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Biocontrol
Solutions for Pecan Pests 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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Safe Ways to Say
No Nuts to Walnut Pests
Biological control
with beneficial insects makes dollars and sense. No orchard, even one that is
chemically sprayed, can afford to be without biological control. Growers
transitioning from toxic pesticides towards greater reliance upon biological
control by natural enemies typically report as much as 50-75% pest control cost
savings.
Difficulty achieving
satisfactory pesticide spray coverage in large trees is one reason to
experiment with biological control agents that seek out pests with the
precision of laser-guided missiles. Costs and employee safety and liability
concerns with sprays are other reasons. Managing resistance problems that
evolve over a few seasons with chemical pesticides and may also evolve with Bt
treatments can be avoided with greater reliance upon biological pest control
solutions.
Improved plant vigor
and health may also be noted when pesticide stresses on plant physiology are
removed. Besides safety and profit benefits, adding biological control with natural
enemies as a pest control input can also provide valuable public relations and
marketing benefits as a "green", environmentally-friendly alternative
to conventional chemical control.
BIOLOGICAL CONTROL IN ORCHARD AGRO-ECOSYSTEMS
Releasing Rincon-Vitova's
beneficial insects into pecan agro-ecosystems is part of a sound profitable
strategy for achieving biological control and minimizing crop damage.
Rincon-Vitova's natural enemies help police pest populations and stabilize
orchard ecosystems, bringing predator and prey (pest) into better ecological
balance.
Pecan trees provide a
favorable environment for a wide variety of organisms, including several
hundred insect and mite species, most of which are beneficial -- e.g.
pollinators increase fruit set, antagonists suppress pests via niche
competition, scavengers turn debris into vital soil humus and are part of the
food chain, an alternative food source for beneficials when pests are absent.
In orchards where pesticides have not killed off the predators and parasites,
most potential pests go unnoticed, as they are so effectively squelched by
resident beneficials.
The key pests of
pecans are attacked by a wide array of general feeding predators and parasites,
including various species of lacewing, lady beetles, assassin bugs, spined
soldier bugs, syrphid flies and trichogramma. Rincon-Vitova's insectary-grown
beneficial insects (all natural, none genetically engineered) supplement
indigenous orchard biological control organisms and shift the ecological balance
towards sustainable biological pest control by natural enemies.
FARMING WITH BENEFICIALS
Maximizing the
diversity and distribution of selected plant species -- e.g. planting
covercrops or tolerating certain weed species between trees at critical times
instead of herbiciding or discing the orchard floor completely clean -- is a
farming technique useful for increasing orchard biological control. The
strategy behind cover cropping vis-a-vis pest control is increasing resident
insect and arachnid micro-wildlife, thereby expanding the food chain and
supporting a larger army of beneficial pest-fighting arthropods. Thus, after
cleaning up yellow aphids and black pecan aphids in the trees, brigades of
predators and parasites can find shelter and sustenance on cover crops, and be
available to fight future infestations in the trees.
The best cover
cropping strategy may vary from area to area, and is best selected in
consultation with pest control advisers and other sources knowledgeable about
integrated pest management (IPM) techniques like habitat diversity and refuge
management. Rincon-Vitova's philosophy is that orchard cover crops and cultural
practices should be designed to grow beneficial organisms in ecological
environments that emulate natural systems.
USDA entomologist
Louis Tedders has found that a mix of annuals like hairy vetch and crimson
clover performed well to build up aphid predators, die out in summer to avoid
competing for moisture and regrow in the fall after harvest. Dr. Robert Bugg of
the Sustainable Agriculture Research and Education Program at UC Davis
recommends lana vetch, hairy vetch and cereal rye oats in California pecans.
Others find any native or seeded cover that provides a succession of bloom will
help avoid treating for aphids early in the season and foster early
reproduction of parasites of hickory shuckworm and pecan nut casebearer.
