Tales of Cotton Insects: May 20, 2024

We have received several calls about thrips over the past 5-7 days. Right now, cotton planted in May is at the highest risk of thrips injury and cotton planted through about the 20^th is at very high risk across most of the state. This has changed over the past week with all the rains we have received. One thing to consider is that a heavy rainstorm can alleviate some thrips pressure. However, they may not always do enough. On Saturday (May 18), we received a report from Cherokee county of multiple fields with anywhere from 2 – 6 thrips per plant on 1-2 leaf cotton (threshold is 1-2 with immatures present). Other reports are that cotton treated with AgLogic looks good and cotton with a seed treatment or imidacloprid in-furrow needs a spray. 

Note: All reports are that ThryvOn cotton looks as expected and is not taking on injury justifying a foliar spray.

The question is, what to spray. There are a couple of options for foliar treatments for thrips:

Acephate 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. (With the recent weather we have had, I am not concerned about flaring spider mites)

Bidrin 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.

Intrepid Edge 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.

Below is a chart with thrips counts and injury ratings from an on-farm trial we did in 2020 in Madison County (AL).

On-farm thrips trial in 2020. Cotton was treated with Gaucho (insecticide seed treatment). Foliar application was made at the 1 true leaf stage. Ratings were made 7 days after application. An injury rating (yellow line) of "3" indicates unacceptable injury. 

We are still receiving reports of grasshoppers threatening stands in central Alabama and the Wiregrass region. In some areas, we have a good stand but rain is keeping us out of the field for a few days. In others, the question has just been should we pull the trigger or not. In fields with historic issues of stand loss from grasshoppers and high numbers in the field, treatment should be considered. We don’t want to get into replant situations, especially in areas where we lost a few days in the field and are trying to get caught up. Acephate (2/3 lb) is needed to kill adults and in some fields nymphs are still hatching and Dimilin can provide residual suppression. Cotton is most susceptible in the "crook" stage, but grasshoppers can still threaten stands once it has fully emerged.

If we can be of any help, please don’t hesitate to reach out and let us know (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). To stay up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.

Tales of Cotton Insects: May 3, 2024

The Alabama cotton insect situation has started to pick up over the last few days. We have received several reports of grasshoppers in fields across central Alabama. Our observations and reports are that grasshoppers have reached the adult stage in some of the fields, which is a little earlier than normal, but the winter was also somewhat mild. This is important to note, because adult grasshoppers are harder to kill and are not affected by the growth regulator Dimilin. The presence of wings is the only way to identify adult grasshoppers as the immature stages do not have them. We do not have a threshold for grasshoppers. With that in mind, treatment decisions are made based on the level of risk a grower is willing to take in a given field (how many grasshoppers are out there?). In some fields, grasshoppers do not eat cotton while in others they may destroy dozens of acres. Field history can provide some indication of what may happen this year. If grasshoppers have eaten cotton in a field previously, they seem to be more likely to do so again.

Treatment Decisions

At this point, I would probably assume adults are present in fields. That means acephate (0.67 lbs ai/A) is the go-to product. I would also tank-mix Dimilin (2-3 oz/A) to provide residual control of nymphs still emerging. Pyrethroids have provided poor to sporadic control of adult grasshoppers in previous years.

If we can be of any help, please don’t hesitate to reach out and let us know (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). To stay up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.

Adult differential grasshoppers

Cotton seedlings damaged by grasshoppers

Alabama Thrips Risk: April 18, 2024

The Thrips Infestation Predictor Model for Cotton (link) is a useful tool to use to help understand which planting dates or planting windows are at the highest risk of thrips injury. This model predicts how thrips movement and cotton growth will line up based on recent and predicted weather patterns. The model also provides some context with the last 5 years for thrips pressure at your given planting date. We started running the model to get an idea of what thrips pressure is predicted as we move into the early planting window.

South Alabama

We ran the model in Henry and Escambia counties and cotton planted until about the first week of May is at the highest risk of thrips injury.

Central Alabama

The model showed in Autauga, Lee, Talladega and Fayette counties that cotton planted after about May 10^th is at the highest risk of thrips injury.

North Alabama

North Alabama (Cherokee and Limestone counties) were similar to central Alabama with cotton planted after about May 10^th being at the highest risk of thrips injury.

To look at the models we ran, you can click here.

Keep in mind that the model is fluid and things can change based on an unexpected rain event (or a missed expected rain). You should update the model every couple days before and after planting to make sure you are seeing the most accurate version. Remember that the model is used to understand risk of thrips injury and which fields may need a supplemental foliar application.

If we can be of any help, please don’t hesitate to reach out and let us know (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). To stay up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.

Preparing for the 2024 Cotton Season

The latest USDA estimate has cotton up significantly (430,000 acres) compared to last year. Hopefully, this means we will be able to spread insect pressure across more acres and dilute some of the populations. We cannot rely on this, however, and farmers should be prepared (budgeted) to make multiple applications for insects in 2024.

Some thoughts and considerations for this season in Alabama.

