IPM Goes Areawide
ARS' program manager for the areawide pest management effort,
entomologist Carrol Calkins, discusses the placement of codling moth pheromone
dispensers in a pear orchard with technician Brad Higbee (left) and grower Dale
Large-scale, areawide pest management project may presage things to come
as fruit growers back new approach to codling moth control.
"There's a real need for an integrated attack against insects,"
Biel says, "but as individual growers, we don't know how to do it. We need
to cooperate and explore strategies, including nonchemical alternatives."
Help is on the way.
"To aid in this challenge, the Agricultural Research Service has
implemented an areawide pest management initiative," says ARS national
program leader Robert M. Faust. "This is part of USDA's effort to place 75
percent of all U.S. acreage under some form of integrated pest management (IPM)
by the turn of the century."
Basically, IPM is a system that combines many crop pest control practices
with careful monitoring of both pests and their natural enemies.
The key goals of IPM are to minimize disruptive pesticide usage and conserve
natural enemies while producing an undamaged crop.
Critical to IPM is extensive knowledge of the timing of pest life cycles;
methods to estimate damage thresholds, when remedial action must be taken; and
availability of selective treatments.
The first areawide program to be funded will help Biele and other fruit
growers, because it is aimed against the codling moth in the Pacific Northwest.
It incorporates IPM technologies that have had only limited practicein
individual orchardsand applies them in contiguous orchards owned and
managed by several growers.
Pest control is a major imperative in fruit production. Commercial apple and
pear growers, for example, begin to lose money when insect damage exceeds just
1 percent of their crop.
In the Rogue Valley near Grants Pass, Oregon, a field worker
attaches pheromone dispensers in a pear orchard.
However, "Chemical sprays are not as effective as they once were for
controlling codling moths in our orchards," says John Biele, a fruit
grower in northern Washington. "We find it necessary to spray more and
more, because the moths keep building up their populations.
This program is being coordinated by the ARS Tree
Fruit Research Laboratory [Since publication, the name of this facility was
changed to the Yakima Agricultural
Research Laboratory.] at Yakima, Washington, along with Washington and
Oregon State Universities and the University of California at Berkeley.
While the main tactic for suppression will be mating disruption, other
tactics will include Bacillus thuringiensis (Bt) sprays and parasite and
sterile male codling moth releases over large areas.
Typically, IPM programs are conducted on individual orchards and are based
mainly on chemical sprays for control. In some successful programs, chemical
control has been expanded to larger areas and newer control strategies have
also been used.
One such project involved cotton growers in the southeastern United States
who were battling the destructive boll weevil.
Starting in 1978, there was a coordinated effort to apply chemicals to kill
weevils that were making cotton production unprofitable for some growers. Less
than 10 years later, the boll weevil was essentially wiped out in North and
here for table detailing the
Codling Moth Pilot Project.
Today, thanks to additional controls that include early plow-down of crop
residue, introduction of natural enemies such as fungi and predatory insects,
and use of bait traps, the insect is under control in parts of Florida,
Alabama, Mississippi, Texas, Arizona, and California. In some cases, pesticide
applications have been reduced from 12 a season to as few as 5 or 6.
An important lesson from this boll weevil control program is that success
depends on a concerted, coordinated effort by all growers within a region.
More recent IPM programs have promoted nonchemical methods as the basis for
pest control, with the use of pesticides a last resort.
"When farmers first planted apple trees in the Pacific Northwest about
95 years ago, they didn't need insecticides," says ARS entomologist Carrol
"But by the 1920's, codling moths had become established, and growers
were spraying trees once or twice a year. Now, some growers need to apply
insecticides for codling moth control up to six times a year, as insecticide
Calkins heads a project at the ARS Tree Fruit Research Laboratory in Yakima,
Washington, that is aimed at finding better ways to control insects in fruit
trees with less reliance on chemical pesticides.
Pheromone dispensers like this one attached to a pear tree
flood orchards with so much synthetic female codling moth scent that males find
it all but impossible to locate a mate.
But this source of the proverbial "worm in the apple" is
particularly difficult to control, because codling moths can survive on a wide
array of other fruits including quince, wild hawthorn, crab apples, and English
walnuts. Even when apple growers spray to control the pest in their trees, some
moths survive on surrounding unsprayed hosts. These survivors can eventually
invade and re-infest the apple orchards.
Another trait that favors codling moths' survival is that most of their
livesthe larval stageis spent inside fruit. This protects them from
insecticides and environmental stresses, like extremely hot or cold weather.
