Critical Period for Bollworm Escapes on 2 Gene Cotton in AL

Ron Smith

Extension Entomologist, Auburn University

We are entering the most critical period of bollworm presence during the next 20 days (July 15-Aug 1). This increase in bollworm activity began last week (July 9-13) along the Gulf Coast and the Mobile/Santa Rosa County (Jay) FL area. By July 20^th, we should see an increased bollworm egg lay in Central AL (Montgomery, Prattville, Selma areas). By the 25^th this increase may reach Cherokee County in the northeast, and by August 1^st the Tennessee Valley area of northern AL.

Increased bollworm moth presence was noted last week as far north as Pike and Barber County (Troy) area. This increased moth activity will be influenced by the planting date and acreage of corn planted in a given region of the state. Most all bollworm were corn earworms in corn previous generation. This life cycle is about 30 days and the eggs in corn were deposited during the white or pink silk stge. About 30 days later these moths that emerged from corn are looking for their next host. Cotton is the best host they will find in AL (not soybeans or peanuts).

Many (but not all) fields in all areas of the state had more worm damaged bolls in 2017 than we had seen since 1995. If we want to prevent this from happening again, the next 2 weeks are critical.

I assume that most realize now that our 2 gene cotton has lost some level of effectiveness against the bollworm species. When resistance is a factor, the problem usually gets worse over time—it seldom gets better.

Now, what should fieldmen be looking for?

1.     Eggs in terminals or on the fruiting structures: square bracts, white or red blooms (threshold on 2 gene cotton is 20 eggs/100 plants)

2.     Damaged squares in the upper canopy – may find more damage to small squares near the terminal in Phytogen varieties (5% damage is threshold).

3.     Newly hatched larvae

May find in small squares in Phytogen varieties

May find more in open white blooms or underneath red or dried blooms in Delta Pine and other varieties

(5% of plants with small larvae is threshold)

These small larvae are white when they have just hatched and will turn pale green within a day or so.

One thing that makes them stand out in a white bloom is they will have a black or dark brown head. Often the head is the best thing to look for since being dark stands out from the white bloom petals. (See Picture)

Once a significant increase in eggs or small larvae are detected—do not waste more time in the field. Get the word to the grower and get the sprayer loaded. Every 24 hour period that passes from detection to treating means less effectiveness with your insecticide. Also note that these bollworm moths will likely seek out our oldest and most promising cotton to deposit eggs in.

Now what treatment options do we have? Basically two. We can try the older chemistry, pyrethroids, or we can go to the newer chemistry, Besiege and Prevathon.

Things to consider here: bollworms have shown levels of resistance to pyrethroids in many areas of the cotton belt. However, the pyrethroid chemistry is much less expensive. Pyrethroids have about a 4-5 day residual on bollworms, where they are still active.

The newer chemistry Beseige and Prevathon have about 10+ days of residual on bollworms, depending on the rate applied.

If using pyrethroids, I suggest the highest labeled rate. If using Beseige, I suggest 8-9 oz/ac. If using Prevathon, I suggest 16-18 oz/ac. Besiege contains a low rate of Karate pyrethroid in the mixture. If you need tarnished plant bug or stink bug control, you will need to add about 1 oz of additional Karate, or equivalent pyrethroid, to the tank mixture. Prevathon has no activity on plant bugs or stink bugs.

In summary, this is the time to be ready to react to bollworms in 2 gene cotton. I will be tweeting as I hear of increased pressure in a region, county, or area.

I will be conducting tests on thresholds, timing, and chemical choices at our research farm at Prattville in Central AL, so will be in the field a lot within the next 2 weeks or so.

Stay in touch with the Syngenta Pest Patrol reports for up to date observations on bollworms. To sign up for the Syngenta Pest Patrol Updates for Alabama, register online at syngentaus.com/pestpatrol or register via text by texting pestpat11 to 97063.

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Thoughts and Tips for Bollworm Scouting on 2 Gene Cotton for 2018

          If you had an economic problem with escape bollworms on 2 gene cotton in 2017 and anticipate the problem in 2018, consider a 3 gene variety. Select one with similar maturity and yield potential as those you've been planting. This reduces acres scouts/consultants must focus on escape worms.

         When planting 2 gene cotton in 2018, monitor for bug and sucking pests and only make in-season foliar sprays when economic damage is found. This will conserve beneficial insects and reduce escape bollworms.

          If monitoring 2 gene cotton in 2018, take note of the corn planting window in your area. This plays a large role in the emergence & movement of corn earworm (bollworm) moths to cotton in July & Aug. The more corn planting is spread out, the wider the emergence window of bollworms.

          Bollworm moth activity isn't constant throughout the season. Instead it occurs in cycles especially through July. By August, generations of bollworms & tobacco budworms overlap. Fieldmen should detect the start of these peaks by focusing on eggs & newly hatched larvae in terminals/white blooms.

          Based on my observations during the Bt cotton era of the past 20 plus years, escape bollworm larvae do not feed on or damage as many fruiting sites per worm as they did in the pre Bt era.

          Scouting intervals for bollworms should be reduced to 3-4 days during critical windows on 2 gene cotton in 2018. Fieldmen may monitor select sentinel fields of similar variety and planting date to detect increased activity.

