Farmers
must check
cotton
terminals
on
a regular schedule
for
small worms
and
eggs as part of
an
integrated pest
management
plan.
|
|
|
| Satsumas and oranges are among the crops grown at the Louisiana State University Agricultural Center's Citrus Research Station. Louisiana's citrus industry was threatened in 1994 by the citrus leafminer moth, but scientists introduced a tiny black wasp that has kept the leafminer's numbers manageable. |
Farmers
must check
cotton
terminals
on
a regular schedule
for
small worms
and
eggs as part of
an
integrated pest
management
plan.
|
Scientists at
Louisiana State University (LSU) Agricultural Center introduced the tiny
black wasp, Ageniaspis citricola, into the citrus groves of southeastern
Louisiana a few years ago to kill the citrus leafminer, a moth that threatened
to destroy the state's citrus crops.
The moth, which is not much bigger than the wasp, first appeared in 1994,
somehow making its way from Asia into Louisiana. Growers tried chemical
control but were frustrated by its high cost and relative ineffectiveness.
Ageniaspis citricola, also originally from Asia, has not only adapted
to Louisiana, but has so far kept the citrus leafminer manageable.
No Reduction in Yields
"We're never going to
be rid of citrus leafminers, but because of the wasp, we're not seeing
any yield reduction because of the leafminer," said Wayne Bourgeois, associate
professor at the LSU Agricultural Center's Citrus Research Station, which
is located south of New Orleans near the Gulf of Mexico coast.
Seth Johnson, entomologist on the LSU campus in Baton Rouge, headed up
the team of scientists that introduced the wasp.
"This is an example of classical biological control," he said. "We worked
with scientists at the University of Florida, where they are having some
of the same problems."
Louisiana's citrus industry, though small compared to the citrus industry
in Florida, contributes nearly $5 million to the state's economy. This
contribution could have been lost without IPM.
IPM Use Necessary in Louisiana
Use of IPM is critical
in Louisiana. The state has a multitude of soil types, abundant water,
and semitropical climate that all support a diverse and dynamic agricultural
economy, but it also has long growing seasons, a humid environment, and
high temperatures- all of which cause problems with insects, pathogens,
weeds, and nematodes.
The Louisiana Agricultural Experiment Station (LAES), the research arm
of the LSU Agricultural Center which has long recognized the pest problem,
has 73 research pest management projects involving 57 scientists. Nearly
25 percent of grants and external funds are devoted to pest management
research, according to David Boethel, LAES assistant director.
By definition, IPM- a holistic, systems approach that frequently requires
multidisciplinary cooperation-encompasses multiple control tactics including
biological control, cultural control, host plant resistance, pesticides,
and, most recently, transgenic technology, which combines aspects of the
other four strategies.
Other IPM Programs Also Effective
Use of the black wasp to save the citrus industry is just one example of the impact of IPM in Louisiana. Others include programs with soybeans, cotton, sugarcane, rice, and dairy cattle:
- IPM tactics for soybeans
include economic thresholds, selective insecticides, trap crops, conservation
of biological control agents, insecticide resistance monitoring, weekly
scouting of fields, and use of early-maturing varieties to escape late
season migratory defoliating pests.
Soybean insect pest management has resulted in a cost-effective program
that has minimized insecticide use. The trap crop technique exploits the
behavior of two major pests, causing them to concentrate in small areas
of the soybean crop where they can be managed with reduced amounts of insecticide.
Not only is this tactic economical, but it reduces the pesticide load in
the environment.
Although soybeans are grown near environmentally sensitive areas, no environmental
disruption or disaster has been associated with insecticide use on the
crop in the past 30 years. During this time, soybean acreage has grown
to a peak of 3.45 million acres. The cost of insect management constitutes
less than five percent of the average production costs, which is remarkable
considering the heavy insect pest pressure facing Louisiana producers.
-Integrated resistance management (IRM) is a critical part of IPM in cotton in Louisiana, a commodity valued at more than $500 million annually. The IRM program has prolonged the useful life of many insecticides necessary to produce cotton economically. Entomologists and agricultural economists have estimated that the loss due to resistance to a single insecticide class, the pyrethroids, would double the cost of cotton insect control in the mid-South and would decrease cotton yields by $34 per acre. The IRM plan also includes preventive recommendations to help delay development of resistance to Bt-cotton in tobacco budworms. Finally, from resistance-monitoring studies in conjunction with the IRM program, cotton producers obtain information about which insecticides no longer provide sufficient control of target pests. By decreasing non effective insecticide applications, producers decrease insecticide use in general.
-Varietal resistance to pests is one of the primary means farmers have to manage pests, and LAES sugarcane varieties began making an impact on the Louisiana sugar industry in 1990. LCP 85-384 was released in 1993 with good disease resistance and about 20 percent higher yields than other varieties. More than half the Louisiana sugarcane acreage is now being grown with LAES varieties and the LAES sugarcane breeding program will continue to have a positive impact on the state's sugarcane industry.
-Sheath blight and rice blast, the two most destructive rice diseases worldwide, are major constraints on rice production in Louisiana. Several rice breeding lines with resistance to sheath blight and blast are in advanced stages of development. Release of a resistant variety will result in a savings of millions of dollars, increased yields, and reduced use of expensive fungicides.
-LAES scientists have
found that controlling the horn fly has had significant economic impact
on Louisiana's cattle industry. Weaning weight of calves from herds where
horn flies were controlled was increased by 14 pounds per head. Application
of this technology translates to about $10 net income per head or a total
of more than $5 million annually.
 |
Dale Pallet, Extension entomologist with the Louisiana State University Agriculture Center, checks the stalks of sugarcane plants for signs of sugarcane borers. In order to apply pesticides only when borer numbers reach a certain level, farmers must make such weekly checks between mid-June and mid-September. |
