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.

Highlights of 2011 Research Projects

A multiyear-multistate (Southeastern U.S.) thrips research project, funded by Cotton Incorporated, was initiated in 2011. Evaluations were made with the following variables:

1. Base fertilizer only versus Base fertilizer + Starter
2. Fungicide only versus Seed Treatment + Fungicide
3. No foliar sprays versus Foliar sprays at the first or second true leaf stage
Both dryland and irrigated sites were conducted.

Observations from the first year of the study in Alabama were as follows:

1. The starter fertilizer did not benefit thrips control, especially on dryland sites.
2. If planting prior to May 15, some form of seed treatment is a must for thrips control.
3. Under heavy thrips pressure, such as 2011, a seed treatment alone will not give adequate control, if planting prior to about May 10.
4. Foliar sprays for thrips control should be timed at the 1st or 2nd true leaf stage (when the leaf is the size of a small finger nail). Foliar sprays after the 4th true leaf are seldom necessary.
5. Effectiveness of several insecticides for thrips control.
-Acephate (Orthene or generics) was equal to, or superior to, all others evaluated. Certain pyrethroids did not give acceptable control. Two new chemicals (Benevia-Dupont) and (Radiant-Dow) gave good results at the rates tested. Labeling and their economics are uncertain at present.

Another project was conducted to define the role of fire ants in suppressing caterpillar damage in varieties with various insect traits. A small plot (8 rows x 45 feet) replicated study was conducted utilizing three varieties: DP174RF, PHY565WRF and DP1050B2RF in blocks with no fire ants versus normal fire ants. The trial was conducted in a reduced tillage system. An end of season worm damage boll count was made and the results are presented in the following visual.

The numbers on the left show the number of worm damaged bolls per 45 feet.


Impact of Fire Ants on Bollworm Damage in Alabama Cotton