and most important species in the mix. In addition to a detection technique (i.e., sweep-net or drop cloth), looking at the defoliation within the plant canopy can give an idea as to which species is doing most of the damage.

VBC: 4 pair of prolegs, defoliation begins in the upper portion of the canopy

SBL: 2 pair of prolegs, defoliation begins in the lower portion of the canopy

We have a couple of thresholds to use based on scouting technique for defoliating caterpillars. Prevent 20% defoliation during peak podfill (R1-R6), from R6 to R6.5 (≈7-10 days), prevent 30% defoliation. Alternatively, treat when 38 VBC or 19 SBL are found per 25 sweeps. As mentioned above, most fields will have a complex of worms, not just one or the other. Thus, detection techniques may be more useful for determining pest complex than treatment levels. Species composition is important for insecticide decisions. Another important reason for detection techniques is to get an idea of the size of the worms in the field. Like most things, VBCs and SBLs consume more food as they grow. In other words, larger worms eat more leaves (in a shorter amount of time) than smaller worms. If the majority of the population is made up of worms nearly an inch long or bigger, then action should be taken immediately. If most of the worms are small (less than 0.25 inch), then there is more time to make a spray.

Once the decision is made to treat, what are our options? There are several good materials to choose from, considerations for what to choose involve pest complex, economics and weather.

If soybean looper is the dominate pest, pyrethroids will do more harm than good. Our options for soybean loopers include diamides (e.g. Besiege, Vantacor, Elevest) or Intrepid/Intrepid Edge. These products provide good initial and residual control of the spectrum of the defoliating caterpillar complex. While the mentioned options provide excellent control of VBC, most labeled pyrethroids and IGRs also provide control. One issue with pyrethroids is the lack of residual control. We have seen instances in the past where multiple applications were required to manage VBC populations because of an extended migration over several weeks that would have likely been alleviated by a single initial application of a diamide.

If you would like to provide reports or observations on the insect situation from your region, please let us know. You can reach Scott Graham at 662-809-3368 or scottg@auburn.edu or Ron Smith at 334-332-9501 or smithrh@auburn.edu.

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

Alabama Cotton Insect Situation: August 26, 2022

Sunshine. That’s what the Alabama cotton crop across much of central and south Alabama is missing as of today. The 10-day forecast shows 50% or greater chances of rain across much of the state. As a lot of cotton is starting to open, we need to get out of this pattern. We realize that while insects are still in many fields, they do not pose the greatest risk to our crop at this time.  We have started seeing and hearing about some boll rot and hardlock going on in central Alabama and have seen a little bit of germination as well. Hopefully we get some sunshine and hot weather to dry all this cotton out and save as much of the lower bolls as we can.

With that in mind, we still have some fields with a ways to go and that need to be protected from insects. We are getting more calls on plant bugs than we are stink bugs right now, which is pretty unusual. Some things thoughts about insect management we enter the final push of the season.

Last effective bloom date: This is simply the day when you drop below at least a 50% chance for a white bloom to make it to the picker basket. Alabama is far too diverse to give a general LEBD, but most folks know how far out they can push a bloom and reasonably expect it to make it to the basket in their area.

With a given LEBD in mind, here are some key things to remember for insect controls:

Plant bugs can damage bolls until they are about 10-12 days old

Stink bugs can damage bolls until they are about 25 days old

Spider mites can cause reduced yields until harvestable bolls are     finished filling

Knowing we have stink bugs and plant bugs in some of these fields that need to be cleaned up, what are we going to do? Depending on your local weather pattern, I would avoid acephate at this point. While it is a very good bug material, it also has high wash off potential. We need a minimum of 8 hours with no rain, but really would prefer 12 or more. We are still hearing in some places that Bidrin is getting harder to find, hopefully we can still have that option. That leaves pyrethroids, primarily bifenthrin. We have heard reports of the past week about issues controlling plant bugs in south Alabama with pyrethroids. We could chase a lot of the issues back to several weeks prior when generics were used. In general, bifenthrin is the best “bug” pyrethroid we have. While the others are good on some other pests, we really would like bifenthrin better, particularly on plant bugs.

Another thought on late season insect management. Let’s try to get our “clean up” spray on before the cotton starts to fall over and cross rows with each other. While the sprayer tracks wont runover that much cotton, we would rather not runover any at all.

If you would like to provide reports or observations on the insect situation from your region, please let us know. You can reach Scott Graham at 662-809-3368 or scottg@auburn.edu or Ron Smith at 334-332-9501 or smithrh@auburn.edu.

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

Alabama Cotton Insect Situation: August 18, 2022

We are beginning to see some open bolls across south and central Alabama, the end is in sight. Not much has changed over the past week with our cotton insect situation. We are still fighting the bug complex in many fields across Alabama. In addition to tarnished plant bugs and stink bugs, we are also starting to observe some clouded plant bugs and leaf-footed bugs as well.