When monitoring for bollworm larvae or eggs on 2 gene cotton in 2018, be more concerned about detecting population increases early, and reacting if necessary, than quantifying exact numbers-- for example: 18 vs. 28 per whatever.

Fieldmen should consider damaged fruit on 2 gene cotton in 2018, but treatment decisions will be more timely if primary focus is on eggs and/or newly hatched larvae.

In order to stay on schedule in 2018, fieldmen should consider only staying in a field long enough to make a confident treat or not treat decision.

          Pest Patrol Updates on crop insects in Alabama available again in 2018. These alerts, sponsored by Syngenta, are beginning their 10th consecutive season. University entomologists discuss current conditions and advise on insect management.

        To sign up for the Syngenta Pest Patrol Updates for Alabama, register online at http://www.syngentaus.com/pestpatrol  or register via text message by texting pestpat11 to 97063.

Late July/Early August Cotton Insect Situation in Alabama

What are we currently finding in Alabama cotton fields? Plant bugs, both the tarnished and clouded species, have finally reached threshold or treatment levels in April planted fields that have not been sprayed. Some level of brown stink bugs can also be found in these same fields. A bug clean up spray would be advised for most cotton that is in the fourth or fifth week of bloom. Peak numbers of squares and bolls are currently at risk. Cotton planted after about May 10 missed most of the plant bugs this season. In central and south Alabama, there are very few plant bugs currently present in wild host or other crops. In other words, there are no more plant bugs in the landscape to migrate to cotton in 2017 in that region.

Between July 24 and 28, numerous field people from all areas of the state were contacted about escape bollworms on cotton with caterpillar technology. As of July 31, no none has reported any problems. We have conventional cotton on research stations in several areas of the state. Some level of bollworms and damage can be found on this cotton. The corn earworm flight from corn began about July 15 and has likely already peaked. Tobacco budworms will enter the mix during the month of August, but they will not be part of the "escape" situation in August. However, fieldmen should continue to monitor closely for escape bollworms. In Alabama, I would suggest we try the pyrethroid chemistry first if escapes are found.

Spider mites came into the picture about the third week of July in the Tenn. Valley area. Mites will likely show up in other fields statewide if we ever experience a 7-10 day period between rain events. Abamectin will provide the most economical control of mites. Whiteflies may occur in late season on our late maturing fields. If whiteflies are observed, I would recommend we use pyrethroid chemistry for stink bugs since Bidrin seems to aggravate the whitefly situation.

We will likely see stink bug numbers increase as we move into August and even September in our late maturing cotton. The southern green stink bug will make up a greater part of the population in coming weeks. This gives us the flexibility to choose either pyrethroid or phosphate chemistry. For weeks 3 through 6~7 of bloom, we recommend a 10% internal damage boll threshold for stink bugs.

Thus far in 2017, insects have not been a major limiting factor in Ala cotton production. Let's hope we can keep this trend going for several more weeks.

Insect Update for the Week of July 7

A combination of adult tarnished plant bugs and clumping aphids are being reported from more fields and areas around the state each day. Overall, little rainfall has fallen in about two weeks. Therefore, crops, especially corn and cotton, are under some level of stress. Therefore, most growers are choosing to target both plant bugs and aphids with this application.

I have not had any calls on mites in the past few days but that does not mean that populations are not building in select fields. So far, abamectin at 10 oz. per acre has given good control on mites in treated fields.

Immature plant bugs are present now in the oldest cotton. I have observed several fields where a threshold of three immatures per 5 feet has been recorded on a black drop cloth. When plant bugs become imbedded in cotton in July (all stages present – eggs, immatures and adults) quite often multiple applications are needed to bring the population under control. For those that want to use the IGR Diamond, now is the time to do so. An adulticide plus Diamond, at 6-9 oz. per acre, should give control of the population for 14 plus days. It is my opinion that most of the adult plant bugs have now left wild host plants and are now in cotton. We just don’t seem to get that many moving from corn here in Alabama.

Moth traps in central Alabama captured an abundant number of both bollworm and budworm moths last week. 2014 may be the year that fieldmen, consultants, and scouts really prove their worth. There is just no way to time the appropriate chemistry at the proper time without someone monitoring insects. This looks like an above average insect year for cotton and we haven’t even reached the primary stink bug window yet. In sweeping for adult plant bugs last week, I was capturing brown stink bugs in about every set of sweeps.

Final Insect Update of the Season

The Alabama row crop insect control season is rapidly winding down. The few areas that still need attention for a few more weeks are as follows. We need to protect bolls on June planted cotton from stink bug injury until the bolls are approximately 25 days old. We still have plenty of time left in the season to mature small bolls that are present from blooms the last week of August. On soybeans, stink bugs continue to reproduce and feed on pods. Late planted, June to early July, soybeans will be susceptible to stink bug feeding for several more weeks. Stink bug adults will leave other crops when they mature and seek out late planted soybeans as their last host before heading for overwintering sites. I expect to see high numbers of stink bugs in many of these late maturing soybean fields. The good thing is that one application to economic levels of stink bugs in both cotton and soybeans made now should hold populations below damaging levels for the remainder of the season. Stink bug populations currently contain both the brown and southern green species. A high rate of most pyrethroids on soybeans should give adequate suppression. Kudzu bug adults are still present in many soybean fields but they are not as numerous in most fields as they were back a month or so ago. Their numbers seemed to have peaked in April and May planted beans back in the late June to early August window.

