PO Box 1555, Ventura, CA 93002
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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.
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.
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.
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.
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.