$1.6 billion-a-year lettuce and celery industry along California's
Central Coast, which accounts for 60 percent of the nation's supply,
faces insect problems that no individual grower or pest control
advisor (PCA) can solve alone.
project set out to develop and evaluate an environmentally friendly,
economically viable, pest management approach to the pea leafminer,
Liriomyza huidobrensis, which attacks young celery and lettuce
plants. Then the project shifted gears to deal with the critical
problems emerging from the appearance of a new pest, the lettuce
aphid, Nasonovia ribis-nigri. The goal of this project was to
control the insects more effectively by refining, validating and
sharing a commercial-scale integrated pest management system that
can be adopted by a high percentage of the coastal lettuce and
summer and fall outbreaks of the pea leafminer can produce 10
to 15 million larvae per acre. The hatching pea leafminers burrow
deep in the heart of the developing lettuce and celery, feasting
on tender, young plants and depositing a brown "mining"
trail of damage as the pests work their way through the plant.
In 1999 Salinas Valley growers discovered the lettuce aphid, a
heretofore-unknown pest, invading their 115,000 acres of lettuce
and celery fields. The aphid infests the base of the lettuce leaf,
making the insect difficult to control and the product unacceptable
in the marketplace. The remarkably persistent aphid resists control
by most conventional pesticides.
Valley's five major vegetable companies and industry leaders
- Dole Fresh Vegetables, Tanimura & Antle, Inc., D'Arrigo
Bros. Co., Duda California/Gene Jackson Farms, Inc., Commodity
boards -- the Lettuce Research Board, the California Celery
Research Board. Input suppliers-- Western Farm Service and
Soilserv, Inc., University of California Cooperative Extension
Farm Advisor in Monterey County.
growers lose productivity when they're forced to strip away damaged
leaves and stalks. At worst, entire fields are so damaged that
they never make it to harvest. The explosion of the pea leafminer
and the lettuce aphid is literally eating into gross revenues
of $5,000 to $6,000 per acre for lettuce and $8,000 to $9,000
per acre for celery. At the same time, pesticide costs have nearly
doubled in the past four years, reaching as much as $800 per acre.
And the pesticides are not coming close to containing the crop
damage. The pests weaken and stunt the growth and cause leaves
and stalks to be discarded during harvest. These pest infestations
have increased the number of pesticide applications, the number
of chemicals used, and the cost of pest management--without achieving
intended levels of control.
a team approach of sharing more accurate information about the
leafminer and the aphid, and by agreeing on a set of consistent
and team-validated pest management strategies, the new decision-making
system developed by this project has allowed PCAs and their growers
to take advantage of a full range of pest control techniques.
The project published a picture guide to pest and beneficial insects
and developed a website, http://ccvipmp.ucdavis.edu,
which posts newsletters, trial protocols, insect photos, and data
from the demonstration plots.
Pesticide Treatment Menu Guidelines were:
registered classes: organophosphates, carbamates, and pyrethroids
organophosphates, carbamates, and pyrethroids when alternative
registered chemistry is available.
all classes of registered biologicals.
on using biologically based materials.
Conservation of natural enemies.
typical spray regime.
20 growers participated in the project, using the experimental
pest control program on 46 field demonstrations covering 667 acres.
These included 29 head lettuce, 10 romaine, and 7 celery fields
from Watsonville to Oxnard. This acreage conservatively represented
a risked investment of $2 million. In these fields, the reduction
in the number of applications of organophosphates, carbamates,
and pyrethroids for the IPM treatments compared to the standard
was 87 percent for head lettuce, 88 percent for romaine, and 72
percent for celery.
switch to the use of the IPM treatments had little effect on harvest
quality or quantity. There was no significant difference in yield
for romaine or celery. In head lettuce, 12 percent of the replicated
field trials had significantly higher yield from the IPM treatment.
However, many of the "softer" IPM materials are more
expensive than older OPs, carbamates, or pyrethroids. Thus there
was a higher cost for the IPM treatments, up to $0.08 per carton
higher. This project has changed the way chemicals are used to
control the pest complex, thus reducing reliance on Food Quality
Protection Act (FQPA)-targeted insecticides and increasing the
use of natural enemies. However, eliminating FQPA-targeted materials
is not possible at this time. One or more of the excluded pesticides
was used on the IPM treatment in 38 percent of the head lettuce,
29 percent of the romaine, and 100 percent of the celery trials.
the vegetable companies partnering on this project grow and ship
about one third of the lettuce and celery in California's Central
Coast region, which itself accounts for 60 percent of the nation's
supply. The changes in decision-making skills among the companies
and their cooperation in the project have not only improved their
ability to handle difficult pests, it has also yielded a 30 percent
reduction in organophosphate use and the overall reduction in
the number of OP applications over all fields was 82 percent.