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.