Overall 2013 has been a light insect year in Alabama for most species. A summary of what I have observed is the following. For cotton, thrips were moderate to heavy. However, their movement from wild hosts to cotton occurred in May instead of April. Therefore, their damage period coincided with our mid-planting period cotton instead of the earliest planted as happens most seasons. Plant bugs, aphids and spider mites were very light overall. Bollworms and tobacco budworms were low to nonexistent, even in fields of conventional cotton. I have conventional cotton on three research stations spread across the central and southern areas of Alabama. One had to search very hard all season to find a single larva or damaged fruit. Stink bugs were the only cotton insect that occurred at damaging levels in most fields in-season.

In soybeans, Kudzu bugs were extremely heavy in many early planted soybean fields. This was the first year that many soybean growers have had to deal with the Kudzu bug. Others will likely have their first experience in 2014. When all is said and done, I believe we will be able to handle this insect with one, or at most two, well timed sprays. Late maturing beans will likely still see a big buildup of stink bugs in coming weeks as other crops mature and dry down. The foliage feeding complex of green cloverworms, velvetbean caterpillars and soybean loopers have been very light in 2013. This follows the most widespread infestations of the past 40 years last season. Podworms have been very light in soybeans for the past two seasons.

This has been a very unusual year rainfall wise. This may be the only season during my 41 years here as our Extension Entomologist where we had too much rain.

With these comments we will end our in season blogs unless something unusual shows up. I hope my comments have been helpful to those of you that are receiving them. Hopefully we can continue this blog, the Syngenta Insect Hotline, and our tweets during the 2014 season.

Stink Bugs Showing Up in Fields

Based on calls from consultants during the past seven days, most insect attention on cotton in Alabama has now shifted to the stink bug complex. This appears to be the appropriate thing to do since no other widespread destructive insect is being reported and a high number of stink bugs are being reported from all the major row crops. This began with wheat during the spring months. Stink bug numbers later shifted to corn. High numbers have been reported in recent weeks in peanuts, with increasing numbers being reported in both cotton and soybeans.

If we back up and review the situation since the end of the 2012 season, this is as expected. Stink bugs built high numbers on soybeans late last season resulting in a high level entering overwintering sites. This past winter was mild and we did not have the excessive high temperatures or extended drought this spring to limit a 2013 population build up.

This complex included both the brown and the southern green species. In the more southern counties within Alabama, the leaf footed bug is also in the mix. Leaf footed bug damage is identical to stink bug damage to cotton bolls. The important thing here is that, control wise, they are more like the brown stink bug. Phosphide insecticides do a much better job in controlling brown stink bugs and leaf footed bugs than do pyrethroids. Growers will need to keep this in mind as they select their chemical for treatment decisions. In Alabama, escape bollworms on Bollgard and Widestrike cotton varieties have not presented a big enough problem to select a pyrethroid over a phosphate for stink bug control. Field monitoring between July 20 and August 10 will determine if that trend holds true for the 2013 season.

In a few weeks, as we begin to make more stink bug control decisions in soybeans, we will have to work more with the pyrethroid chemistry to suppress the brown stink bugs in the complex. Research trials across the south point to bifenthrin as their superior pyrethroid for brown stink bugs in soybeans. We can improve the percent control by using the higher labeled rates.

Back to cotton, here is how we suggest making treatment decisions. First, select a minimum of 25 ten to twelve day old bolls that are still soft to the touch and can be crushed by hand. Select more bolls from at least two locations from larger fields. Crush these bolls and observe for internal injury. Note, it may make this process faster by first separating the bolls with external feeding signs from those that have none. First, crush the bolls with external feeding only and determine the percent that have internal injury. If a threshold is reached, then the remainder of the bolls with no external feeding signs will not need to be crushed. Internal damage may consist of one or more warts on the inside of the boll wall, damaged seed or stained lint. Second, the decision maker needs to know how long that particular field has been in the blooming stage. Most stink bug injury and loss is coming during weeks three though five or six of bloom. This is the period when most harvestable bolls are being set.

In Alabama, I suggest using a 10% internal damage threshold during weeks three though six of bloom. An insecticide application will usually suppress stink bug numbers for seven to ten days unless a field borders another untreated crop with high numbers of stink bugs. If has been my experience that stink bugs do not move rapidly across fields like plant bugs as they reinfest. The first four to ten rows adjacent to corn or peanuts seem to get most of the migration initially.

In our heaviest stink bugs years, cotton in the coastal plains of the southeast have required up to four applications. Under most conditions however, only two or three sprays may be warranted.

One last thing I will mention today is that, in the past, stink bugs seem to cause more internal boll damage in wet seasons than in dry seasons. That being the case, and unless the weather changes, we need to be extra cautious of stink bug damage to cotton in 2013.

Update for the Week of August 19

Our April-planted cotton is beginning to open, and has varying levels of boll rot due to the weather the past 7-14 days. This same weather pattern of frequent thunderstorms and overcast conditions has been ideal for the spread of leaf spot diseases in out late planted cotton.

