Alabama Insect Situation: July 28, 2022

Cotton

Most of the reports we have received this week is that overall, we are in pretty good shape. However. There are some fields that are in need of reprieve. We have some fields in SW Alabama that cannot miss a rain, and other fields in N Alabama that cannot catch a rain. Cotton across much of central Alabama looks to be in good shape. We are hopeful for a good August and September so we can finish the crop out and maximize whatever yield potential we have in the field as of today.

Bug Complex

Not much has changed with the bug complex (plant bugs + stink bugs) situation over the past 7 days. Some fields are still requiring attention from plant bugs, but we are at the point with most of our cotton that we need to kill stink bugs when going across the field. We walked some fields today in S Alabama with a 2x threshold of both plant bugs and stink bugs. Many of these fields were missing lots of fruiting sites, but still have time to make a top crop if bugs are managed moving forward.

Our observations and reports have been that most fields sprayed over the past week to 10 days have not required follow up sprays. We typically expect to get about 2 weeks out of a stink bug spray before retreatment is necessary. This is not residual control, just typically about the time it takes another infestation of stink bugs to build to population levels that can cause economic damage (=10% internal damage). This may not be the case if sources of stink bug populations are nearby (corn, peanuts, pecans, etc.) and fields should still be monitored weekly to ensure damage is not building.

Spider Mites

Spider mite infestation in Headland, AL.

We have received reports that spider mites are requiring attention, primarily in the Wiregrass this week. Abamectin is typically the go-to for mites based on economics, but we wouldn’t normally recommend using abamectin as a follow up if retreatment is needed. There are pockets of resistance across the southern Cotton Belt and if abamectin doesn’t provide satisfactory control one week, I would not expect much to change the following week. We talked about alternative options in last week’s Blog (link).

Bollworm in cotton.

Bollworms

Thus far, the bollworm flight has seemed to be pretty low overall when looking at our trap counts across the state. Historically, the expected peak flight varies with South Alabama ≈July 10, Central AL ≈July 20 and North AL ≈August 1. However, we have received reports of egg lays varying from 1-10% in the TN Valley and high numbers of moths in fields in SE Alabama. In general, we do not recommend making insecticide applications based on eggs in Alabama, as we still rarely find escaped worms in our Bt cottons.

Peanuts

We are beginning to hear about infestations of defoliating caterpillars in peanut fields. Often, we have a complex of species including green cloverworms, soybean loopers, velvetbean caterpillars and some others such as fall armyworms, beet armyworms, bollworms, cutworms, or others. Our threshold is 4-8 worms per foot of row. The low end is advised when peanuts are small or stressed from other factors.

We also have received reports of lesser cornstalk borers (LCB) requiring treatment in the Wiregrass. This pest prefers fields with skippy stands and they thrive in hot, dry conditions. With the loss of chlorpyrifos (Lorsban), we only have a couple of options including chlorantraniliprole (Vantacor 1.2-2.5 oz), or chlorantraniliprole products pre-mixed with the pyrethroids bifenthrin (Elevest 5.6-9.6 oz) or lambda-cyhalothrin (Besiege 10 oz). Another option is the insect growth regulator Diamond (6-12 oz). Keep in mind that the weather conditions that LCB thrive in are the same the spider mites can blow up in as well. If spider mites are a concern, consider using products without the added pyrethroid as this may flare mites.

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 and monitoring fields to know what insects are at what levels. In Alabama cotton, stink bugs will be the most yield limiting insect we face for the remainder of the season. Be ready to treat when thresholds are reached. 

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: July 22, 2022

Cotton

From this point forward, the bug complex of stink bugs and plant bugs will be the most yield limiting insect situation we deal with. Stink bugs will likely be the dominate pest complex, but we are receiving reports of plant bugs still requiring attention in some fields across Alabama.

Bug Complex

We spent a lot of time in cotton fields across the state this week and stink bugs and their damage were easy to find. We are still seeing plenty of brown stink bugs as well as a mix of southern green (C and S AL), green (N AL) and brown marmorated (both) stink bugs. For the most part, southern green (SGSB), green (GSB) and brown marmorated (BMSB) stink bugs are susceptible to pyrethroids and organophosphates, while brown stink bugs (BSB) are less susceptible to pyrethroids, although using higher rates increases control. While our thresholds are based on internal boll damage done by stink bugs, observing the species in the field can help determine what insecticide is needed for control. The pictures below show the different species and how to identify them.

BMSB - Note white bands around antenna
and abdomen.

GSB - Note black bands around antennae.

SGSB - Note red bands around antenna.