Cotton

SLWF

We are still in the early stages of the silverleaf whitefly (SLWF) situation in our areas with historic outbreaks (some parts of the Wiregrass). It is still not time to panic, but there are some fields infested that need to be watched.

Fields to be alert of include any of or a combination of the following:

• Late planted
• Drought stressed (hot, dry weather and/or dryland)
• Low beneficial insect populations (fields with recent insecticide applications)
• Hairy leaf varieties

Below is a copy of the SLWF handout from our colleagues who have a lot of experience fighting these critters at UGA.

SLWF Handout - Click to Enlarge

Bug Complex

Adult leaf-footed bug

While the presence of clouded plant bugs doesn’t necessarily change our insecticide recommendations, the presence of leaf-footed bugs would. In general, pyrethroids do not provide as good of control of leaf-footed bugs as the organophosphates do. That leaves us with 6 oz of Bidrin or 0.75 lbs of acephate. Due to the silverleaf whitefly (SLWF) situation in the historic SLWF areas (some parts of the Wiregrass), I would avoid Bidrin at this point and go with acephate. While we still don’t fully understand the reason, Bidrin really seems to exacerbate a SLWF infestation. In areas outside of this localized situation, Bidrin and acephate are both in play, depending on the availability of each.

Many of the people we have talked to have said they are getting ready to put out their “clean up shot” and walk away. Another season is beginning to wind down, but we need to keep scouting our later planted cotton and be prepared to protect bolls as needed.

Soybeans

Defoliating caterpillars (soybean loopers and velvetbean caterpillars) continue to build and require treatments in fields across central and south Alabama. We are watching traps closely in north Alabama to monitor when populations should be expected there as well. In addition to caterpillars, we are still fighting stink bugs, both the traditional species and the redbanded in many fields. Proper ID is critical or all of these species as concoctions to kill different species complexes may vary greatly.

Take Home Messages

While a fair amount of our cotton is out of the woods, we need to keep scouting in later fields and be prepared to take action when necessary. Be on the lookout for SLWF in areas with past experiences. Scout and properly ID which insects are in soybeans to make the most economic control options possible.

If you would like to provide reports or observations on the insect situation from your region, please let us know. You can reach Scott Graham at 662-809-3368 or scottg@auburn.edu or Ron Smith at 334-332-9501 or smithrh@auburn.edu.

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

Alabama Insect Situation: August 12, 2022

 Cotton

Not much has changed over the past week with the cotton situation. We are still fighting bugs in some fields statewide, while other fields are relatively clean. A little cotton is starting to open, while most of it isn’t quite out of the woods yet. We have talked to several folks that are starting to put out a “clean up” shot then walking away. Keep in mind that our stink bug threshold bumps up to 30-50% internal boll damage during the 7^th and 8^th weeks of bloom. This is because there aren’t as many susceptible bolls left in the field. They key thing to remember with stink bug management is that they can damage a boll until it is about 25 days old. So, we need to protect bolls we plan to harvest until the are at that point.

We continue to hear that the spider mite situation in the Wiregrass just won’t go away. Research from the mid-south says you can stop spraying spider mites at NSWF 5 + 350 heat units (likely somewhere around NWAF 2 or 3). Based on my experiences in the mid-south, and my short time working with cotton insects in Alabama, I think we need fight a little longer than “cutout” in the Wiregrass. In areas where the top crop plays a significant role in the yield potential of the crop, we need to protect from spider mites until we feel those bolls are filled. Spider mites damage cotton by sucking nutrients out of the leaves and can cause premature defoliation. In these situations, if we don’t get all the necessary photosynthate from the leaf to the boll, we will see yield losses. While it sounds like some control options are getting harder to locate, we do have several options (abamectin, Zeal, Portal or Oberon).

We are hearing reports of high flushes of bollworm moths in some fields across the state. We have also heard about some 2–3-day old worms found under bloom tags. To date, we have not heard of any issues with escaped worms in our 2-gene cotton (outside of 2017) or in our 3-gene cotton (at all). We also plant Bt sentinel plots across the state and se have not observed any issues with control in those plots either. We do not recommend treating bollworms based on eggs for this reason. We are paying a premium for these technologies so let’s give them a chance to work.

One final note on cotton, the silverleaf whitefly situation in Georgia is beginning to move west. We are hearing about fields being treated near the Alabama line and have received a report of SLWF in at least one field in Alabama. This will not be a widespread issue across the state but can have major impacts on cotton in the historic SLWF area. We will go into full details on SLWF as the situation evolves, but just to give a brief refresher:

·      Late planted cotton is at a greater risk

·      Threshold: 50% of leaves (5^th node from terminal) are infested with 5+ immatures per lea

        Immature SLWF resemble aphids, however if you rub the bottom of the leaf on your shirt SLWF will stay on the leaf and aphids will rub off

·         Insect growth regulators (Knack and Courier) are the backbone of SLWF management, but they must be applied timely (i.e. early)

Soybean

We are beginning to pick up looper and velvetbean caterpillar populations in fields. In some cases, defoliation is reaching 15-20% and treatments are going out. Scout to make sure you know which species are in the mix to make the proper insecticide selection. We have received reports of velvetbean caterpillars in fields in the TN Valley as well. We don't often get VBC that far north. We had several fields sprayed in 2020 but it had been quite a while prior to that. VBC are easily managed with most labeled insecticides, but they have every bit the damage potential as soybean looper and should be given the same attention.

