Alabama Insect Blog

Thursday, June 13, 2024

Tales of Cotton Insects: Thursday June 13, 2024

Critical Window for Early Planted Cotton in Central and North Alabama

The plant bug situation has exploded over the week in Central and North Alabama. Based on reports and observations from about Montgomery north through the TN Valley and NE Alabama, all cotton planted on or before ≈May 10^th likely needs a plant bug spray. Overall, square retention is still high, but with some of the numbers reported, it will start dropping quickly if action is not taken (goal is to maintain 80%). Overall, pressure appears to be lighter in cotton planted on or after ≈May 15^th (much of that is just starting or not squaring yet). Note: Reports are that adult plant bug numbers are similar in ThryvOn and Non-ThryvOn cotton in most areas. This is not unexpected as most of ThryvOn’s impact is against immature plant bugs.

Multiple reports from Cherokee county are that the earliest planted fields are running anywhere from 20-35 adult plant bugs per 100 sweeps (threshold = 8). In these situations, imidacloprid alone may not be enough to preserve square retention. Adding mid-rates of acephate or a pyrethroid (depending on location) may improve control. Centric is another option for control.

In most situations populations are above threshold but in more manageable numbers. Our May 1^st planted cotton at Prattville averaged ≈12 adults per 100 sweeps this week and ≈9 per 100 sweeps at TN Valley. We have received some reports from the field of similar populations and that some fields are receiving a 2^nd adult application this week (following applications last week). High rates of imidacloprid alone, Centric (2 oz), acephate (0.5-0.67 oz) or pyrethroids (highest labeled rate, dependent on location) should suppress populations and preserve square retention. Keep in mind that no insecticide will provide more than 2-3 days of residual control for adults and square retention is the best way to determine efficacy, adult numbers can rebound from week to week as more move into fields.

Thus far, reports from south Alabama are that plant bugs are scattered here and there, but few fields are above threshold. These fields should be closely monitored as the migration will likely begin soon.

The next 10-14 days will be critical for plant bug management in central and north Alabama cotton. Timely applications of recommended insecticides will preserve square retention and reduce egg lay and nymphs hatching out in the coming weeks. Consider being prepared to make an application of Diamond with a knockdown insecticide ≈10-12 days following the adulticide applications going out now. One consideration for the “automatic” follow up may be weather. If fields do not receive rain in the next couple weeks, that may impact immature plant bug populations in our favor. Plant bug nymphs do not seem to handle hot, dry conditions very well. Particularly in the hatchling stage.

Reminder: The 65^th Alabama Cotton Scout Schools kicked off this week in Headland. We have a few more opportunities to go.

June 25^th: EV Smith Research Center (4725 County Road 40, Shorter, Alabama 36075)

June 26^th: McCord’s Fire Station #1 (1150 County Road 157, Centre, Alabama 35960)

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.

Wednesday, June 5, 2024

Tales of Cotton Insects: June 4, 2024

Plant Bugs Invading Alabama Cotton

Over the couple days, we have received multiple reports or observed adult tarnished plant bugs in April or early May planted cotton across central and north Alabama. In most cases, populations were below threshold, and a few squares were missing. However, some fields are at threshold and treatments are going out. Thus far, reports from southwest and southeast Alabama are that few or no plant bugs are being observed.

As our earliest fields begin to square, monitor pinhead square retention on the upper 2 or 3 nodes of plants. Our goal is to maintain 80% of these first position squares (closest to the mainstem). The reason to monitor the upper 2 or 3 nodes each week is that these are the “new squares” that were put on in the current week (added since last week’s scouting trip). In addition to monitoring square retention, a sweep-net is a good monitoring tool to determine the level of adult plant bugs in the field (threshold is 2 adults per 25 sweeps). Even if square retention is above 80%, we recommend treating adults because they will start feeding on pinhead squares and depositing eggs that will hatch in the following 7 to 10 days.

Our general recommendation for adult plant bug control is the high rate of imidacloprid or 1.75-2oz of Centric. In some areas, bifenthrin is also an option. In cases of high pressure, acephate may also be considered or tank-mixed with imidacloprid. We generally try to stay away from acephate and bifenthrin to preserve better beneficial insects and for resistance management, however under heavy pressure we need to worry about plant bugs and deal with other issues if/when they arrive.

Based on our observations in daisy fleabane this spring, we suscept this could be a multiple spray year for adults in June, particularly for early planted cotton. Remember that as long as square retention is at or above 80% a previous application “did its job” and more adults have moved into the field. Also keep in mind that June applications for adult plant bugs can set the tone for the rest of the season. By knocking back adults, we are reducing egg lay and nymphs that hatch out later as blooms begin to appear.

Reminder: The 65^th Alabama Cotton Scout Schools kicked off this week in Headland. We have a few more opportunities to go.

June 11^th: Associated Growers Gin (15031 Brownsferry Road, Athens, Alabama 35611)

June 25^th: EV Smith Research Center (4725 County Road 40, Shorter, Alabama 36075)

June 26^th: McCord’s Fire Station #1 (1150 County Road 157, Centre, Alabama 35960)

Monday, May 20, 2024

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.

Friday, May 3, 2024

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.

Adult differential grasshoppers

Cotton seedlings damaged by grasshoppers

Thursday, April 18, 2024

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.

Monday, April 8, 2024

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.

Friday, September 15, 2023

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.