Currently, the pheromone cards are
not on themarket and have been tested
under a U.S. Department of Agriculture
experimental-use permit. The
UC Berkeley team has applied for a
"Section 18" — or an emergency use
exemption, and Suterra is pursuing
standard registration.
Spring Mountain Vineyard isn't the
only place where sustainable tools are
being tested, explains Cooper.
"There are 250 acres of vines (statewide)
where the pheromone cards are
being tested."
Complementing the insect releases
at Spring Mountain Vineyard, Rosenbrand
applied Applaud, a soft chemical
that only kills insects in early development
stages. "It does not harm adult
insects," notes Rosenbrand. Champ,
Flint, Thiolux, and sulfur dust were
applied to control powdery mildew, at
low rates to minimize injury to beneficial
insects.
A similar insect-release protocol
was repeated in 2007, starting just two
weeks after bud break, but without
minute pirate bugs. "They are so small
that we couldn't track them," he says.
"We also stopped distributing green
lacewing egg cards in mid-  2007,
because we saw that not all the eggs
were hatching, nor did we have any
evidence that the lacewing population
was increasing or even established in
the infested vineyard."
Overall in 2007, 6,055 Anagyrus
pseudococci, 9,450 Coccidoxenoides perminutus,
35,000 Cryptolaemus, and
240,000 ladybugs were released by the
UC Berkeley team, and 250,000 green
lacewing eggs before he stopped using
them. Once again, both parasites were
recovered from mealybug samples
taken throughout the season, and there
was a season-long decline in mealybug
populations. Cryptolaemus larvae were
also observed during monthly sampling
activities.
Measuring effectiveness
"All were effective, to some degree,"
says Rosenbrand. "We are the least
confident about the ladybugs, but
there's good evidence that Anagyrus
pseudococci, Cocc-idoxenoides perminutus,
and Cryptolaemus are effective.
The number of Anagyrus released in
2007 was tripled because they were the
most effective at parasitizing the
mealybug, and greater quantities were
available because UC Berkeley partnered
with Sterling Insectary to produce
the insects. We saw many
Cryptolaemus larvae that overwintered
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between 2006 and 2007 feeding on all
stages of VMB in Spring 2007."
On each release date, the parasites
were distributed every five to ten
vines, to evenly cover the entire block.
"We released what we had from a limited
supply," he adds. "We obtained
them from UC Berkeley, and worked
with Sterling Insectary (in Kern
County) to develop more, but we still
cannot obtain as many as we need to
cover all of the hot spots."
"The number of Anagyrus released
in the experimental block was appropriate
and sufficient," notes Cooper.
"When Rosenbrand states that he
wants more, this would be for other
areas of the vineyard, not for the experimental
area.
"Fewer Coccidoxenoides were released
in 2007 — only 10% of what was
released in 2006. We don't know how
effective those were." It is more difficult
to measure the impact of C. perminutus
because their preferred host
stage is a small nymph—which can be
difficult to collect — and they may fall
to the ground when they pupate, making
them challenging to locate."
Success of insect-release program
How successful was the overall program?
"There was no honeydew on the
clusters during the 2007 harvest,"
reports Rosenbrand. "We saw no need
to go through and remove clusters. We
harvested everything."
In 2007, the researchers conducted a
cluster sampling before harvest and
found 95% of clusters free of mealybug
damage; and 5% of the clusters sustained
minimal damage (an average of
less than 10 mealybugs per damaged
cluster). This was even lower than in
2006, when 81% of the inspected clusters
were free of damage, 18% sustained
minimal damage (as described
above) and 1% sustained major damage.
There were no clusters in either year
that researchers rated as "unharvestable"
on their rating scale.
Jac Cole, Spring Mountain Vineyard
winemaker, recalls that when he joined
the winery in 2003 the vines were
already infested, so he has had no
experience with unaffected fruit from
that vineyard. But the 2007 vintage
produced the best fruit he had seen in
five vintages. "I don't know if it was
coincidence, because I have no data to
look at about fruit prior to the infestation.
But there was no honeydew problem
in 2007."
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VMB overwinters under the bark, and as
the season progresses the population
moves onto the leaves and canes, and
eventually into the ripening fruit.
Pheromone cards for the mating disruption
program at Spring Mountain Vineyard
contain scent = 10,000 female VMB,
released in a six-month period.
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