Insects have been light-to-nonexistent in recent days. There are a few plant bugs present and stink bug numbers have increased in some fields. I am not sure if either are at damaging levels, especially the plant bugs.

I believe we could safely say that leaf spot diseases are potentially more important than insects for the remainder of the season.

Growers who have peanuts or soybeans should monitor these crops carefully for the remainder of the season. Peanuts are attractive to a number of foliage feeding insects – including loopers, fall armyworms, bollworms, budworms, green cloverworms, velvet bean caterpillars and cutworms. Two peanut fields in Monroe County were identified last week with a high infestation of the garden fleahopper. To my knowledge this is the first time for this insect on peanuts. I am not sure what kind of damage potential they present. However, in cotton this pest can cause extensive foliage damage by leaving all leaves with stippling type feeling.

This same type of damage in peanuts would seem to be just as economic as a foliar disease.

Soybeans would be susceptible to damage from all the leps mentioned under peanuts plus the pod feeders – podworms and stink bugs. Many of our beans are late, planted behind wheat, and were just in full bloom the past 10 days. These beans will be susceptible to insect injury for weeks ahead. Only by scouting will growers know when economic insect losses are occurring and when controls are needed. We already have some fields in Baldwin County with damaging levels of soybean loopers. Foliage loss was as high as 35% last week when I made surveys in that area. Soybeans will be the last crop that stink bugs are attracted to this season. Even though it has been a light stink bug season, if they all accumulate in soybeans late season, controls will likely be needed.

I have heard little from the Kudzu bug on soybeans after finding them in the northeast counties of Cherokee and Cleburne back in July. Follow up surveys are needed in that area whenever time permits.

As the season winds down we will get back with further updates as new information becomes available and the situation changes.

Update for the Week of August 5

We are now in the home stretch, as far as insect control, in most fields of April planted cotton. Overall, there are a few things that I would be on the outlook for this week.

Stink bugs pose the greatest threat to most fields for the remainder of the season. Numbers vary greatly from field to field and in many cases from area to area within fields. For this reason, surveys must be thorough enough to detect the overall situation in each field. A dozen or so bolls will not accurately reflect the true infestation in most instances. Remember to select or sample 10-12 day old (quarter diameter) bolls. First separate out those with external damage from those with no external feeding signs. Second, crush those bolls with external damage and observe for internal injury. Our recommended “dynamic threshold” ranges from 30-50% internal damage early in the blooming period down to 10% during weeks 3-6 of bloom. This low threshold corresponds to the period when a high percentage of the total bolls are being set. Later into the blooming season, which is where many of our fields are now, we can relax our treatment threshold back up to the 30-50% range.

Now onto some other pests:

The mid-to-late July bollworm flight was maybe the lowest in modern times. Bollworms have been almost non-detectable in fields in central, SW and SE Alabama, even in cotton with no genetic technology.

As to tobacco budworms – while at the Wiregrass Research Center (SE Alabama) last week, numerous TBW moths were observed. This matches up with reports from SW Georgia that indicates an extremely high budworm flight going on in that nearby location. This will not be anything of concern for   Bt cotton but this could be a very significant event for peanut growers and even soybeans.

No questions were received concerning spider mite control last week. However, I personally observed mites in numerous fields that have not historically had mite infestations. They are present in many fields and their explosion will be greatly influenced by temperature and moisture for the remainder of the season. Growers treating for stink bugs would be wise to select an insecticide that is least likely to help flare mites.

With these thoughts we will end today and get back with another update as conditions change.

Update for the week of July 29th

The dominant question last week was concerning spider mite control. Several calls were received from consultants or agri fieldmen in the southern part of the state. Their question was not so much what to spray with (chemical choice) but instead when to spray. Most were scheduling stink bug sprays within a few days and wanted to know whether to add a miticide or not. Without seeing the fields, that is a difficult decision to make over the phone. My thoughts were that it could depend somewhat on how widespread the mites were in the field, the level of mite infestation and maybe most importantly – what is the weather outlook for the next 7-10 days.

Mite populations seem to hold steady in good rainfall patterns but explode during hot-dry weather. Even though we have had scattered thunderstorms for the past several weeks, there are many places where no rainfall has occurred. Last week was hot, mid 90’s or higher all week, so mites likely increased in number.

My suggestion would be to go ahead and treat mites if the weather outlook is for hot dry weather for the next 5-7 days. Most of our mites controls this season have been with abamectin (Agri Mek) at 8 oz/ac and results have been good.

Stink bug populations are still hanging around, in low numbers in many fields. However, from personal experience in a plant bug trial area in central Alabama that is located adjacent to corn, stink bug numbers have exploded in the past two weeks. Both brown and southern green species are well above the threshold level on the corn-cotton borders. Where cotton yields are promising and quarter diameter 10 day old bolls are still developing, stink bugs should be watched closely and controlled when above threshold. Cotton is at various stages now so our “dynamic threshold” would depend on where we are in the blooming-boll development cycle. Remember that 10% is our suggested threshold from weeks 3 through about 6 of bloom.

