Insect and Crop Update for the Week of June 23

After going weeks with light to moderate thrips pressure, damage was heavy on 4-7 leaf cotton in early June, especially in SW Alabama.

Cotton was growing rapidly but thrips damage on true leaves was showing heavy damage from about the 4^th to 7^th true leaf. (Peanuts also were taking heavy damage during this same period.)

The thrips window is over now and we need to shift our focus to spider mites, aphids and the plant bug complex which includes tarnished plant bugs, fleahoppers and an occasional clouded plant bug.

Mites are primarily found in the TN Valley region of North Alabama and some treatments were being applied last week.

I noticed the first aphids on April planted cotton in central Alabama last Friday (June 21).

Plant bug numbers (adults) were down last week but nymphs are beginning to appear in our earliest planted cotton (mid-April). I would suggest using a sweep net to sample adults for the next 2-3 weeks, depending on the age of the cotton. As we approach first bloom I would switch to a drop cloth and concentrate on the presence of immature plant bugs.

Also, field men should now be looking at pinhead square set. Fields surveyed on June 21 were setting about 90% of the fruit. However, some plants had up to 30% square loss at that point. I believe you will find that migrating adult tarnished plant bugs will seek out the earliest planted and most lush cotton fields. My thought is that this cotton provides the best shade from the 95 degree temperatures, and is the best host for plant bugs.

While looking for pinhead square set I noticed a number of white eggs, likely tobacco budworms. They would not be a concern now, but in the old days it would have created a real predicament. Spraying for plant bugs during a budworm moth flight would have been expensive and also put the grower on a treatment treadmill for the remainder of the season. Sometimes we forget how well we have it compared to the pre-Bollgard years.

On another insect – a few stink bugs are already present in cotton. Normally we do not worry about stink bugs until about the third week of bloom, when we have bolls that are 10-12 days old. However, when stink bugs are present at bloom they will attack thumb sized bolls as soon as the bloom tag sheds. Any feeding to bolls this size will cause the boll to abort. Therefore, fieldmen need to be alert for adult stink bugs in early bloom cotton as they monitor for plant bugs with a sweepnet. Stink bugs will not damage squares or blooms but will seek out these first small bolls.

Since some of our corn was planted later than desired, stink bugs will likely remain with that host until the post roasting ear stage when the kernels become hard. At that time we may have a large movement into other crops such as cotton, soybeans and peanuts.

One word about Kudzu bugs on soybeans. Numbers of adults are out of site on many of our April planted beans. In fact, adult numbers are beginning to decrease in some fields now but numerous immatures are present, which is the trigger we use to treat the field. Fieldmen who have not experienced this insect may overlook these immatures when they are small. They will be a clear to greenish color and very small after hatching.

Insect Update on Cotton and Soybeans

As of 8:45 am Monday, June 10, all is quiet on the insect front. Rainfall during the past week has given cotton a growth spurt. Youngest cotton is 3 to 5 true leaves and overall has little thrips injury. Older cotton is at the 5 to 9 true leaf stage. Many fields are between the thrips injury stage and the stage where we begin to focus on plant bugs. This window is about 7 to 10 days long. Mid April planted cotton already has 2-3 pinhead or larger squares and should be scouted for adult plant bugs. No aphids or spider mites have been reported.

We will be conducting scouting schools in Autaugaville (central AL) and Headland (Wiregrass area of SE AL) this week. In addition to cotton and soybean insects (Kudzu bugs) we will also have presentations on cotton disease and resistant weed management.

Kudzu bug adults are attacking early planted soybeans in the Prattville, Tallassee and Auburn areas. At present our treatment threshold is 5 adults per plant.

Plant Bug Surveys in Wild Hosts

Historically, years of abundant spring rainfall resulting in delayed cotton planting have been some of our highest plant bug damage years.

