IPM Newsletter
An Integrated Pest Management (IPM) program integrates
control tactics including cultural practices, variety selection,
biological control and insecticides to manage insect pest
populations so that economic damage and harmful environmental
side effects are minimized. Insecticides should only
be used on an as-needed basis; therefore, insect scouting
must be conducted regularly throughout the season to determine
if an insecticide application is warranted.
Scouting/Monitoring:
Insect populations vary from year to year and field to
field during the growing season. All fields should be
monitored for both insect pests and beneficial populations
at least weekly during the season, preferably twice
weekly after blooming has begun. In areas of high
insect pressure or increasing populations, twice-a-week
scouting is recommended. Monitoring plant growth and
development is an important aspect of crop management,
maximizing yield potential and managing insects.
Two basic components of decision making in IPM
are the economic injury level (EIL) and the economic
threshold (ET). The EIL is defined as the lowest pest
population density that will cause economic damage.
The EIL is a pre-determined number that will justify the
cost of treatment. The ET is defined as the pest population
level at which control should be initiated to keep the
pest population from reaching economically damaging
numbers. Economic thresholds have been established for specific
insect pests. Multiple pest thresholds are not well established.
Therefore, it is important to monitor the plant for fruit loss
and retention levels to evaluate treatment thresholds, involving
either single or multiple pests. When losses from multiple
pests are occurring, fixed individual pest thresholds may become
dynamic or change. Decisions to apply controls should
be based on thorough scouting and identification of pests,
the cost of insecticide, the price of cotton, yield potential and
fruit-retention goals. The economic value of each fruiting
form changes on each fruiting branch (node); therefore, it is
important to know how this value is distributed on the plant.
The value and placement of fruit being protected should be
considered when making treatment decisions. Monitor fruit
retention levels weekly, along with insects. Scheduled insecticide
sprays should be avoided. Unnecessary applications of
insecticide are not cost effective. Applications of insecticides
on an as-needed basis will preserve beneficial insects, reducing
the likelihood of secondary pest outbreaks.
Certain production practices can have a significant impact
on insect pest infestations. Some practices may increase the
risk of insect attack and should be avoided, while others
may have some level of control value. A production practice
that has a negative impact on insect pests is desirable and is
termed a cultural control. Some common cultural control
practices include:
-
Fall Stalk Destruction:
Destruction of cotton stalks as soon as possible
following harvest reduces the food supply for boll
weevils, thereby reducing the size of the overwintering
population.
- Pre-plant Vegetation Management:
Destruction of weeds and/or cover crops by tillage or
herbicide three or more weeks prior to planting will
reduce the risk of cutworm infestations and some
other pests.
- Field Border Maintenance:
Plant bugs often build up on flowering plants
surrounding cotton fields and move into fields when
these preferred hosts dry up or are destroyed. Timely
mowing of such vegetation can aid in reducing
available hosts for plant bugs.
- Managing for Earliness:
Early crop maturity decreases the period of crop
susceptibility to yield loss by insects, reduces insect
control costs and lowers selection pressure for
resistance development to insecticides.
Insecticide Resistance
Management of tobacco budworm in non-Bt cotton varieties
has become more difficult in Tennessee due to the
development of pyrethroid-resistant populations. Historically,
budworm populations have been higher in the
southern part of the state, but high populations can also
occur in other areas. In response to tobacco budworm
resistance, and the potential for resistance in bollworm
and tarnished plant bug populations, a resistance management
plan will continue to be recommended.
The goal of the Insecticide Resistance Management Plan is
to improve the potential of maintaining effective full-season
control of tobacco budworm, bollworm and tarnished plant
bug by the use of different classes of chemistry in a logical
sequence throughout the season, without placing excessive
reliance on any single class of chemistry.
In general, levels of resistance are lowest during the early
part of the growing season but increase sharply following
repeated exposure to a single class of chemistry. Therefore,
repeated use of a single class of chemistry may no
longer provide effective control. As a result, there is a
potential risk of sustaining economic losses. Following a
resistance management plan is a recommended method
to reduce the risk.
Because cotton insect pest management is dynamic,
these guidelines cannot address all situations. Therefore,
these recommendations are not intended to limit the
professional judgment of qualified individuals. However,
the maximum benefit of a resistance management
strategy can only be realized if all producers in a
wide geographic area participate.
Selection of insecticides should be based on insect pests
present in the field, stage of crop development, effects
on non-target organisms and the risk of contributing to
resistance problems in subsequent generations.
Insecticide selection for bollworm and tobacco budworm
control should be made after determining the population
mix and size of the infestation within a community, farm
or field. When dealing with resistance, this determination
can mean a control success or failure. Use all available
information and techniques including scouting reports,
pheromone trap catches, moth flushing counts and identification
of “worms.”
For more information concerning cotton pest control, please visit: PB1768-Cotton in PDF format
Other IPM Programs within Tennessee
Cotton IPM
Corn
School IPM
Urban IPM / Fire Ants
For more information concerning Integrated Pest Management Programs, contact:
Dr. Scott Stewart
West Tennessee Research and Education Center
605 Airways Blvd.
Jackson, TN 38301
Phone = (731) 425-4709
email =
sdstewart@utk.edu