One other call was received last week concerning one or more fields in Baldwin County (Gulf Coast) infested with damaging levels of the garden fleahopper. We had several fields in recent seasons with this pest in the Mobile county area. The GFH seems to be primarily a foliage feeder but can damage every leaf in a field.

As of this date the bollworm/budworm complex is almost non-detectable, even in cotton with no caterpillar technology.

Update for the week of July 22nd

The past 7-10 days has been about as quiet insect wise as I ever remember for that time of the season.

Insect wise, we still have a few scattered Tarnished Plant Bug adults and a few immatures in some unsprayed fields – but I am not aware of a single field that has economic or treatable levels. In many instances where I have actually monitored fields, I found that part of the plant bug population is the clouded plant bug species. This species has been present in some fields in Alabama for most of the month of July.

Spider mites are still hanging around but have not exploded in recent weeks. The weather in the form of multiple thunderstorms appears to have slowed mites. Speaking of weather, some areas of the state have received multiple rain events of one to two inches or more while others have received only tenths a few times. Cotton ranges from as good as it has ever looked to knee high and blooming out the top depending on the planting date and the amount of rainfall received. In general, the earlier planted cotton that was stressed due to the heat and drought in May and June offers the least yield potential.

Back to insects now – a few stink bugs, mostly brown, are present in most fields. However, the numbers do not reflect the level we anticipated following a mild winter and the number seen on wheat at harvest time. It appears that the hot dry weather last month took its toll on stink bugs also. Boll damage to stink bugs is less than 10% in many fields. Cotton maturity ranges from the third week of bloom on late planted cotton to probably the sixth or seventh week of bloom on earlier planted fields.

Since we are at least at the third week of bloom, growers might want to consider a clean of spray for subthreshold levels of plant bugs and sink bugs in fields that have not received a foliar insecticide application yet in 2012.

This used to be the time we could also catch some escaped bollworms with this clean up spray. However, at this point, the bollworm flight statewide is very low and escaped worms are almost non detectable. Still the bug complex alone could help justify a clean up spray.

This is the way we see it on July 24, we will be back with an update as the season unfolds and conditions change.

Pest Update

The dominant factor in cotton the past one to three weeks has been the drought and heat. The weather has impacted both the crop directly and management decisions for insects. Some localized areas received rainfall on July 1 or 2. However, most cotton remains under stress from lack of moisture.

Aphids are the insect of primary concern since populations have built in many fields, putting additional stress on plants. Most growers delayed treatment decisions for aphids until this week – waiting for either rainfall or natural diseases. However, many are wisely spraying for aphids this week.

In some fields plant bugs are also present. Adults have diminished statewide but immatures have begun to emerge in many fields. I have also noted the presence of fleahoppers (both adults and nymphs) and clouded plant bugs in the mix. Field men have reported a large increase of bollworm moths in southwest Alabama fields this week.

Another significant even in row crop insects occurred during the past week. Kudzu bugs were observed feeding on soybeans in numerous fields in Cherokee County and in other fields in north Cleburne County and near Collinsville in Dekalb County. This pest has the potential to dramatically impact soybean production in Alabama as it already has in Georgia, South Carolina and North Carolina. First of all, soybeans will need to now be “scouted” as cotton has been since the late 1950’s. Mid-season (July) sprays will likely be required which will open the door for greater problems with podworms. Additional later sprays for the Kudzu bug will also be necessary. We will talk later about scouting techniques, thresholds and the selection on appropriate chemistry.

Overview of 2011 Cotton Insect Season

Early Season Pests
Thrips were extremely heavy from about April 15 to May 20. A major contributor to this heavy migration of thrips from wild hosts and wheat into cotton was the extreme drought conditions and absence of rainfall events during this period.

Plant Bugs
One peak movement of adult TPB into cotton occurred between June 20 and July 1. The majority of this infestation only happened in the earlier planted fields (most mature cotton). One insecticide application was targeted to these adult TPB’s when they were detected. Few immatures were detected in these fields in the coming weeks, so no in-field generation occurred. This may have been influenced by the extreme temperatures that occurred during this period (98-102⁰F).

Bollworm
Subeconomic numbers of bollworms occurred over an extended period from about July 15 to August 10. Few fields ever reached treatment threshold. 2011 was like the lowest bollworm pressure year on record. End-of-season damage boll counts on untreated genetic cotton were less than one boll per 10 feet.

Tobacco Budworm
Budworm numbers were non-detectable to extremely light all season long. Budworm larvae were too low to detect on conventional cotton and even on attractive crops such as tobacco when used as a sentinel crop.

Aphids
Aphid numbers were very slow to build in 2011 but also slow to crash due to naturally occurring diseases. The fungal disease was slow to develop which left aphids in the system much later than normal. Aphids normally peak and crash prior to, or at, the early boll set stage but this did not happen in 2011. Also, observations indicated a resurgence of aphids in the mid canopy area of the plants in late season as opposed to the terminal area.

Stink Bugs
Stink bugs in 2011 were fewest in number and damage of any year since the boll weevil was eradicated. This was likely due to the colder than normal winter temperature effect on the southern green species and the extreme spring heat and drought effect on the brown species. The majority of the few stink bugs observed in 2011 was the brown species.