Nevertheless, Calkins and other scientists believe pesticide use to control
codling moths can be reducedand perhaps eventually eliminatedby the
use of pheromones, biocontrol agents, and release of sterile males.
Industry People Lend a Hand
The apple industry has an interest in making the areawide pest management
"Codling moths, if left unchecked, have the potential to destroy an
estimated 80 percent of the Northwest's apple crop and 50 percent of the
pears," says Calkins.
"With evidence that pesticide resistance is becoming a problem at sites
in California and Washington, it is time that we changed the orchard IPM system
currently used and implemented alternatives to chemical-based management."
Test sites on commercial orchards are near Parker Heights, Oroville, and
Chelan, Washington; Medford, Oregon; and Randall Island in the Sacramento River
Delta south of Sacramento, California. They range in size from 300 to 1,100
acres and have 68 grower-participants.
In a Yakima Valley apple orchard near Mt. Adams, entomologist
Alan Knight examines codling moth traps to see if there is a population
"Growers have been involved in the project since the start," says
Gaylord Enbom of Wapato, Washington. He grows 11 acres of apples and pears and
is partner in another operation that consists of 120 acres of apples, pears,
"We intend to cooperate to make sure this is a fair test of the
system," Gaylord says, "because we have too much at stake not to.
While we don't know that it will work, we hope it does. We're still in the
learning stage at this point."
Some large growers are already using mating disruption on a fairly large
scale500 to 1,000 acres. They tie sex pheromone dispensers on trees to
confuse codling moth males looking for mates. The dispensers flood orchards
with so much synthetic female moth scent that males find it all but impossible
to find a potential mate. Some entomologists liken it to trying to find someone
in a house of mirrors.
As a result of this confusion, females don't get mated, their eggs are not
fertilized, and the population crashes. Because insecticides are not used,
natural enemies such as parasites and predators are able to increase to the
point that secondary pests such as leafrollers, pear psylla, aphids, and
leafminers are also controlled.
"The goal is to get all orchards in a large area to function as a
complex, sustainable ecosystem where insect populations never build to
destructive levels," says Calkins. "This could take several
The technology for this project has already been developed piecemeal during
the past 30 years at Yakima and at other ARS labs and universities. So the
biggest challenge will be to fit all the pieces together.
here for a brief history of the evolution
"Mating disruption is the key to expanding the areawide pest management
program on commercial fruit," says Alan L. Knight, an ARS entomologist at
Yakima. "This is quite a change from all previous controls based on
"Although we don't yet know the most effective ways to use disruption
in all orchards, we do have recommendations for its use in most instances"
he says. "During the past 3 years in apple and pear orchards with low moth
populations, mating disruption has generally worked as well as insecticides. In
more than 150 orchards, it proved successful 95 percent of the time."
"Our studies," says Calkins, "indicate that today's higher
costs for mating disruption of codling moth can be reduced and made competitive
with conventional insecticide control. This will happen if growers can rely on
disruption to replace four or more sprays," he says, "and provided
that we are able to control secondary pests economically."
Mass production of pheromone dispensers and competition
from additional manufacturers should further reduce costs.
A gentle tap by Oregon extension agent Philip Van Buskirk
dislodges both pests and beneficial insects for identification and
"And," Calkins adds, "once the insect pest populations are
reduced throughout an area, fewer dispensers will be needed, and costs will
continue to decrease."
Monitoring insect populations during the growing season will allow timely
implementation of appropriate control measures. In the past, some growers were
using intuition rather than insect counts to determine when to apply
insecticides. Modern traps will provide needed data.
Changes in farming practices will also help. For example, removing crop
residues can eliminate overwintering sites for moth larvae. Less
labor-intensive methods include planting cover crops that help control weeds
while providing food and a favorable habitat for desirable insects.
Additional cooperators in the ARS codling moth areawide pest management
program include the Washington Tree Fruit Research Commission, county extension
agents, farm advisers, Washington Apple Commission, and Winter Pear Control
Other areawide pest management programs under ARS consideration include
tobacco budworm (a.k.a. cotton bollworm and corn earworm), Colorado potato
beetle, pink bollworm, and corn rootworm. In addition, two weedsleafy
spurge and sicklepodand a plant diseasetomato blightare
potential projects.By Dennis Senft, ARS.
R. Unruh are at the USDA-ARS
Agricultural Research Laboratory, 5230 Konnowac Pass Rd., Wapato, WA,
98951; phone (509) 454-6566 Knight, phone (509) 454-6563 Unruh, fax (509)
"IPM Goes Areawide" was published in the
July 1995 issue of
Agricultural Research magazine.