Plant bug damage can be more pronounced when the migration of adults from wild host plants occurs prior to or about the time cotton is setting the first pinhead squares (6^th to 8^th true leaf). One reason for this is that when adult plant bugs feed on pre square cotton they feed in the terminal or growing tip. This feeding can disrupt the physiology of the plant causing abnormal growth (crazy cotton). This abnormal growth can delay fruiting for several weeks.

On May 20, I surveyed one of the primary spring host plants (daisy fleabane) for tarnished plant bugs in Alabama. On that date in Henry County (southeast Alabama) I found that about one-half of the plant bug population was dark (older) adults about ready to migrate to a new host. In past years, cotton is about the only host that is attractive at this time of the spring. Most wild spring hosts are now drying down. The remaining one-half of the population on May 20 were immatures of all stages. This means that the migration to cotton could be extended for a several week period which is common in wet springs.

On May 30, I made a second survey in the same area and found fewer immatures but more light colored younger adults. This may indicate that the older adults have moved to a new host already and some of the immatures are now young adults. I made a second survey on daisy fleabane on May 30 about 80-90 miles farther north than the first one. In this survey I found that they majority of the population was still immature. The fleabane was still greener and fresher at this location which means the plant bug population was in perfect sync with the host plants.

Only time will tell what this means in 2013. However, scouts, consultants and field men should be alert for the presence of adult plant bugs in cotton, and specifically late planted cotton, in the next 10-30 days.

Cotton Growing and Thrip and Grasshopper Treatments

Some of the April planted cotton is finally beginning to grow since the nights have become warmer. April 17 planted cotton at Prattville, AL now has 4-6 true leaves and is about 5 inches high. Thrips pressure is still heavy enough to cause a moderate level of visible injury to true leaves when no foliar insecticide was applied. Most cotton planted in April 2013 definitely needed a foliar spray at the 1-2 true leaf stage. Plants that emerged after May 15 likely will not need this foliar application.

I have had several calls this week about making a combination spray to target thrips and grasshoppers as an over the top herbicide is applied. My comment was positive to do this but realizing that some of the grasshopper population is now adults and will be difficult to control without going to the highest labeled rates of whatever insecticides are applied. I suggest staying with a lower rate and just targeting the thrips and immature grasshoppers.

I will come back in a few days to look ahead at out next potential cotton insect – tarnished plant bug. It has been my experience that wet springs, with delayed planting, have the potential to be bad plant bug years.

Update for Week of August 26

The cotton insect control season is basically over. I say that realizing that there are a few late maturing fields within the state that may still need a stink bug spray. There are even fewer fields that have high numbers of tarnished and clouded plant bugs present. Where growers are attempting to make a top crop, in fields that have exceptional yield potential, plant bug controls may still be applied. Our greatest concern now in cotton is boll rot and disease. The past few days of overcast skies and rain showers have increased boll rot. The next weeks forecast is much the same. Other than a few southwestern counties, the state was spared from the excessive rainfall from Isaac.

At present, the insect action is primarily happening in soybeans and to a limited degree in peanuts. The lep feeders are occurring on soybeans state wide. We have more soybean loopers on beans in the Tennessee Valley area of North Alabama than I can ever remember. This complex also includes the green cloverworm statewide and the velvetbean caterpillar as far north as Selma and Montgomery in central Alabama.

Loopers, (all are the soybean looper, more difficult to control) are occurring at 1 to 8 or more per sweep. Most of our beans are drill so we cannot use a drop cloth. Our threshold experience with loopers using drop cloths is well established at 5-8 per row foot. We are wrestling with a sweep net threshold. Two loopers per sweep are not causing more than 5% foliage loss while 8 per sweep is causing 30-35% foliage loss. Our threshold is 20% foliage loss with beans at the stage they are now. So somewhere between 2 and 8 loopers per sweep is a treatable level. Based on my field observations I would treat in the neighborhood of four loopers per sweep.

Stink bugs are increasing in beans and will likely continue to do so in the days ahead. Therefore, in many fields a stink bug material (pyrethroid) or acephate (Orthene) may need to be added as we treat for loopers with the recommended insecticides of Tracer (Blackhawk), Intrepid, Steward or Belt.