Fall Armyworms
The “rice or grass” strain of the fall armyworm was abundant over much of the season in pastures, hay, and grasses. This strain will feed on peanuts but not on corn or cotton. They are easy to control on pastures with pyrethroids and numerous other labeled agricultural insecticides.

Impact of Alabama Cotton Commission Research Support for Cotton Insect Management-30 Year Overview 1986-2011

Thirty years of cotton insect research in Alabama— from boll weevils to boll weevil eradication– to beet armyworms and pyrethroid resistant tobacco budworms– to genetically altered varieties– to boll feeding bugs (stink bugs). On the chemical arsenal side– from Azodrin, EPN + methyl parathion, Lannate, Bolstar, Curacron, Galecron, and Fundal and the original pyrethroids (Ambush, Pounce, and Pydrin) to generics of the third generation pyrethroids.
 
What an evolution and what a ride. Thanks to support by the Alabama Cotton Commission, we have survived and are better for it.

One could argue that the past 30 years have been the “worst of times and the best of times” in cotton insect control. I consider it to be the most exciting and revolutionary period in cotton insect control history. The worst of times was the period of 1987 to 1995 with uncontrollable beet armyworm outbreaks and the development of pyrethroid resistance to the tobacco budworm. The best of times was made possible by the eradication of the boll weevil and the introduction of genetically altered cotton varieties. The “best of the best” times were experienced by many growers in 2011, with one of the statewide highest yielding years in history, the best market prices in my career and the lowest insect loss year in history. Both Alabama and the U.S. reported total losses to insects in 2011 as 2-3%, the lowest ever recorded.
 
Two of the most important events in cotton insect control in the past 100 years happened during the past 30 years: boll weevil eradication and the introduction of genetically altered varieties. In 1996, the first year of Bollgard cotton, Alabama lead the cotton belt by planting 77% of our acreage to the new technology. I feel certain that this set a record in the adoption of new technology. This was the result of two factors, one much more significant than the other. The overriding factor was the pressure and damage by the tobacco budworm in 1994 and 1995. A secondary factor was impacted by funding by the ACC which allowed us to work with the Bt technology for four years before it was introduced. We felt very comfortable in recommended Bollgard varieties to growers based on four years of research experience.
 
Looking back at this 30 year period, we can see where research support by the ACC was involved at every turn and event during this historical period.
 
Let us look back now at some of the major insect events and advancements that happened during the past 30 years and discuss briefly how ACC projects gave answers to the most significant concerns and questions during this era. I will attempt to present these in chronological order.

 

A. Beet Armyworm Outbreaks

• No effective chemistry available
• Parasites and predators, if present, gave effective control-- but not possible during active eradication
• Experimental insecticide, Pirate, highly effective but not approved by the EPA for emergency use until too late (August 1995)
• The original efficacy work on BAW control with Pirate was done at Prattville Experimental Field with ACC support
• Meeting with EPA in Senator Heflin’s office- Washington D.C.

B. Pyrethroid Resistant Tobacco Budworms

•  Pyrethroid Resistant Tobacco Budworms
• No effective chemistry available
• 1994-1995 highest numbers in history, up to 5 larvae per plant
• Yield losses astronomical
• ACC funded research showed that a combination of Lannate + Larvin on 5-7 day schedule gave suppression

C. Transition from In-furrow to Seed Treatments for Thrips Control

• Grower adoption rapid due to convenience and safety
• Initially Cruiser and Gaucho
• Transition to complete-pak with nematode suppression, Avicta and Aeris
• ACC research showed that seed treatments were not as consistent as in-furrow, and often needed a supplemental foliar spray, especially if planting in the early season window. Also, that seed treatments were less effective than Temik for nematode and spider mite suppression

D. Introduction of New Caterpillar Chemistry

• First- Tracer (Spinosad)- soft on beneficials, great on Tobacco Budworm
• Later- Steward (indoxacarb), Prevathon (rynaxypyr)- long residual and rain fastness, Belt (flubendiamide)
• All much more effective on small worms and require good coverage (ground application superior to air)

E. Evolution of Genetically Altered Technology

• Bollgard
• Single gene
• Weak concentration of Bt in blooming zone of plant leading to mid season bollworm escapes under bloom tag
• Benefits of pyrethroids overspray in mid-late July for sub threshold level of multiple pests
• WideStrike
• Two gene
• Second gene effective on fall armywor
• Weak concentration of Bt in terminal (original work Beltwide was at Prattville
• Scouting technique must be different than Bollgar
• Under pressure, WideStrike required overspray with pyrethroid
• Bollgard II
• Two gene
• Reduced bollworm escapes by about 80-90% over Bollgar
• Broaden caterpillar spectrum over single gen
• Second gene has long term benefit in resistance managemen
• No refuge requirement
• Bayer Twin Link
• Two Bt insect genes and
• Caterpillar effectiveness between WideStrike and BGII
• Bollgard III
• Contains third insect gen
• Third gene not Bt so has different mode of actio
• Should provide long term caterpillar resistance managemen
• Lygus Genetics
• Early stages of developmen
• Evaluated 40 lines of genetically altered cotton for lygus in 2011, Prattville

