Thursday, February 4, 2021

Looking Back as a Career Winds Down: 50 Years of Cotton IPM in Alabama (1971-2021)


I began my career as an Extension entomologist at Auburn University on April 24, 1972. To put that into perspective – Richard Nixon was president and the Vietnam War was still ongoing. I have worked under the direction of eight Alabama Cooperative Extension Directors and numerous Deans of the Ag School/Experiment Station.

It has been quite a journey to have been a part of the most evolutionary period ever in cotton insects. I began my career when boll weevils were the key and dominant cotton insect in Alabama and as part of the new USDA-Extension cotton IPM educational initiative. Each cotton producing state received new federal funding to add one additional cotton entomologist. Two states, North Carolina and Arizona, added an additional entomologist a year earlier, in 1971. In 1976, this increased educational program had proven so successful that additional funding was provided that enabled the Alabama Cooperative Extension Service to add two additional area entomologists (Decatur and Selma) and four multi-county IPM agents (three in the Tennessee Valley, where a high percentage of the cotton acreage was at that time, and one in central Alabama). The special funding for this program effort continued for more than 30 years. The goal of this new program was to increase the awareness of a management approach to controlling cotton pests. 

The Extension cotton scouting program and use of economic thresholds, which forms the basis of a management approach, was initiated by Drs. Walter Grimes and Roy Ledbetter with the aid of Mr. Frank McQueen (survey entomologist) in the late 1950’s and early 1960’s. During the early to mid 1970’s our primary cotton insecticide tool was the organophosphate class of chemistry. The organophosphates, such as methyl parathion and Guthion, were characterized by fast acting activity but short residual. In addition, most chemicals in this class had acute human and mammalian toxicity. The phosphate chemistry had excellent activity on the boll weevil but brought on resistance in the tobacco budworm and secondary pests such as spider mites and whiteflies. The heavy use of phosphate insecticides also caused major problems with delayed maturity of the crop. This problem with delayed maturity was so pronounced that a special session was added to the Beltwide Cotton Research and Control Conference in January of 1976. Another type of insect control tool, that many of today’s growers do not remember, was available during the 1972-1989 window. This tool was the ovicide (worm egg only) chemical chlordimeform, sold as Galecron and Fundal. This chemical impacted cotton IPM scouting programs by creating a need to change to twice per week field monitoring (scouting). The life stage of a bollworm or tobacco budworm egg was only three days, so the increased egg counts had to be detected and targeted with an ovicide within a three day window when egg numbers peaked.

In 1976, the pyrethroid class of chemistry became available, first under an EPA issued emergency use permit (EUP). In 1978, pyrethroid insecticides received full but conditional registration and became the major player in cotton insect control for the next decade. For a few years, pyrethroids were highly effective on most all cotton insects. Insect losses were very low, yields reached a new higher plateau, and maturity issues disappeared. Due to extended residual from the pyrethroid insecticides (Ambush, Pounce, and Pydrin) application intervals for the boll weevil could be extended from 5 to 7 days. However, during the decade of the 1980’s, depending on the area of the Cotton Belt, tobacco budworms became resistant to the pyrethroid class of chemistry.

It was during this time period that the final plan to eradicate the boll weevil was being developed. This program had been under development for more than a decade. One of the big driving forces to eradicate the weevil was the possibility that boll weevils might develop resistance to the organophosphate class of chemistry. This possibility would have wrecked the cotton industry in the U.S. Pyrethroids had activity on the weevil but were not as effective as the phosphates and were initially significantly more expensive. The boll weevil never developed resistance to the phosphates, in fact, the phosphate insecticide malathion was the primary insecticide used for eradication.

In the Fall of 1986, the organized boll weevil eradication initiative reached Alabama. This program was first started in northeastern N.C. (Chowan Co.) a few years earlier. Twenty-one counties in southern Alabama were included in the first eradication zone. During the following 7 years the program was expanded throughout the remainder of the state (central AL – 1992, NE AL – 1993, and TN Valley – 1994). By the summer of 1995 no economic losses to the boll weevil could be found anywhere in the state.