One or more soybean fields in Southwest Alabama are infested with the garden fleahopper at damaging levels. This is a first for this insect on soybeans. They occurred on peanuts in that area a couple of weeks ago.

Some peanut fields are also infested with this mix of caterpillar pests. In this mix we are also finding fall armyworms, southern armyworms, corn earworms, cutworms, yellow striped armyworms and immature burrowing bugs.

Both soybeans and peanuts need to be scouted weekly for the remainder of this season and future seasons. The old method of spraying an insecticide on soybeans or peanuts when fungicides are applied is really just a stab in the dark. The odds of this being good timing for insect control is somewhere between slim and none. With the price of beans we have to do a better job with insect control than automatic sprays based on the stage of the beans.

Most of our comments in the next week or so will be directed towards soybeans and peanuts.

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.

Insect and Weather Update for the week of July 9th 2012

The past 10 days have been characterized by heat, drought, scattered thunderstorms, aphids, and in some cases spider mite decisions. Some areas have received one or more rainfall events of 1 to 3 inches or more while others are still suffering extreme drought. Some of these storms have brought high winds, downed trees, demolished buildings and hail.

Insects have been rather quiet overall. Many field men have made aphid treatment decisions with significant acres treated. In at least one incidence, both aphids and mites were at treatment levels. Other more sporadic fields have needed adult tarnished plant bug controls. In the majority of cases the plant bug population has now shifted to immatures. In these cases field men need to switch from sweep nets to drop cloths to quantify these immature plant bugs. Two or three immatures per drop could be considered a threshold level requiring treatments, especially if “dirty” blooms are present. Pinhead square retention is no longer the best way to look for plant bug damage since they spend more time down in the canopy feeding on larger squares (which later become dirty blooms).

I have not had any calls yet, but field men in the southern areas of the state need to pay attention to stink bugs since our oldest fields are now at week three, four or more of bloom. Weeks three through six of bloom is when stink bugs are most damaging. A good threshold for treatment during this period is 10-15% internal damage to quarter diameter (still soft) 10-12 day old bolls. Look for brown areas near the seed  and warts on the inside boll wall where stink bugs have penetrated in search of a protection source in the form of developing seed. If the population of stink bugs is primarily the southern green species then we have choices of both pyrethroid and phosphates. However, as most likely the case, the population may be predominately brown stink bugs. Here we would need a phosphate such as Bidrin or either a high rate of bifenthrin and get decent suppression.

Reports were just received of an increase of small larvae on peanuts in south-central Alabama. My guess would be that they are tobacco budworms. By July 15, newly hatched larvae will more likely be corn earworms.

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.

Weather Conditions and Pest Control

First we will give an overview of weather conditions, especially since this may be impacting some of our insect and pest control decisions in the coming days. After a good moisture and rainfall pattern of about 10-14 days ago, our crops have reached a hot-drought stressed condition at present. The situation is worse in the northern area of the state where less rainfall fell during the last thunderstorm period. I saw corn wilted bad in the Tennessee Valley on Tuesday (June 19).

This droughty situation could well impact spray decisions with pests such as aphids and s. mites in the immediate days ahead. Aphids are building state wide and drought stress plants are where I am more suggestive for chemical controls instead of waiting for the natural fungus.

Tarnished Plant Bug adults are also being reported from some fields from the Tennessee line in the north to the Florida line in the south. Square retention is dropping, especially in fields in South Alabama that are a couple of weeks into bloom – these would be early-mid April planted cotton. Also in these some fields, adult brown stink bugs are being reported. We know from past years what stink bugs do to small thumb sized bolls when no larger ones are present.

If present in cotton, stink bugs will feed on small bolls to develop. Knowing this impacts the chemical that we may want to choose for TPB control. It needs to be a product that also controls or highly suppresses Brown Stink Bugs. The best options here would be Bidrin or a high rate of bifenthrin. Aphids in the picture would further complicate the chemical selected. Of the neonic type products, Centric might be the best choice for Tarnished Plant Bug adults, Brown Stink Bugs and aphids.

