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Biocontrol Solutions for Grapes PO Box 1555, Ventura, CA 93002 800-248-2847 *
805-643-5407 * fax 805-643-6267 questions bugnet@rinconvitova.com orders orderdesk@rinconvitova.com web www.rinconvitova.com |
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Biological control with
beneficial insects makes dollars and sense. Costs of sprays, scheduling sprays
when workers are not present, managing residue and resistance problems can be
avoided. Difficulty of achieving satisfactory spray coverage by itself is
incentive enough to seek more sustainable systems of pest management. A savings
of 50 to 75 percent in pest control costs is often reported in the first two
years of transition to predominantly biological control. Public and worker
liability risks, even insurance costs, may be reduced. As if this were not
enough, there are also public relations benefits from using this
"green", environmentally-friendly alternative to conventional
chemical control.
BIOLOGICAL CONTROL UTILIZES A COMPLEX OF NATURAL
ENEMIES
Minimizing crop losses
and optimizing crop production through biological control depends on the
diversity of habitat for arthropod wild life. To foster natural enemies of
pests of grapes in conventional farming systems it is necessary to manipulate
these enemies as much as the crop is managed, both must be farmed together.
Cultural practices must be designed in the vineyard ecosystem to grow grapes
and covercrop plants and the beneficial organisms in ways that more closely
emulate the natural systems in which they evolved.
Slight changes in
farming can overcome some of the cultural practices taken for granted under
conventional chemical farming that form habitats for biological controls.
hedging, refuge management can make a difference in the behavior of both pests
and the beneficials that attack them. Legume green manure crops add to the
diversity of organisms provided by resident weeds. When managed by
periodically, alternately cutting every other border, they keep the weeds from
going to seed and further increase the diversity of composting organisms. This
process adds humus to the soil for the grapes as well as fosters the food
chains that feeds the sets of beneficials in the biological control of insect
pests and diseases. For example protozoa have been reported to diminish Xanthomonas campestris ,"Blight".
Baker and Cook state that "virtually all pathogens that spend any part of
their life cycle in soil outside the protection of their host are subject to
attack by predators and parasites". Many different micro and macro organisms
including beneficial predatory nematodes and fungi add to this biological
control.
RELEASES OF BENEFICIAL INSECTS FAVORS BIOLOGICAL
CONTROL
Vineyard managers are
fortunate that only three of the 25 potential pests directly attack the fruit
which is the market portion of this crop. All other potential pests have
adequate natural occurring sets of beneficials that subdue them. Even these key
pests of the fruit are attack by a wide array of general feeding predators and
parasites.. Releases of specific insectary grown beneficials to interact with
natural occurring beneficials augment biological control of all pests making
biological control safe, permanent and economical.
MONITORING
In biological control
programs, monitoring takes on a whole new meaning from that used in
conventional total chemical eradication programs. Predator and parasite
management augments biological suppressive forces so that pest population
levels do not rise so explosively. The non economic pest population grow more
and more natural enemies that later in the seasonal growth cycle will control
major fruit pests . The goal in IPM is to restore biological control and not
eradicate the pests. For example, not all grape vines or parts of vineyards get
pests at the same time. Careful monitoring and sampling of the progress of
biological controls can often identify the "hot spots" that can be
treated with larger numbers of beneficials or spot treated with least toxic,
low residual spray materials Not all pesticides have adverse effects on the
balance of pests and their natural enemies, and certain dosages of conventional
pesticides are less disruptive to biological controls. It is important to point
out that insects, mites, and weeds etc. are pests only when they affect our way
of life beyond tolerable limits. It is only the intolerable numbers that
constitute the label pest!
Identifying the problem
is the initial step to re-establish biological control of grape pests. Where
grape's beneficials are destroyed or starved away by spray programs designed
for resistance, it may be necessary to restore many of the natural enemies to
the farm. Beneficial insect releases help restore the checks and balances found
in unsprayed natural ecosystems. Planting covercrop refugia (safe havens that
are never sprayed) to attract and grow the predators and parasites can provide
a field insectary to attract and grow the maximum numbers of beneficials to
maximize biological control.
RVI BENEFICIALS
The beneficial insects
(all natural, non-genetically engineered) supplied by Rincon - Vitova
Insectaries augment other natural occurring predators and parasites grown in
the irrigated covercrop refuges. The least pest damage to the market crops
occurs where the covercrop refuges trap the pests away from the vineyard.
