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.