Three-Cornered Alfalfa Hopper damage is still evident in cotton, in reddish stunted plants that have a girdled and swollen area around the main stem. However, this damage is old now and most plants are too tough for main stem girdling by the Three-Cornered Alfalfa Hopper.

The biggest insect news of the week in Alabama was the finding of the Kudzu bug in soybeans in Cherokee County, Alabama on June 21. The Kudzu bug had been found in about 25 counties on Kudzu but this was the first find on soybeans. Alabama growers will want to lean heavily on recent research conducted in Georgia, South Carolina, and North Carolina on this new envasive pest. We need to beef up our scouting on soybeans for this pest – especially the immature stage.

Current Insects in Cotton at Economic Levels

Today I would like to discuss three insects that are occurring in cotton at economic levels in certain fields. Two of these insects are actually impacting other crops, particularly soybeans and peanuts, as well.

Adult tarnished plant bugs (TPB’s) are being reported at moderate to high levels in some fields statewide. More findings are reported each day and there are likely many fields where they are present but have not been observed yet. At this point, no one has reported high pinhead square loss. This square loss is what we like to base our treatment decisions on. However, based on past experiences, once the adult TPB’s are present it is just a matter of time until some level of square loss is detected. These are all migratory adults that have moved into cotton from wild hosts. They will feed on pinhead squares, which cause abortion, and also deposit eggs in the plant stems. These eggs will hatch in two plus weeks into an immature field generation. The longer the period that adults are allowed to roam in fields, the longer the period of hatching immatures will be in coming weeks. Knowing this, growers can make their own decision as to when controls should be applied.

The second insect I will mention is the tobacco budworm (TBW). An extended flight of budworms has been ongoing in various areas for about two weeks already. This is of no significance to 98% of the states acreage that is planted to Bollgard II or WideStrike varieties. However, this makes a tricky situation in conventional cotton that may need plant bug sprays during this TBW period. This TBW flight is also impacting later planted peanuts that have a limited amount of vegetative growth. Budworm moths seem to be attracted to peanuts with a vegetative width of 3-4 inches. Earlier peanuts that have six of more inch vegetative width do not appear to have as many budworms present. We collected about 250 quarter inch budworms yesterday at Headland, Alabama on about 600 row feet. This was not what I would consider an economic or treatable level. However, up to four budworms per row foot have been reported in some fields and controls, with the newer chemistry, have been applied.

The third insect that is causing widespread concern in cotton at present is the three-cornered alfalfa hopper (3CAH). Numerous fields in the Tennessee Valley area of northern Alabama have had damaging levels of 3CAH reported. This problem has extended as far south as Talladega County. Treatments have been applied. Soybeans are also experiencing a problem with this insect, even more so than cotton, and over a much larger geographical area. 3CAH damage is caused by the girdling of the main stem of both cotton and soybeans by both the adult and immature 3CAH. No good thresholds exist from Alabama research. Usually this problem and damage is greater on field borders but consultants have reported damage field wide in both cotton and soybeans. Treatment thresholds are difficult to develop for 3CAH, just as they are for grasshoppers. Treatments sometimes have to be made based on the risk that certain species present, and not the level of damage observed. Sweep nets are very effective in documenting the number of 3CAH per row foot.

Tarnished Plant Bugs Found

A significant level of adult tarnished plant bugs was found this morning (June 4^th) in nine true leaf cotton in Autauga County Alabama. Levels of up to five adults per 100 plants were reported. No pin head square loss was observed but it is likely just a matter of time until damage is observed. Controls are planned.

In addition to these tarnished plant bugs, eggs, most likely tobacco budworms, were also reported.