BSB - No bands around antenna.

  

Stink bug damage.

Other Pests

We are receiving reports of aphid populations crashing across Alabama. The fungus is beginning to take over and populations are decreasing. At this point, we probably don’t need to worry about aphids anymore. A few fields are being treated for spider mites in NE and NW Alabama, but overall, we haven’t heard much about mites over the past week. Based on the latest US Drought Monitor report for Alabama, some of these areas were abnormally dry to in a moderate drought as of July 19 (link). If you are in a dry area and mites are present, keep in mind that populations are easier to control when they are caught early. If the bug complex requires attention, look for spider mite injury and the presence of active populations. Consider mixing in a miticide if populations are active and growing. Options include abamectin (0.15 EC formulation = 12-16 oz, 0.7 EC formulation = 2.6-3.5 oz), Zeal, Portal or Oberon.

Soybeans

Populations of kudzu bug have exploded this year. We have been getting reports and have seen huge populations. In most cases, eggs are hatching, and nymphs are beginning to emerge. This is the prefect time to treat. Most labeled pyrethroids provide excellent control of kudzu bugs.

Adult kudzu bugs with eggs and hatchings.

The stink bug situation in soybeans seems to be fluid. Some fields have threshold levels (4/25 sweeps) while others do not. More fields in the Black Belt region are being treated for redbanded stink bugs. This is a pest that we need to be aware of in soybean fields in Central and South Alabama. Nymphs have begun to emerge, and embedded populations are building. At this point, tank-mixtures are needed to control adult and immature populations. High rates of bifenthrin (1 gal to 25-20 acres – or 5.12-6.4 oz) plus 0.5 to 0.75 lbs of acephate is the best option for controls. Keep in mind that there are label restrictions for these products in soybeans. Bifenthrin can only be applied once every 30 days, while a maximum of 1.5 lbs of acephate (a.i.) can be applied per season. Other tank-mix options include neonicotinoid insecticides (imidacloprid, Belay, Endigo, Leverage 360) at the highest labeled rates.

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 informtaion 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 Message

It is time to start thinking about stink bugs in cotton at the 3rd week of bloom or older. Our threshold is pretty low during peak bloom (weeks 3-6) at just 10% internal damage. Be prepared to treat when necessary. Our goal for 2022 is to minimize losses to insects as best we can.

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: July 14, 2022

We have gotten some much needed rains in some fields in parts of the state, while other are missing rains still. A lot of the cotton we have seen in central Alabama appears to have turned the corner over the past 7 days and is looking good. In the north, we have seen some fields that looked great and some that needed rain desperately. In conversations with most folks across Alabama, the situation depends on which field you are standing in and what day of the week you are in it.

Aphids in cotton

Aphids have been the big thing observed this week. We have made observations and received reports of pretty high aphid populations building across the state. The good news is that we have also received reports of the fungus being “among us” in South Alabama. We can’t predict exactly when it will spread statewide, but it is on the way. We don’t always see a yield response from spraying aphids, unless the cotton is already stressed by something else, like drought. However, one thing to consider is the difficulty of scouting for other insects when plants are heavily infested, and honeydew is all over the place. Finding immature plant bugs on a drop cloth with hundreds of aphids is no easy task either. While we don’t normally recommend making a special trip for aphids, if you are already going over the field for something like a PGR application, I would consider dropping in a high labeled rate of imidacloprid for aphids, assuming plant bugs aren’t at threshold levels.

Speaking of plant bugs, most of the reports we have been receiving are that populations are spotty and that in many cases, nymphs are still very small and just beginning to hatch. Depending on the age of the cotton and size of the plant bug population, we may can go out with a “plant bug material” like Transform (1.5-1.75 oz/A). If high populations of plant bugs are in the field, Transform is the best option for control. If the cotton is still around the first week of bloom, that is also a good time to consider a tank-mix of the insect growth regulator, Diamond (6oz). As the cotton matures into the 3^rd or 4^th week of bloom, however, we need to go with something that will also kill stink bugs. We are expecting a heavy stink bug year and have already begun hearing about stink bugs requiring attention in fields of south Alabama. One other comment on Diamond and plant bugs. There are two ways to maximize the effects of this material. Number 1: apply it at the first appearance of nymphs. This ensures that we don’t waste any residual “on the front end” and maximize the ≈2 weeks suppression out of it. Number 2: Don’t spray another chemical that would control plant bugs during the following ≈2 weeks. If we are so close to the stink bug window that an application will likely need to be made in the next week, we will not have needed the residual of Diamond as long. Just a couple of things to consider when looking at insecticide budgets for 2022.