1.    Scouting and Monitoring. To most economically manage insects, fields should be scouted weekly to know what insects are in the field, and at what levels they are present. The situation changes week to week and timely applications can only be made if damaging levels are found in time to react.

2.   Spread the Risk. Consider planting the crop across a range of planting dates if possible. This can protect some of the crop from being vulnerable to variable weather patterns during the season. The current predicted weather for this season looks favorable for an early crop, so don’t be scared to jump out and get started as soil temperatures allow in the coming weeks.

3.   Pre-Plant Insects. To best reduce risk to “stand robbers” like cutworms, slugs and other pests, good winter cover burndown is essential. Ideally, covers would be terminated (dead) at least 3 weeks before planting. To quote my advisor at UT, Dr. Scott Stewart, “If it ain’t brown, don’t put seed in the ground.” If termination is closer to planting, consider adding a pyrethroid ±7 days of planting to reduce risk.

4.   Thrips. Use the Thrips Infestation Model (link) to prepare which fields may need a supplemental foliar application. Planting dates with a dark red or number close to “1” will likely benefit from an application, particularly if just a standard seed treatment is used. Note: ThryvOn cotton will likely NOT benefit from a foliar spray, regardless of planting date.

5.   Plant Bugs. Adult plant bugs will likely infest our earliest planted cotton first. These fields have the most food sources available when daisy fleabane begins to dry down. Our goal with adult plant bug management is to maintain at least 80% square retention and to reduce egg lay. Apply imidacloprid or Centric early season to accomplish this goal. As the crop begins to bloom, our attention turns to immature plant bugs that hatch out from the above-mentioned eggs. 

     Sometime around 1^st bloom, or 10-14 days after a June adult plant bug spray, is a good time for a tank-mixture of a knockdown insecticide and the insect growth regulator, Diamond. This material provides 2 to 3 weeks (6 -9oz rate) of residual “suppression” of nymphs and may be enough to get us to the stink bug window (around the 3^rd week of bloom). Using a black drop cloth in a couple areas of the field is the best way to scout for immature plant bugs and threshold is 3 nymphs per drop (=5 row feet).Note: ThryvOn cotton will likely NOT benefit from an application of Diamond.

6.   Stink Bugs. Beginning around the 3^rd week of bloom, every insecticide application should include a material that controls stink bugs (pyrethroid or organophosphate). Peak bloom (weeks 3-6) is the most important time to manage stink bugs. Instead of looking for stink bugs with a sweep-net or drop cloth, sample 10–12-day old bolls (≈1 in diameter) for internal signs of injury. Threshold is 10% damage during peak bloom. We should mention that this 10% does not represent every boll in the field, but 10% of the 10-12-day old bolls during that week of sampling.

     This year is the 100^th year of Extension Cotton Entomology at Auburn University and Alabama Extension. Our goal is the same today as it was in 1924: to help Alabama cotton farmers make the best insect management decisions possible. You can read a nice write up of the history of Extension Cotton Entomology in Alabama in Cotton Farming Magazine. 

      If we can be of any help, please don’t hesitate to reach out and let us know (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). To stay up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.

Alabama Insect Situation: Friday September 15, 2023

We have received multiple reports of redbanded stink bugs found nearing threshold levels in the Alabama Black Belt this week. Redbanded stink bugs (RBSB) are the most damaging pest of soybeans in Alabama. They are small, green and have a light red, orange or purple band across their shoulders (back). RBSB also have a small spine in between their legs that points back up towards their face. Populations tend to aggregate on early planted soybeans, then move to late planted beans as early planted beans are harvested. They can cause economic damage  until the R7 growth stage, unless there are adverse environmental conditions that promote poor seed quality (i.e., cool, wet).

RBSB are more difficult to control, particularly when the nymphs appear. If adults and nymphs are found (threshold=4/25 sweeps), then a full rate of bifenthrin + 0.5 lbs ai of acephate is needed for control. If sub-thresholds are found, then a full rate of bifenthrin plus a neonicotinoid (imidacloprid) may provide adequate control. If a threshold population of adults only are found, we recommend making an application of bifenthrin to knockback adults and try to stop egg lay.

Our soybean looper traps continue to be high across the state, but we have received few reports of damaging levels of worms in the field. Small loopers are highly sensitive to environmental conditions and are prone to "crash" if a cool snap hits. That is why most thresholds say to only count worms that are >1/4 or 1/2 inch. If threshold populations (19/25 sweeps, prevent 20%-30% defoliation) are found, then diamides (Vantacor, Besiege, Elevest) or Intrepid Edge is needed for control. Loopers are more difficult to control than velvetbean caterpillars or green cloverworms.

As always, if we can ever be of any help, or if you would like to provide input on the situation in your area, please don’t hesitate to reach out (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). To stay up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.

Alabama Insect Situation: August 31, 2023

Phone calls and reports have slowed considerably over the past 10-14 days. Most of the cotton is no longer susceptible to insects and some is beginning to open. We have some areas that have gotten good rainfall over the past week; however, many areas are very dry and need rain badly. Soybeans have been the focus of most calls this week, with stink bugs and caterpillars being the main concerns.