Announcing Alabama Scouting Schools

Announcement: Alabama Cotton Scouting Shortcourses Meeting Sites and Dates

• June 12^th (Tuesday) 2012; Autaugaville, Alabama- County Agricultural Center
• June 13^th (Wednesday) 2012; Headland, Alabama- Wiregrass Research Center
• June 19^th (Tuesday) 2012; Belle Mina, Alabama- Tennessee Valley Research Center

All meetings begin at 8:30 AM

Contact Person: Dr. Tim Reed (256-627-3450) or Dr. Ron Smith (334-332-9501)

Note: Dr. Austin Hagan will discuss cotton diseases at the Autaugaville and Headland sites. Dr. Tim Reed will cover soybean insects at all three sites.

Following are thirteen questions that represent the type of information that will be discussed.

1.      Why are grasshoppers easier to control in March/early April than May?

2.      If a foliar is needed for thrips suppression, when is the ideal stage of cotton to apply it?

3.      If you see damage to cotyledon stage cotton (no till) planted behind corn residue, what is the most likely culprit: snails, slugs, or pill bugs?

4.      What is the best method to determine when plant bug controls are needed in pre-bloom cotton?

5.      How would you measure the number of tarnished plant bugs in post bloom cotton?

6.      You are at week four or five of bloom, what would be the threshold for stink bugs?

7.      Under what conditions (situation) would a phosphate insecticide give better control of stink bugs than a pyrethroid?

8.      What new thrips insecticide entered the market this season and does not flare aphids or spider mites?

9.      Suppose you find high numbers of fall armyworms feeding on grass in your cotton field border- should you prepare to spray the cotton?

10.   How old does a green boll need to be to be safe from stink bug damage?

11.   Under what conditions would aphids be more of an economic pest or problem?

12.   At what stage is cotton normally beyond thrips injury?

13.   How long should you wait to evaluate control behind a stink bug spray?

Fine Tuning Cotton Insect Management for 2012

I. Thrips Control

1. Need for foliar overspray
• Influenced by planting date primarily but also to lesser degree by night temperature and overall growing conditions
• Seed treatments planted from early April to about May 10th would benefit from foliar overspray
• Seed treatments give 21 day thrips suppression as opposed to 28+ days with in-furrow granules
• What you see with thrips injury above ground is reflective also of underground root conditions and growth

2. Timing of overspray
• Most beneficial when most of plants have 1st true leaf about the size of a small finger nail
• Cotton with 4 or more true leaves usually does not benefit from overspray
3. Multi state research in 2011 indicated that acephate (Orthene or generics) was equal to or superior to all other choices
• Certain pyrethroids were a weak choice
• Bidrin is effective but I would suggest saving for stink bug control. New label limits total use of Bidrin in one season to 1.2 lbs active.
• New products tested: Benevia (Dupont) and Radiant ( Dow). Both looked very effective but not certain about registration date and cost.

II. Nematode Management

1. Rotation- peanuts, grain sorghum, corn
2. Variety selection- PHY367WRF has root knot tolerance
3. In-furrow granules
• Loss of Temik
• Meymik registered on December 22, 2011 (production and supply for 2012 uncertain)
4. Seed treatments
• Suggest to use on lower risk fields
• In high nematode risk fields would be like using a Band-Aid when a tourniquet is needed
5. Fumigate (Telone)
• Consider site specific nematicide placement (Precision Ag)
• Nematodes usually not evenly distributed across field
6. Deep tillage- grew cotton over 100 years without nematodes being a limiting factor- only since reduced tillage have they become a major problem

III. Plant Bugs

1. Movement from wild host into cotton influenced by climate
• Hot/dry results in high peak but short in time
• Wet/cool spring results in low movement over longer period
2. Most effective insecticides
• Acephate (Orthene, generics)- can flare spider mites
• Bidrin- good but only labeled for post bloom period
• Centric- effective but hard on beneficials and fire ants
• Pyrethroids- can flare spider mites
• Diamond- very effective on immature stage post bloom, especially when tank mixed with one of the above
• Intruder, Carbine, imidacloprid (Trimax), Belay, Vydate- less effective than others with one application