If we want to control the “bug complex” (plant bugs + stink bugs) we really only have a few options. Acephate (0.75 lb), Bidrin (6 oz) or bifenthrin (6.4 oz). Although stink bugs prefer bolls that are 10-12 days old (about the diameter of a quarter), they will feed on smaller “thumb-sized” bolls if few quarter-sized bolls are available (during early bloom). Keep in mind our thresholds are dynamic and vary during the week of bloom (see picture). To sample, pull a minimum of 15-20 bolls that are 10-12 days old (about the size of a quarter) from the field (not all from the border) from at least 2 areas within the field. Bust the bolls open and look for warts, stained lint, or “pinprick” marks on the inside of the boll wall.

If you need to pick up aphids and control bugs, consider adding imidacloprid to the bug complex materials above. Transform is an excellent aphid material and would not need a tank-mix for aphids but tank-mixing a pyrethroid if some stink bugs are in the field would be beneficial.

One final note. 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 informtaion 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: July 7, 2022

Cotton Insect Situation

We have been in a lot of cotton this week and much of it has needed a good rain (or two). The storms we have been getting across Alabama seem to end up being isolated and for whatever reason, dumping rain in the same areas (and missing the same areas) during each event that occurs. I am no agronomist, but I suspect these dry fields will not be needing a lot of PGRs in the coming days. Those applications may need to wait to see how the crop responds to a rain. In some fields, cotton appears to be in “survival mode” and is sending resources to the small bolls in the lower portion of the canopy instead of going back to vegetative growth after a rain event. Again, I am not an agronomist, just what an entomologist seems to be observing.

Plant Bugs

The black drop cloth is the best way
to sample for immature plant bugs.

Based on our observations and reports we have received from across the state, it appears we may be in the “lull” between adult and immature plant bugs. The extended dry period we experienced seems to have caused more of a single migration period into fields instead of a “trickle” or prolonged migration like we observed last year. Many of the adult plant bugs that infested fields have either died from insecticide applications or appear to have run their course naturally. Sometimes, we see a lag time between this happening and immature plant bugs (nymphs) hatching out. We did a lot of drop cloth samples in our cotton that is around first true week of bloom in central AL and in the TN Valley. Our observation was that had we been sampling a day or two earlier, we would have found even fewer bugs. Most of the nymphs we found were first instars (hatchlings) that are very small. In other words, most of these plant bugs were likely just a day or so old.

Keep in mind that plant bug nymphs are extremely difficult to find in sweep-net samples and the black drop cloth is the most effective way to sample. If using a drop cloth, we recommend treatment when you find an average of 3 nymphs per 5 row feet (1 sample). Additionally, some people use a dirty square or dirty bloom threshold of 10% injury.

We are currently at a good time to get the insect growth regulator novaluron (Diamond) in the mix. This chemical kills nymphs as they molt from one instar to the next and is most effective when applied at the first appearance of nymphs, which is typically around 1^st bloom in Alabama. We usually recommend a 6 oz rate, which we feel provides about 2 weeks of residual suppression. Most times, Diamond should be tank-mixed with a knockdown insecticide such as Bidrin (5 oz), Transform (1.5-1.75 oz), Bifenthrin (5-6.4 oz) or acephate (0.5-0.75 lb ai). This can help control any remaining adults and larger nymphs that may already be in the field. At this point in the season (post-bloom), we no longer recommend the neonics (imidacloprid or Centric) due to resistance management, pollinator protection and lack of consistent performance on nymphs.

Aphids on a cotton square

Aphids

We have also started hearing about aphids building in some regions of Alabama. Normally, we don’t see much a yield response from spraying aphids in our research trials, but this year may be one where that trend doesn’t hold up. In fields that are already drought stressed, we do see yield hits from aphids compounding that stress. Treatment is sometimes recommended when populations exceed 50 or more aphids per leaf and honeydew is accumulating, especially under drought stress. We normally clean up aphids with plant bug sprays and don’t need to make applications targeted only for aphids. I know we have some (very) late cotton out there this year. If aphids are building and the cotton is drought stressed, I would consider an application.

Spider mites in cotton

Spider Mites

Spider mites are one of the most difficult cotton “insects” to make a management decision on. This is because thresholds are not well defined, and weather plays a significant role in population development. Our recommendation is to treat when 30-50% of the plants are showing symptoms, mites are present, and no rain is in the immediate forecast (see what I mean?). Of all insect management decisions, this one probably requires the most professional judgement. Products with the active ingredient abamectin provide relatively good control. Coverage is important for control and as the crop canopy develops, higher rates of these products are recommended. Remember that populations are often worse following applications of broad-spectrum insecticides but they can build in fields that have not been treated recently as well.