F. New Generations of Pyrethroid Chemistry

• Early 1990’s documented that not all equal for fall armyworm control. Karate, bifenthrin (Capture) superior
• More recently developing data to show that bifenthrin not as effective on bollworm species
• Pyrethroids not effective on the brown stink bug; however, bifenthrin superior to other pyrethroids
• Some generic pyrethroids may not be as effective as the “brand” names

G. Evolution of the Shifting Insect Complex Following BWE and Bt Varieties

• Current low spray environment
• Development of boll feeding bugs and sucking pests (plant bug and stink bug complex, leaf footed bugs)
• Role of IGR Diamond for plant bug management
• Reemergence of spider mites as an economic pest of cotton (influenced by movement from Temik to seed treatments)

H. Stink Bug-Dominant Insect of Alabama Cotton

• Work to develop best scouting technique
• Now sample 10-12 day old bolls for internal injury
• Worked with other southeastern states to develop a “dynamic” threshold for stink bugs. One that considered the number of bolls at risk at a given point in the season

J. Insect Management in Conventional Cotton Systems

• Conducted research on which new insecticides provide the best caterpillar control
• How to best manage beneficials, plant bugs, and early mid-season pests
• Trials indicate that weed control costs similar in both conventional and generic systems
• Tobacco budworms are the budget buster in a conventional system
• Can make only one TBW spray per season with the savings from no insect technology fee
• Discovered role of fire ants in both conventional and generic systems

K. Role of Fire Ants in Cotton

• Are the dominant beneficial in Alabama cotton today
• Not only important in conventional systems but also reduces escapes in Bollgard and WideStrike (Example: Mississippi consultants spray BGII on % egg lay)
• Some chemicals suppress fire ants more than others (Centric, Steward, pyrethroids, imidacloprid)
• Dr. Tim Reed and I conducted a project at Prattville last season (Poster Presentation)
• Results show less boll damage on both conventional and genetic cotton with fire ants in system as opposed to no fire ants

Numbers on the side represent the number of worm damaged bolls per 45 feet.

Impact of Fire Ants On Bollworm
Damage in Alabama Cotton

L. Emergence of Sporatic Pests

• Grasshoppers have increased in importance in reduced tillage environment
• Pose risk to stands
• $$$ greater investment in front end of season production cost now compared to old days
• Immature G.H. easy to control, adults difficult
• Ideal timing is when “burning down” in early spring
• Most all labeled chemicals, including the IGR (Dimlin), work on immature at low labeled rates

M. Study of Bollworm Resistance to Bt

• Lab studies conducted by Dr. Bill Moar, who has since moved onto the Monsanto resistance management team
• His findings indicate that bollworms have the ability to develop resistance to Bt in the lab– but they usually are unfit for survival when they do so.

In Summary
The ACC did not fund all of every project completed over the past 20-30 years. However, your support often made it possible to be in a learning situation on insect outbreaks; new emerging pests/problems and on projects/trials that were not directly funded. Some of you may remember that my grants in earlier years were entitled “To look at New Chemistry and Technology and Determine Where They Best Fit in Alabama Cotton Production”. This allowed us to know more about the strengths and weaknesses of new chemistry/technology than even the companies bringing them to the market. Cotton insect research is unlike most of the other disciplines in that it requires much more hands on involvement. Often times, support from multiple sources had to be pooled to provide the labor and travel to conduct cotton insect trials. Fifteen to 20 trips to a research site are often required between planting and harvest. This is especially true with the genetic technology under development.

A final point I would like to make is that we in Extension have conducted basically all the cotton insect research since the early 1990’s without an Ag Research station counterpart. We feel that we have kept Alabama growers up-to-date and often ahead of the curve in cotton insect management, when compared to other states. Much of the credit goes to the support we have received from the Alabama Cotton Commission.

Weather and Insects Affect Late Season Cotton, Soybean and Peanuts

The greatest impact on cotton during the past two weeks has been the lack of rainfall. Drought and intense heat has resulted in the shed of all fruit less than 10 day old bolls from the terminals of plants. This will tend to shorten additional boll production by 2 to 3 weeks and will likely reduce the “top crop” by 200 or so pounds of lint in many fields. Rainfall in the next 7 days would still help fill top bolls that are not mature.

As the result of the above conditions, the insect control season, especially stink bugs, is about over. A few southern green stink bugs can be found in late maturing fields or “swag” areas that remain green in more mature cotton fields. Thresholds for these would be 30-50% internal boll damage on 10-12 day old bolls. A few fields would still profit from stink bug controls.

Tobacco budworms have been extremely low all season but field observations and pheromone traps indicate an increase in the past week or two. Also, bollworm moths are abundant this week in the southern counties of the state.

Soybean Insects- Soybean loopers are at economic levels of 5 or more per row foot in some Gulf Coast area soybeans. Chemical choices (in no particular order) are: Intrepid, Steward, Belt, Tracer and Besiege (Coragen and Karate). Dimilin will give good suppression and long residual. On cotton, the same can be said for Diamond.

Peanut Insects- Scouts reported a mixture of foliage feeding worms in peanuts in Monroe County (S.W. Alabama) about 10 days ago. Many of these were controlled or either they have cycled out by now. This mixture was dominated by bollworm and fall armyworm (grass strain) species. Also in the mix were a few green cloverworms, loopers, and granulate cutworms. Pyrethroids gave nice control of this mix.