IV. Plant Bugs + Aphids (July)

1. Intruder, Carbine, imidacloprid (Trimax, etc.), Centric
2. Diamond may be combined with the above

V. Mid Season Worm Overspray

1. May be more important with Phytogen varieties
2. Timing could be mid July to early August depending on your north to south location
3. Pyrethroids are a good fit here
4. If brown stink bugs are also present, may want to select bifenthrin or Bidrin XPII (combination of Bidrin + Bifenthrin) or use highest labeled rate of other pyrethroids
5. 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

VI. Fall Armyworms

1. 2010 and 2011 seasons have produced widespread outbreaks of the “grass” or “rice” strain of the FAW
2. This strain primarily attacks pastures, hay, grasses and peanuts and are easy to control with most insecticides, including pyrethroids
3. They do not prefer to feed on cotton or corn

VII. Stink Bugs

1. Some level of scouting needed for most economical control
• May need 0-4 sprays ($6-9 each considering application)
• Could pay for a field scout with savings or reduced damage from stink bugs alone
2. Most effective scouting is to examine 10-12 day old bolls for internal injury
3. Use “dynamic” or sliding threshold which considers the number of bolls at risk at a given week of bloom

4. Possible Reasons for Low Stink Bug Pressure in 2011
• Winter temperatures (colder than recent winters)
• Southern green stink bug is very sensitive to cold weather
• Impact of hot, dry spring on wild host/corn—may have reduced numbers of brown stink bug species
5.  New Stink Bugs
• Brown Marmorated Stink Bug
• Kudzu Bug (soybeans)
• Red-Banded Stink Bug (soybeans)  



Brown Marmorated Stink Bug



Red Banded Stink Bug

 

Kudzu Bug

 

VIII. New Products and Technology

1. Sulfoxaflor (Transform)- Dow
• Effective on plant bugs and aphids
2. Beseige (combination of Karate + Coragen)
• Effective on broad spectrum of caterpillars (loopers, fall armyworms), plus would have green stink bug activity
3. Endigo (combination of Karate + Centric)
• Effective on certain caterpillars, plant bugs, aphids and green stink bugs
4. Belay- in market place for past two seasons for plant bug/stink bug control
• Still need more University research to get a good handle on effectiveness
5. Prevathon (Dupont)
• One of most active caterpillar insecticides ever developed
• Excellent residual, depending on rate
• Very rainfast
• Should be targeted at egg stage or small larvae
6. Bayer Twin-Link
• Contains multiple Bt genes
• Performs somewhere between WideStrike and Bollgard II for caterpillar control
7. Bollgard III
• Under development
• Third gene is not a Bt so it has multiple modes of action for worms
• Reduces escapes over Bollgard II and will provide long term resistance management for the genetic technology
8. Poncho/Votivo Seed Treatment
• Insecticide + biological nematicide
• Looked at it in one trial on cotton and could see growth response and earliness, even under low nematode pressure



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.

Tarnished plant bug, aphid, tobacco budworm and fall armyworm numbers on the increase

Tarnished plant bug adults were found in numerous fields in western Alabama (Lamar County) on Friday (July 8). Pin head square loss was minimal (less than 5%) and very few immature plant bugs were found. This would indicate that adults had moved into cotton fairly recently. However, this is a situation where damage could increase rapidly if controls are not applied.

Several calls were received late last week about increasing aphid populations in some fields. Aphids are late developing this season, which means they also could be late crashing from the fungal disease. This being the case, the peak aphid stress will come during the early boll set window. Growers may find it best to apply aphid controls and prevent plant stress at this stage of maturity.

Heavy tobacco budworm damage has been occurring on sentinel plots of conventional cotton in SW Georgia for the past week. Growers with Bollgard II and Widestrike can sleep well at night knowing that their investment in technology is working to near perfection.

The “grass” strain of the fall armyworm is now damaging pastures and hay crops in several south Alabama counties. This strain will also feed on peanut foliage but will not feed on cotton.