During the active eradication program period (1986-1995), insecticide resistant tobacco budworms and impossible to control beet armyworms caused yield losses beyond anything ever observed or previously recorded. During one season, yield losses to beet armyworms alone were estimated to be about $40 million across the state. Pirate, a new highly effective chemistry that was under development by American Cyanamid, was requested for emergency use from the EPA multiple years. However, this request was denied until August of 1995, which proved to be too late to help with the beet armyworm outbreak that had been ongoing since 1987. At the end of the 1995 season the outlook for the future of cotton production in Alabama was bleak.

Fortunately, genetically altered Bt (Bollgard) cotton varieties, which had been under development and evaluated in select fields for the previous four seasons, became available to growers. This new technology was readily adopted by Alabama growers and 77% of the 1996 acreage was planted to Monsanto Bollgard varieties. This rapid adoption was primarily in self-defense following the heavy losses to worms the previous years. However, planting this new technology brought with it rules and regulations never experienced before by growers. Word was spoken that growers would never have to treat for worms again. This proved to be incorrect when in late July 1996 news of bollworm escapes in the Brazos River area of central Texas spread across the Cotton Belt. It was only about one week later when this escape bollworm and fall armyworm problem was observed in Baldwin Co., Alabama. Some growers wanted to give up on this new technology immediately. However, over the following years entomologists and growers learned more about what to expect form Bollgard cotton varieties and how to manage these escape bollworms, which could be controlled with a minimum of well-timed pyrethroid sprays. The following 10 years proved to be good for growers with overall improved yields and minimal insect losses and control costs.

It was during this low spray environment that the bug complex became more damaging to yields. In north Alabama it was the tarnished plant bug that had to be monitored and managed more closely. In central and south Alabama, as well as the remainder of the Coastal Plains of the southeastern U.S., it was the stink bug that became the dominant economic insect of cotton. Entomologists in the Carolinas, where the weevil was first eradicated, had reported that stink bug damage increased. However, populations of the southern green stink bug in the southeastern U.S. caused even greater damage than did the green stink bug species in the Carolinas. It took several years for growers and fieldmen to realize how devastating the stink bug could really be.

By the time better stink bug management was adopted, the Bollgard technology, with one Bt gene, began to lose its effectiveness and escape bollworms were more widespread . Experts had warned that this phenomenon would happen since the single Bt gene was never 100% effective on the bollworm species, as it was on the tobacco budworm. Anticipating this, Monsanto had begun work on stacking a second gene. This second Bt gene entered the market in 2009 and reduced this escape bollworm problem by about 90%, followed by Bollgard III in 2018. WideStrike genes from DOW AgroSciences (Phytogen varieties) first became available in 2005 and were followed by the third gene (WideStrike3) in 2014.

Cotton insect control overall from 1996 to 2020 has been good with no boll weevils or tobacco budworms and minimal escape bollworms in the system. However, sucking pests such as thrips, aphids, whiteflies (silverleaf) and spider mites have required monitoring and management. In addition, due to reduced tillage trends, certain sporadic or new pests have had to be contended with. Some of these are grasshoppers, cutworms, snails, slugs, and early season spider mites. However overall, the past two decades have required careful monitoring and selective management and control skills, but insect losses and control costs have been historically low and have served to keep the cotton industry profitable in Alabama.

The evolution of cotton insect management is so great that fire ants are now considered as the number one beneficial insect against escape bollworms in our reduced tillage system. It is felt by several entomologists that fire ants are playing a big role in allowing Alabama growers to continue to plant two-gene varieties, primarily DP 1646, without the need for costly diamide chemistry (Prevathon and Beseige) oversprays. The diamide chemistry, developed by Dupont, is highly effective when applied timely on most worm species. What would have been a significant development, had it not been for the introduction of genetically modified genes back in 1996, was the introduction (1996-98) of spinosad (Tracer) chemistry by DOW AgroSciences. For the first time since the development of synthetic pesticides in the 1940’s, caterpillar pests could be controlled with this selective chemistry while lady beetles and other beneficial insects were not affected and remained in fields.

More recent years of cotton insect control have been dominated or characterized by the emergence of sucking pests, such as aphids, spider mites, thrips, and whiteflies (silverleaf), and the bug complex (plant bugs, stink bugs, and leaf-footed bugs). As we moved into this reduced foliar spray era following the elimination of the boll weevil and tobacco budworm, our chemical tools became more selective. Our new caterpillar insecticides do not control sucking pests or the bug complex and the sucking pest insecticides do not control the bug complex or escape bollworms. Insecticides targeted for the bug complex give limited control of sucking pests or escape caterpillars. Tank mixes of two or more insecticides are again often necessary. In the 1950’s and 60’s most insecticides were formulated as mixtures at the distribution level. Now, these mixtures are prepared on the farm as the sprayer is being loaded.