Bollworm Pressure Remains Extremely High Across the Coastal Plains of Alabama and Georgia

Bollworm pressure has been extremely high across the coastal plains of Alabama and Georgia for the past two weeks or so. Untreated sentinel plots of conventional cotton in southwest Georgia, southeast and southwest Alabama have been stripped of all fruit during this period. Bollworm moths were still active on August 10th at Headland, Alabama. We are relatively certain most of this population has been the bollworm species because sentinel plantings of tobacco in this same area have had few tobacco budworms present to date. As far as I know, no economic levels of escapes have occurred on varieties with Bt technology.

Aphid numbers continue to build, while most insects numbers remain at moderate levels

Insect conditions have not changed greatly in the past week or so. Aphids have continued to build in more fields. All other insects are low to moderate levels (mostly sub-threshold). These include plant bugs (including a few clouded plant bugs coming into the mix), bollworms, tobacco budworms and stink bugs. Most growers do not have enough of a single species to apply controls for. The two biggest surprises at this point in the season are the low number of bollworms and the low number of stink bugs in most fields. Numerous fields of conventional cotton still have less than 2 bollworms per 100 plants. Boll damage to stink bugs is less than 10% in most fields.

Most of the state has had abundant thunderstorms for several consecutive weeks. Cotton yield prospects have improved greatly and, if conditions continue, numerous fields have two bale plus potential. The two biggest limitations we now have are fields with “skippy” stands and too much late maturing cotton.

Later than normal aphid buildup may require more proactive treatments

More fields were reported with aphid infestations last week. Due to this later than normal aphid buildup, growers may want to be more proactive in applying treatments. Stress from aphids, where they are occurring in 2011, is overlapping early to mid boll set. We need to set all the fruit possible in the next two weeks.


Both the brown and Southern stink green stink bug species are present at some level in many fields. Cotton planted in April and up to mid May is already into the third to sixth week of bloom. This means that we should be using a low (10%) internal damaged boll threshold for stink bugs. Growers who chose to treat for aphids should consider stink bugs when selecting their chemicals or tank mixtures.

The flight of corn earworms from corn to cotton usually occurs the week of July 20 in central Alabama. This egg lay may occur up to 7 days earlier in south Alabama and 7 days later in the northern counties. This budworm flight will only be meaningful to those who have planted conventional cotton varieties. Older larvae observed last week were likely from budworm moths that occurred 1 to 2 weeks ago.

Cotton Insect and Crop Report - Alabama 2010

Cotton was planted on 345,000 acres in 2010, an increase of about 25% over the previous year. Over 96% of the acreage contained the RoundUp gene and approximately 90% contain genes for lep control. Due to the phase out of DP555, market share was gained by Phytogen, Fibermax and Stoneville varieties.

Early season insect pressure (thrips, aphids, cutworms, grasshoppers and plant bugs) was below historical levels for the second year in a row and very limited foliar applications were necessary. More than 80% of the acres were planted with insecticide treated seed, with the remainder planted with Temik in-furrow. Midseason pests included bollworms, at below normal numbers, which dictated fewer oversprays over the varieties with stacked lep genes. Very few lep sprays were made statewide, even in fields planted to conventional varieties. 2010 was one of the lowest pressure years in history for all lep species.

Stink bugs were by far the most economic of all cotton insects. Two to four foliar sprays were needed over most of the state to hold damage below threshold level. The dominant species in 2010 was the brown stink bug, Euschistus servus. The stink bug complex remains a complex issue to many growers and fieldmen, especially as it relates to scouting techniques and thresholds.

Weather during the production season was good until about July 15-20 at which time rainfall ceased and temperatures increased to 96-102° F (days) and 78-82° F (nights) for the following two months. This combination of heat and drought took its’ toll on yields since only about 10% of the state acreage is irrigated. Therefore, an 800-1000 lb potential yield deteriorated to about 500 lbs. Certain fields in several regions of the state yielded as low as 200-250 lbs of lint/acre.

Research continued in 2010 with the newer chemistries against the bug complex, sucking pests, and leps. Also, the newer genetic technologies were also evaluated both, agronomically and entomologically, within the state.

Cotton Insect Loss Estimates Made

2010 was one of the lightest insect years on record. Loss estimates range from a total of 5.2% of yield in central and south Alabama to 3.6% in the Tennessee Valley region. Most of these losses were attributed to one insect (pest) in each region. For the southern region it was the stink bug, predominately the brown species (3.5%), and for the north it was spider mites (2.3%). Other insects that caused measurable losses were the bollworm (lowest in 38 years), plant bug, and thrips.

Twin Link Field Day

I had the opportunity to participate in the Bayer Twin Link dual-Bt technology field tour near Blackville, SC, on August 23rd. Research on this technology was observed on the Clemson Edisto Research and Education Center and on the Carolina Ag Research farm (Dr. Mike McCarty). Both locations have had some of the highest bollworm pressure I have ever observed. Untreated conventional cotton had 100% boll damage and some foliage loss to bollworms. The Bayer Twin Link Bt technology did not give perfect control under this level of pressure but showed impressive results.