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Enhance Economic Opportunities for Agricultural Producers
Managing Lygus Bug in Cotton
Impact Nugget
In response to Arizona Cooperative Extension’s IPM program for
managing Lygus bug, more than 50 percent of the region’s cotton
growers have changed their chemical tactics against Lygus by switching
to single compounds used strategically and at appropriate rates as part
of an IPM system. This has resulted in a 66 percent reduction in the
number of acres receiving spray mixtures for Lygus, while increasing
effective rates by about 20 percent. Education efforts across the border
in Mexicali, Mexico have resulted in the majority of cotton growers
there adopting threshold and other IPM guidelines for Lygus management.
Issue
Integrated pest management (IPM) plans must be flexible enough to accommodate
different insect pest pressures from year to year. After years of lesser
recognition as a cotton pest, Lygus bugs have become the number one
pest of cotton since 1998. Among growers, typical control measures for
Lygus have involved tank mixing combinations of broad-spectrum insecticides
in the unfounded hope that this practice will give more control over
the pest.
What has been done?
The UA College of Agriculture and Life Sciences has developed an integrated
pest management program (IPM) for Lygus in cotton aimed at reducing
insecticide use through adequate field sampling, adherence to threshold
guidelines, and using the right compound for the job. Above all, it
emphasizes avoiding pest pressures wherever possible. These measures
are being incorporated into the larger cotton pest management program,
and focus on reducing spray applications from mixed broad-spectrum insecticides
to more selective, targeted single insecticide applications. One key
to the success of the program has been the accurate identification of
single spray compounds that perform consistently against Lygus and knowing
precisely when to use them. The education component of this program
has assisted growers in implementing this strategy during the last eight
seasons.
Through dedicated screening trials conducted each year, three new reduced-risk
technologies have been identified which may provide selective control
of Lygus bugs. This research conducted in collaboration with agrochemical
companies should lead to new registrations that will aid growers in
transition away from broadly-toxic insecticides for Lygus control and
facilitate IPM programs that seek to conserve natural enemies useful
in pest control.
Because Lygus bugs survive and multiply on many different hosts, a
collaborative project was conducted with growers in a large agricultural
area and with the Arizona Cotton Research and Protection Council to
determine the factors that contribute to the abundance of Lygus populations.
These studies, part of a larger cross-commodity program in the UA College
of Agriculture and Life Sciences, identified key sources of Lygus populations
and provided guidelines on planting patterns and distances that should
help avoid Lygus problems in the future.
Through use of spatially-explicit information in a geographical information
system (GIS), educators can now advise growers that sensitive cotton
crops will be negatively affected by other Lygus sources, such as seed
alfalfa, grown within 1.5 km of their crops. Further, researchers found
that clustering many cotton fields together provided “safety in
numbers” by helping to dilute the negative impact of Lygus migrating
from non-cotton sources. This information helps pest managers address
decades-old nagging questions about Lygus movement and will help guide
them in the introduction, placement and cultivation of other crops on
which Lygus reproduce.
Impact
In response to this IPM program, more than 50 percent of the region’s
cotton growers have changed their chemical tactics against Lygus by
switching to single compounds used strategically and at appropriate
rates as part of an IPM system. This has resulted in a 66 percent reduction
in the number of acres receiving spray mixtures for Lygus, while increasing
effective rates by about 20 percent. In 1999, growers applied the fewest
number of sprays statewide against Lygus in cotton since 1993, thus
reducing their costs per acre while protecting the environment. Education
efforts across the border in Mexicali, Mexico have resulted in the majority
of cotton growers there adopting threshold and other IPM guidelines
for Lygus management.
Arizona extension entomologists have been able to teach and demonstrate
to growers that single compounds are as effective or even more effective
than broad-spectrum combination sprays, and that this practice helps
reduce the risk of resistance in Lygus and other insects while minimizing
negative impacts on beneficial insects. More growers are now aware of
the specific midseason timing (thresholds) required for the control
of Lygus and for providing maximum economic return. They are also aware
of new information on when precisely to discontinue sprays against this
pest late in the season.
Some growers reported immediate savings of $25 per acre by curtailing
sprays earlier than they would have done otherwise, because research
showed that they were not cost-effective. The success of this program
has led for the first time to efforts to control Lygus across multiple
crops (Lygus are highly mobile and feed on several crops in addition
to cotton.) Through community-wide cooperation with growers in a large
agricultural region, researchers were able to collect enough information
about distributions of Lygus across multiple hosts to formulate concrete
recommendations for planting patterns and distances from sources.
Funding
Hatch Act
Smith-Lever 3(d) (e.g., IPM)
Western Region IPM; Pest Management Alternatives Program
UA program enhancement (CES); UA IPM and CROP programs
Cotton Incorporated, Arizona Cotton Growers Association
Agrochemical companies), NSF's Center for Integrated Pest Management
ADA’s Specialty Crop Program, Arizona Cotton Research & Protection
Council
Contact
Peter Ellsworth, IPM specialist
Maricopa Agricultural Center 37860 W. Smith-Enke Road
Maricopa, AZ 85239-3010
Tel: (520) 568-2273, FAX: (520) 568-2556
Email: peterell@ag.arizona.edu
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