Soybeans

Stink Bugs

For the most part, early planted (April) beans are safe from most all of our insect pests, including stink bugs. Our threshold prior to R6 is 4 bugs per 25 sweeps. Once R6 (beans touching inside pods of upper 4 nodes) is reached, we double the threshold to 8 bugs per 25 sweeps for 7-10 days (R6.5-pod and pod wall beginning to turn mature color) then we can terminate insecticide applications.

We have observed green, southern green, brown and brown marmorated stink bug adults and nymphs in fields across the state. A high labeled rate of a pyrethroid will do a good job killing any of these in soybeans and save the crop from economic damage if threshold populations are found.

Caterpillars

Our soybean looper and corn earworm (podworm) trap counts have been up significantly the past couple of weeks. We have had more acres infested and treated for podworms this year than we have had in the past 5 or more years. Our threshold for podworms is around 6 per 25 sweeps.

Right now, the velvetbean caterpillar seems to be the dominant species in the mix thus far, which is good because they can easily be managed with most labeled insecticides. I would, however, be a little cautious with pyrethroids given their ability to flare loopers and the big moth flight we’ve experienced this past couple of weeks. The threshold for defoliators is to treat at 20% defoliation from R1-R6 and 30% defoliation after R6 for 7-10 days. Alternatively, treat when 38 VBC or 19 SBL are caught per 25 sweeps.

As always, if we can ever be of any help, or if you would like to provide input on the situation in your area, please don’t hesitate to reach out (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). To stay up-to-date on the Alabama insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.

Alabama Insect Situation: August 17, 2023

Plant bugs, stink bugs, bollworms, spider mites (cotton), velvetbean caterpillars, corn earworms soybean loopers (peanuts and soybeans) and stink bugs (soybeans) have been reported this week. In some places, cotton looks good and has good moisture, in others it’s scary dry and blooming out the top.

Bug Complex

Reports of green and southern green stink bugs have picked up this week statewide. After wondering if they would ever show up, they are here now. As we mentioned last week, our tests in south, central and north Alabama, are running 30-50% internal boll damage in untreated plots. We have started hearing reports from scouts and consultants that damage has jumped from less than 10% to 30% or more in the past week. While our older cotton is safe from bugs, later planted cotton (probably about mid-May on) is still at risk. The threshold is 10% damage weeks 3-6 of bloom and 30-50% in weeks 7-8.

Plant bugs are becoming a little spottier but are still heavy in some places. A lot of acres have received multiple applications of Diamond and that has helped keep populations manageable. Keep the fight up until cotton reaches NAWF 2, at that point, we should be free to cut it lose.

Spider Mites

We have received reports of spider mites across the state this week. In some cases, these are in fields that have been hammered for plant bugs, but not in every case. Historically, rain has helped reduce the impacts of mites, but that hasn’t seemed to hold true the last couple of years. We are not sure why this is, but it seems to be real. Look for signs of injury, then flip leaves over to confirm you have an active infestation. At this point in the season, we have a few options (abamectin, Zeal, Portal, Oberon), with abamectin being the most common used. There are varying levels of resistance, so if you have used some earlier this year, watch closely behind another application. Regardless of the product, we feel that higher rates give us better control later in the season as coverage is difficult with bigger plants and more canopy. One of the bigger questions we have gotten is when to cut lose spider mites. Research from the mid-south suggests mites can cause yield loss until about NAWF 2, so keep after them until at least that stage.

Soybeans

We have gotten several calls on defoliating caterpillars and stink bugs with some podworms mixed in. In some cases the soybeans are around the R5 stage and highly susceptible to all three, in others they are mid R3 and relatively safe from podworms and stink bugs. While pyrethroids provide good control of stink bugs, cloverworms and velvetbeans, they are an excellent way to create a soybean looper problem. Scout closely and make sure you don’t have loopers before spraying a pyrethroid. Our looper traps have picked up across the state this week and we expect to start finding worms really picking up over the next 7 to 10 days. Remember loopers have 2 pair of prolegs, VBC have 4 and GCW have 3. In fields with loopers, consider using a diamide insecticide like Besiege, Elevest or Vantacor, or a product like Intrepid Edge. If stink bugs are in the mix, I would consider adding the needed pyrethroid to make a full labeled rate for Besiege/Elevest, or adding a full labeled rate to Vantacor or Intrepid Edge.

Peanuts

Like with soybeans, defoliating caterpillars are starting to build in some areas. Peanuts are tough and can withstand quite a bit of defoliation. Be on the lookout but don’t treat if threshold isn’t met (4-8 per row foot). As dry as we are in some places, we do not want to make an unnecessary application an create a spider mite issue.

As always, if we can ever be of any help, or if you would like to provide input on the situation in your area, please don’t hesitate to reach out (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). 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 the Syngenta Pest Patrol Hotline.