Refuges of alfalfa and other legumes attract large numbers of soft bodied
aphids, mites, worms (none of which attack grapes) that are prey to feed
general predators of grape pests. Alternate strip harvesting of this covercrop
refuge will keep the plants attractive to these herbivores throughout the
season. The sets of natural enemies increase in numbers by feeding on their
prey in this ecosystem of covercrop plants This "battle of the bugs"
takes place without damage to the grapes. The alternate strip cutting favors
the biological controls
MAINTAINING BIOLOGICAL CONTROL
Maintaining biological
control in grapes is an on - going process involving introduction and
conservation of natural enemies and careful monitoring. Conservation of natural
enemies is facilitated by phasing out hard pesticides interfering with
biological control, as well as by periodic maintenance releases of beneficials.
Season long biological control is predicated upon monitoring the progress of
biological control throughout the various plant developmental stages. General
predators that feed on a wide variety of prey enter the vineyard by feeding on
early season pests in the covercrops. Several generations later their
off-spring form the basis of biological controls that enter the canopy of new
spring growth occurring in the grapes. Periodic releases of insectary grown
beneficials timed to focus on the developing pest spots in the vineyard is an
alternative to spraying and killing beneficials as well as pests. Repeated
spraying of resistant pests that are hard to kill devastates beneficials and
creates ever more pests in the long term.
The common sense
approach would be to back away from conventional chemical controls by following
a program of integrated pest management (IPM). One of our most popular
strategies is initially releasing large numbers of beneficials to colonize the
vineyard, following up with a series of smaller releases to ensure long - term
establishment of pest destroying natural enemies. Periodic releases the egg
parasite, Trichogramma platneri (TCM)
that attacks the eggs of a wide range of pests including codling moth, navel
orangeworm, red humped caterpillar, fall webworm. Many other moths and
butterflies that interact with covercrop plants are prey for this tiny beneficial
wasp. General predators such as ladybugs and green lacewings larvae are
released to insure timely presence when aphid prey are present in the
covercrop. These early releases are forced into the vines when aphids appear.
These same insects control spider mites when aphids come under biological
control
Start releases early
when the first pests enter the field. If it becomes necessary later on to knock
down runaway pest populations to levels that small populations of
newly-introduced beneficials can easily mop up, use the least-toxic,
low-residual spray materials available. The goal for all spraying (selective
use of least toxic pesticides) is to lower the pest population to a tolerable
level and still restore biological control.
GETTING STARTED
CULTURAL CONTROLS, Plant the legume covercrops for field insectary
refuges for beneficial insects. As the season advances begin mowing alternate
strips when plants start to bloom. Cut half and let this start to grow back
before mowing the alternate strips. This management maximizes the populations
of beneficials on the farm. Broad spectrum pesticides are avoided at all costs
in early season. Release early season insectary grown beneficials that are the
back bone of reestablishing biological control. It is like "restocking the
fish pond" when one starts to rescue such natural enemy depleted farms
from the pesticide treadmill.
SPRAYING
Avoid pesticide (including herbicides and certain sprays for pathogens) to the
extent possible that interfere with beneficials. Preventative chemical
treatments, particularly systemic pesticides that interfere by almost
eradicating early season pests must be avoided. It is essential that a few
minor pest situations develop in order to obtain and maintain a buffering
natural enemy complex within the grape ecosystem that will control major pest
problems later on.
IPM in grapes is based
on the ecosystem concept that stresses the broad range of interactions of
diverse sets of natural enemies affecting potential pests of this crop. Although
conventional farming practices greatly simplify these predator prey
relationships, slight modifications in the way one farms can emulate more
natural systems to take advantage of natural enemies of grape pests. Getting
started requires a desire to use these interactive beneficials throughout the
year. Short term benefits from over reliance on pesticides will not lead to
long term gains in biological control. The second and third year are always
easier that the first. Biological control in grapes is economical, safe and
profitable.
References:
UC IPM Manual
Publication 3270, Grape
Relevance of Ecological
Concepts in Practical Biological Control Dr. Peter W . Price, Beltsville
Symposia in Agricultural Research #5 Biological Control in Crop Production
1981.
The Nature and Practice
of Biological Control of Plant Pathogens, R. James Cook and Kenneth F. Baker , 1983.