Practical Winery
65 Mitchell Blvd, San Rafael, CA 94903
phone: 415-453-9700 ext 102
email: Office@practicalwinery.com
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May/June 2008
GRAPEGROWING
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
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."
VMB on young bunch
VMB overwinters under the bark, and as the season progresses the population moves onto the leaves and canes, and eventually into the ripening fruit.

DSC_1899
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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