The redbanded stink bug situation is still building as well. Once the immatures start to develop in fields, they can be difficult to get back under control. Two-way tank-mixtures of pyrethroids, acephate and/or neonics are necessary. If we come out swinging early, we can manage them. Things get difficult when populations build and are left unchecked too long.

Deer Survey

In response to a farmer request, the Alabama Extension Agronomics Crops Team is conducting a survey to better understand the impacts of deer population on crop production. Please take a few moments to help us collect information to try to use to figure out ways to mitigate deer losses in your row crops.

You can take the anonymous survey here (link).

If you would like to provide reports or observations on the insect situation from your region, please let us know. You can reach Scott Graham at 662-809-3368 or scottg@auburn.edu or Ron Smith at 334-332-9501 or smithrh@auburn.edu.

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

Alabama Insect Situation: August 5, 2022

The crop situation is all over the board in Alabama. Fields in the Gulf Coast region have received rains in something like 30 of the last 37 days, while fields in North and Southeast Alabama are rated as abnormally dry and in some cases, in a moderate drought (link). Thus far, cotton in Central and East Central Alabama looks really good. Retention has been high and after a slow start, rains have picked up and the crop is rolling.

Cotton

Dirty bloom with TPB nymph

As we have been discussing on the blog, the bug complex is what we need to be scouting for from this point forward. We have observed and have received reports that plant bugs are a little bigger player in the complex at this point in the year than we normally expect. We went to a cotton and corn field day at the research station at Fairhope yesterday (8/4) and plant bugs were the big topic. Scouts and consultants reported heavy numbers of plant bugs and dirty blooms in fields, particularly those around corn. Plant bugs have likely already moved out of corn, but heavy egg lay when they moved, combined with rains making getting into the field difficult and we have a situation where an imbedded population of plant bugs takes hold. We have seen similar situations in the TN Valley, although reports are that some fields are in good shape following applications over the past 10-14 days.

Overall, reports are coming in that the bug pressure is field to field in some areas. In other words, some fields have high pressure and other fields we aren’t seeing much. This drives home the importance of having someone looking and scouting to ensure we have economic infestations prior to making applications.

The spider mite situation in the Wiregrass seems to be continuing. Lack of rain and hot weather is exacerbating things. In these situations, we need to make sure we are scouting for other pests and only treating when needed, as automatic sprays may unnecessarily flare mites. If mites are in the field and stink bugs or plant bugs require attention, don’t hesitate to spray…but consider tank-mixing a miticide to help keep mites in check.

Soybeans

Our soybean looper traps in Central Alabama (near Tallassee) picked up this week. We collected nearly 500 moths over a 7-day period. It is time to start looking and thinking about SBL in Central and South AL. Keep in mind our thresholds are 19 SBL per 25 sweeps -OR- to avoid 20% defoliation until R6.5. We are also seeing a mix of green cloverworms (GCW) and velvetbean caterpillars (VBC) in the mix as well. In fact, as we were typing this blog (8/5), we received a report of economic infestations of VBC and defoliation in late planted beans in SW Alabama. Identification is critical, because GCW and VBC are easily controlled with pyrethroids or IGRs (Dimilin, Diamond), while SBL require a shift to the “newer” insecticides (Prevathon/Vantacor, Besiege, Elevest, Intrepid Edge, Blackhawk) due to resistance.

As our soybean crop continues to develop and fill pods, stink bugs are infesting fields. We are still getting calls about redbanded stink bugs, particularly in the Black Belt. Thus far, they have not made it to the TN Valley, and it is probably unlikely that they will…BUT never say never. In North Alabama, we need to be scouting for the traditional stink bug complex. Our threshold is 4 stink bugs per 25 sweeps. This is aggressive, but in a validation study we did last year, this threshold made us more money than a more relaxed threshold of 6 or 9 per 25 sweeps.

Deer Survey

In response to a farmer request, the Alabama Extension Agronomics Crops Team is conducting a survey to better understand the impacts of deer population on crop production. Please take a few moments to help us collect information to try to use to figure out ways to mitigate deer losses in your row crops.

You can take the anonymous survey here (link).

Take Home Points

Keep scouting fields, the situation is dynamic in Alabama’s cotton and soybean fields. “Boots on the ground” help us to get the highest return on investment for insecticide application decisions. Be prepared to treat when needed, but only when needed.

If you would like to provide reports or observations on the insect situation from your region, please let us know. You can reach Scott Graham at 662-809-3368 or scottg@auburn.edu or Ron Smith at 334-332-9501 or smithrh@auburn.edu.

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