At Rincon-Vitova, we
recommend consideration of legume green manure cover crops. Besides injecting
nitrogen into the soil and promoting formation of nourishing soil humus,
legumes and mixtures of legumes, grasses and weeds can be managed to reduce
orchard pest problems. For example, by periodically alternately cutting every
other border of leguminous cover crops, weeds can be kept from going to seed,
while at the same time encouraging composting organisms. Composting organisms
become part of the food chain, nourishing biological control organisms ranging
from beneficial arthropods to predatory nematodes and fungi that aid in the
biocontrol of soil and foliar insects and diseases, such as scab infection.
Rincon-Vitova's
beneficial insects are not designed to be magic bullets applied like pesticides
for instant pest control. Successful sustainable biological control is an
ecological process, and inoculative releases of Rincon-Vitova's beneficials
into the orchard ecosystem to augment existing natural controls is but one
component of a larger sustainable ecological farming system that may take three
to five years to establish. Farming ecologically with Rincon's biological
control inputs gets easier the second and third year, as a reservoir of natural
biological control organisms becomes established.
After the initial
first year biocontrol inoculation, which is best planned out with an IPM
specialist who can monitor progress and advise on release dates etc., smaller
annual maintenance releases of predators and parasites may subsequently suffice
to get a head start on pests and compensate for biocontrol losses to weather,
orchard sprays, pesticide drift etc. Besides helping integrate sustainable
biological control into your farming system, an IPM practitioner can provide
guidance on least toxic, low residual sprays and reduced dosages of
conventional pesticides that minimize disruption of biological control.
Continued attention is advised to nurture biological control organisms from
year to year and detect new pest invasions.
Careful monitoring
and sampling of the progress of biological controls is important because not
all walnut trees or parts of groves get pests at the same time. It is often
possible to identify pest "hot spots" that can be targeted for
treatment with larger numbers of beneficials or spot-treated with least toxic,
low residual spray materials. Knowledge inputs -- e.g. publications like the
IPM Practitioner (BIRC, P.O. Box 7414, Berkeley, CA 94707) and the University
of California's Integrated Pest Management for Walnuts manual -- and staying on
Rincon-Vitova's customer list are also recommended to keep you up to date on
the latest advances in managing pest natural enemies.
To be most effective
and sustainable, biological pest control is best designed into an area. Alfalfa
is the beneficial insect nurse crop for many agroecosystems. Spraying
"insectary" crops like alfalfa is a guaranteed recipe for major pest
infestations in all area crops; the media seems to have missed this message in
the recent sweetpotato/poinsettia whitefly scourge.
Slight modifications
in the way one farms can emulate more natural systems, and encourage beneficial
insect armies to attack walnut pests. For example, planting cover crop or
alfalfa refugia (safe havens that are never sprayed) mimics the natural
movement of beneficials from crop to crop. Biological control is maximized when
alternate crops act as field insectaries, growing large populations of
pest-fighting predators and parasites. Refuges of alfalfa and other legumes
attract large numbers of aphids, mites, and worms (none of which attack
walnuts) that nourish general predators which can move into the trees to eat
walnut pests.
A form of
intercropping known as strip cropping (e.g. strips of cover crops between at
least some tree rows) and maintaining small fields of unsprayed alfalfa are
ecological farming practices Rincon-Vitova recommends to create on-farm
insectaries, growing your own free supply of hungry predators and parasites to
devour pests. General predators that feed on a wide variety of prey eat early
season pests in unsprayed alfalfa and cover crops. Several generations later
their offspring form the basis of biological controls that enter the canopy of
new spring growth occurring in walnut trees.
Alternate strip
harvesting of alfalfa and cover crop beneficial insect refuges (safe havens
that are never sprayed) keeps the plants attractive to arthropod food sources
that nourish beneficials throughout the season. As the season advances, begin
mowing alternate strips when cover crops or alfalfa begin to bloom; cut half
and let this start to grow back before mowing the alternate strips. Avoid
broad-spectrum pesticides at all costs in early season for maximum production
of predators and parasites. This "battle of the bugs" in adjacent
crops takes place without damage to the walnuts.