Tarnished Plant Bugs

High numbers of adult tarnished plant bugs have been reported by two consultants in the Talladega county area this week. In both cases the fieldmen found the plant bugs before square retention began dropping. Numbers as high as 21 adults per 100 row feet were recorded. This is far in excess of what I would consider threshold. Some might question if they should wait until square retention drops before applying controls. I would suggest for controls to be applied immediately since this generation of bugs will not only feed, causing square loss, in the next week—they will also deposit eggs in the plant tissue that will result in a July in-field generation.


A few growers have expressed concern about conserving beneficials but one advantage of having Bollgard II and WideStrike genetics is that you can react to plant bugs when they reach damaging levels. We do not have an insecticide that will kill tarnished plant bugs and conserve beneficials. Any chemical choice that is selective on beneficials would also be selective on plant bugs.

Tarnished Plant Bugs Threatening Cotton Yields

Tim Reed, Extension Entomologist

June 21, 2011

Control measures for tarnished plant bugs (TPB’s) in the oldest cotton fields in north Alabama began two weeks ago and initial applications continue to be applied to later planted fields. Consultants report TPB pressure to be higher than normal than at this time last year and there is concern that some fields, especially older fields may require two TPB treatments. The cooler, wetter weather we are having this week in parts of Alabama will be favorable to TPB’s. The longer TPB treatments are postponed the more eggs are deposited by adult TPB’s which result in higher numbers of immature TPB’s present in late June and July. One consultant reports that TPB’s can presently be collected in a sweep net at any time of the day in north Alabama cotton fields but they tend to be more abundant on field edges. Some cotton fields in Montgomery county this week are also suffering 20% (Bt cotton threshold) or better pin head square loss due primarily to TPB damage and there could be control measures initiated in this central Alabama county this week. TPB’s are a much more serious pest for conventional cotton producers than for Bt cotton growers since all available chemicals that control adult plant bugs also significantly reduce beneficial insects/spiders. This increases the chances of a severe tobacco budworm infestation in the last half of June. Conventional cotton growers have a difficult time deciding on whether or not to spray for adult plant bugs in mid-June when they know it will be expensive to “fight” worms. Dry weather makes the decision even more difficult. Mississippi entomologists are reporting higher than normal numbers of tobacco budworm moths being collected in pheromone traps and budworm moths are now depositing low numbers of eggs on cotton in Montgomery county. Another concern for all cotton producers is the fear of spider mite populations increasing after TPB applications. Spider mites tend to appear in the same areas each year. Thus far a few north Alabama cotton fields have been treated with bifenthrin to help slow spider mites. Serious spider mite problems will require more expensive chemistry and consultants hope disease will take out the spider mites before more costly chemicals are required.

Tarnished Plant Bugs Reported in Central Alabama

Three fieldmen from central Alabama (Montgomery, Macon and Lee Coutnies) reported significant movement of adult tarnished plant bugs into cotton this week. Damage, in the form of pinhead square loss, was evident in all three locations. Square retention was below 70% in several fields. This square loss will likely become greater if controls are not applied since the plant bugs are relatively young and have several more days to do damage. Bidrin, Orthene (or generics), or Centric would provide the highest level of control. Pyrethroids would also provide an acceptable level of control. We need to set a high percent of early fruit in fields that have received moisture in the past few days.

Drought Conditions Continue

Despite a few scattered thunderstorms, the drought conditions continue to dominate the row crop situation in much of Alabama. We have cotton that ranges from about 13-15 nodes (planted mid April) to other fields lacking moisture for seed germination. The oldest cotton is about knee high with squares from nodes 6 through 13-15. At this point, potential plant bug damage does not appear to be high. Roadsides and field borders dried down before cotton was old enough to provide food and shade in most fields. Excessive heat during the past 30 days has likely reduced plant bug populations on wild hosts.

Thrips numbers have been low for several weeks following about 4 weeks of high pressure from late April to mid May. The most prominent insects of the past few weeks have been false chinch bugs and white margined burrower bugs.

Most fields are in the stage between being susceptible to thrips and being susceptible to plant bug injury.