The future will likely continue to be dominated by our current conditions. New advances may be limited. Few new chemistries will be developed. Development cost of chemistry cannot be recouped from cotton usage alone, as was done in the earlier years. New chemistry developed today must find market share with all row crops along with vegetables, fruits, nuts, and other grain and food crops. New advances will likely come in the form of genetics. These advances take years of research and development and as many or more regulations as do chemicals. A thrips-lygus gene is nearing the marketplace in 2021. Based on research, this gene may prove most effective on thrips with moderate activity on plant bugs. It will not help on stink bugs, which are likely to continue to be the dominant economic insect in Alabama and the Coastal Plains of the southeastern U.S. Rather than advancing the discipline of row crop and cotton entomology, our future may be described as a “stay ahead of resistance” in the decades ahead. Resistance issues are present today in the following species: thrips, plant bugs, bollworms, spider mites, aphids, and possibly other species. The greatest challenge in entomology today is staying ahead of resistance and managing sporadic pests such as slugs, snails, cutworms, grasshoppers, three-cornered alfalfa hoppers, leaf-footed bugs, and others. Reduced tillage has been a great advancement; however, this practice has created numerous cracks that are being filled by sporadic pests that require the attention of entomologist and fieldmen advisors.

In summary, the past 48 years of cotton production and insect management have evolved in many, and in some instances unexpected, ways. Examples include:

·       The change from intense cultivation to reduced tillage and heavy dependence on herbicides.

·       The development of major resistance issues with weeds and numerous insect species.

·       The development of increased problems with nematodes and, potentially in the future, plant viruses.

·       A shift from boll weevils to the stink bug complex as the most economic insect.

·       The change from phosphate chemistry to the pyrethroids and now the diamide chemistry.

·       The change from 5 day insecticide application schedules for boll weevils to 2 to 4 seasonal foliar sprays.

·       The escalation from nominal seed cost to very expensive seed and trait costs.

·       For most of the past 50 years, growers were using granular insecticides (Disyston, Temik or Thimet) at planting for early season insect control. In more recent years seed treatments, with neonicotinoid class chemistry, followed by foliar sprays were the standard practice for early season pests.

·       The change from moderate expenses per acre spread across the season to high, front-end budget inputs.

·       A shift from a few secondary pests to numerous new sporadic pests.

·       The change from Extension ag agents in every county to a regional agent with responsibilities spread over as many as 15 counties.

·       Early in my career, most Extension specialists had 100% Extension appointments and were not in academic departments at Auburn University. Most all of their research during those years was in the form of on-farm demonstrations. Now most all Extension specialists have split appointments (ex. 75% Extension, 25% research) and have professorial rank in our academic departments. These Extension specialists are conducting a high percentage of applied research on University research farms.

·       The shift from primary information sources of Extension agents/specialists and insecticide distributor salesmen to private consultants and well-trained commercial agrifieldmen.

·       The change from print media to electronic tools.

Entomologists who have been a part of the Alabama cotton pest management team over the past 48 years are: Roy Ledbetter, Frank McQueen, Ron Smith, Richard Davis, Glenn Worley, Barry Freeman, Tim Reed and Aaron Cato (post-doc). On April 1, 2020 Dr. Scott Graham assumed lead responsibility for this program. Dr. Graham is a native of Mississippi and has degrees working under prominent cotton entomologists (M.S. Mississippi State, Ph.D. University of Tennessee). Therefore, the program has great leadership for the future.

What an evolution and what a ride for an Extension entomologist over the past five decades. Always a challenge, always an additional idea on how to educate or have a more positive impact on cotton pest management. Job never complete nor finished, but most rewarding job in the world. Spent a career in trying to help my friends manage their insects. Knees are worn out but the mind is still going. Desire to be involved for a few more years in some capacity. I will end with a thought and a quote from one of my all-time favorite books, “Cotton is the greatest crop heaven ever gave to a country,” Red Hills and Cotton – An Upcountry Memory by Ben Robertson, 1940.