USING RINCON-VITOVA'S BIOLOGICAL CONTROL INPUTS
Maintaining
biological control in walnuts is an ongoing process involving introduction and
conservation of natural enemies and careful monitoring. Periodic maintenance
release of insectary-grown beneficials timed to focus on developing pest
hotspots aids in season-long biocontrol. Conservation of natural enemies is
facilitated by phasing out hard pesticides interfering with biological control.
Repeated spraying of hard-to-kill resistant pests devastates beneficials, and
in the long run creates even more pests.
Where walnut's
beneficials are destroyed by spray programs or starved away by lack of
alternate prey, releases of Rincon-Vitova's green lacewings and other
beneficials helps restore the natural checks and balances found in unsprayed
ecosystems. Early season release of insectary-grown beneficials is the backbone
of reestablishing biological control. It is like restocking the fish pond when
one starts releasing Rincon's beneficials to rescue such natural-enemy-depleted
farms from the pesticide treadmill.
Rincon-Vitova
Insectaries tries to make the transition from pesticides to ecologically based
biological control as smooth as possible by continually collecting new strains
of beneficials from heavily sprayed agroecosystems. Though we do not
specifically test natural enemies for ability to withstand chemical sprays, we
believe that some of our insects, particularly our green lacewings, great
all-around predators, have been successful in transition situations due in part
to this hardiness and ability to withstand some chemical residues.
General predators
such as green lacewings and lady beetles are released to insure timely presence
when aphid prey are in the cover crop. Ideally, releases are started early when
the first pests enter the field. These early releases are forced into the trees
when walnut aphids appear. The same beneficials control spider mites after
aphids come under biological control. Later season worm control is an
additional benefit of letting small early season populations of beneficials
expand their numbers in a pesticide-free environment.
If it is necessary to
knock runaway pest populations down to levels that small populations of
newly-introduced beneficials can easily mop up, use least-toxic, low-residual
spray materials. The goal of spraying (selective use of least toxic pesticides)
is lowering pest populations to tolerable levels, not pest eradication. Low
pest populations and innocuous alternate prey are necessary to feed biological
control organisms. Without prey, predators are scarce. Hence, it is essential
that a few minor pest situations develop, in order to obtain and maintain a
buffering natural enemy complex within the walnut ecosystem, and control major
pest problems as they develop.
A natural enemy
complex of several dozen species building up over time may be necessary for
sustained biological control of key caterpillar pests, such as the codling
moth. An advantage of releasing Trichogramma reared in Rincon-Vitova's
insectary is that this pinhead-sized parasite kills codling moth in the egg
stage before it can damage fruit or nuts.
Trichogramma is one
of Rincon's specialties. Releases work best in conjunction with natural enemy
conservation measures such as avoiding harsh sprays toxic to indigenous
beneficials and growing cover crops with nectar to nourish wasps attacking
codling moth larvae and pupae. Rincon started out rearing Trichogramma for
cotton growers in 1960, and has since reared several Trichogramma species
adapted to a wide variety of crops and pests. One of our most popular
strategies is initially releasing large numbers of Trichogramma and green
lacewings to colonize groves, then following up with a series of smaller
releases to ensure long-term establishment.
We currently
recommend purchase of Trichogramma platneri for release in west coast orchards
against codling moth and a wide variety of fruit and leaf worms, including
navel orangeworm, redhumped caterpillar, fall webworm, Oriental fruit moth and
twig borers. Trichogramma minutum is the species of choice for the East Coast.
Releasing the wrong species can have adverse consequences, which are explained
in a special bulletin. We can explain this further over the phone when
discussing your order.
Customers on accounts
are informed through periodic mailings of new beneficial species, some of which
are so scarce that only very small quantities can initially be provided for
inoculation. In addition, where demand is sufficient, we can on special request
collect or obtain rarer natural enemies not normally available commercially.
Technical bulletins
are available for all the beneficials that we sell. A quality control
specialist works to insure that the best possible product is sent out.
Nevertheless, sometimes shipments of fragile insects can arrive injured or
otherwise not meet expectations. As we stand behind all product shipped, please
feel free to contact us should you ever feel that there is a problem or that a
replacement may be necessary.