Peanut Insect Situation

TSWV Symptoms in peanuts

The phone has been relatively quiet on the peanut front this year. We are beginning our TSWV surveys with our REAs across the state and are observing symptoms ranging from 3-9% infection so far in the Wiregrass. Of course, there is nothing we can do at this point to reduce virus incidence.

The hot, dry weather means that we are at a risk of lesser cornstalk borers in out peanuts, particularly in dryland fields. Dr Mark Abney at UGA posted a good article on LCBs on the UGA Peanut Website (link).

Soybean Insect Situation

We are hearing about stink bug populations building in soybeans. Mostly, these calls have been in fields at or around the R3 stage and no seeds are at risk. Ordinarily, we don’t recommend treatment for stink bugs when there are no seeds at risk. However, IF redbanded stink bugs make up a large portion of the population, treatment may be beneficial. RBSB are not doing much economic injury at this point, but populations are difficult to control once they are established and immatures are present. Knocking them back early may help. This application would need to be weighed with the risk of flaring other pests, such as soybean loopers, later in the season. We don’t have any data on the risk vs reward of that early of an application for RBSB, just some experience on how damage RBSB can be and how difficult to control they can be as well.

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: July 1, 2022

We have gotten some rains over the past week, although some of it was still isolated. Hopefully this will help kick the crop back in gear and get moving. We are starting to find more blooms, particularly in central and south Alabama, but we likely have some blooms in fields in the north as well.

Adult tarnished plant bug

Plant bugs are still the hottest ticket in town. Over the past few days, we have received reports of up 3-4x threshold populations in northeast (Cherokee Co.) and north central Alabama (Lawrence/Morgan Co.) and we have observed threshold populations in central Alabama and the Tennessee Valley as well. The common theme is older cotton and cotton that had not yet been sprayed for plant bugs. While fields that have been treated still have a plant bug here or there, we do not appear (as of yet) to be dealing with much re-
infestation of these fields. Reports out of the Wiregrass are that plant bug numbers appear to be relatively low. Some fields may have numbers and other do not. I spoke with our colleague across the line in Georgia, Dr. Phillip Roberts, he shared with me that while a lot of acres in central GA are being treated, folks are calling about low numbers in SW Georgia. So what we are hearing about in the Wiregrass (lower numbers) appears similar across state lines. We are hearing similar reports from the Southwest Alabama. The plant bug situation changes from field to field.

One thing to keep in mind is that plant bug pressure is often higher near field borders with corn. Corn is a good host for plant bugs. Typically, movement out of corn is expected around the time the silks begin to turn brown (R2 or the “blister” stage), but the movement could be before or after that stage depending on when the original egg lay occurred. Unlike with stink bugs, however, we do not recommend spraying corn for plant bugs. It just won’t help the corn (plant bugs are a non-pest), and plant bugs aren’t as “hemmed up” in corn like stink bugs.

In terms of treatment options, we still like the neonicotinoid products on migrating adult populations (imidacloprid or Centric). While these products, and particularly imidacloprid, won’t provide 100% control, they often provide enough to reduce populations below threshold and maintain square retention above 80%. As we get into bloom and start finding nymphs, we change from the neonics to chemistries like Transform, acephate, Bidrin or pyrethroids (depending on location in the state). Around 1^st bloom is also a good time to get Diamond in the mix. This insect growth regulator provides control of immature plant bugs and may be enough when combined with a knockdown insecticide to get us to the stink bug window (≈3^rd week of bloom).

Thumb-sized boll 
damaged by stink bugs.

Speaking of stink bugs, we are expecting this to be a heavy stink bug year. Our observations and reports from corn suggest high populations are out in the landscape currently. Although stink bugs prefer to feed on bolls about 10-12 days old (about an inch in diameter), they will feed on thumb-sized bolls if nothing else is around to feed on. The presence of stink bugs in early bloom cotton may influence plant bug material choices. Keep in mind our threshold for stink bugs during early bloom is 30-50% internal boll damage.

Even after the rains, we still have some spider mites in fields. Hopefully rains will knock back populations and let the cotton outrun them. Keep in mind that rain will not outright kill mites or eliminate them from a field. If you had some in fields prior to a rain, they can blow back up pretty quick if conditions allow. I am not sure that we have many fields that need to be treated for mites right now, but they are something to continue to monitor.

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