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
Rosenbrand and Cooper note that the program is still in the experimental stage. "We're still testing the concept and doing research," says Cooper. "Especially as we fine-tune release rates, timing, the ability of these beneficials to establish populations in vineyards, and the optimal combinations of insects to release."
Rosenbrand adds, "If this were 100% proven, Cooper would not be working with us as a research scientist to learn and explore the effectiveness of using bio-control to control VMB."
Other research plots in California
In addition to working with Spring Mountain Vineyard, in 2006 and 2007, the UC Berkeley team had about 12 other research plots located in Napa County, Sonoma Valley, the Central Coast region, the Lodi area, and raisin vineyards in the San Joaquin Valley (these were directed by Glenn Yokota, Cooper's counterpart at the Kearney Agricultural Center).
Cooper reports similar results from around the state. "Crop damage was minimal in all plots and both parasites were recovered in monthly mealybug samples."
Daane notes that a key is to first suppress the mealybug densities with properly applied insecticides. The sustainable tools will not rapidly reduce large, damaging mealybug populations, but they have proven capable of maintaining low density populations below damaging levels.
In 2008, Cooper will supervise eight plots in the North Coast, eight in the Central Coast, and eight in Lodi, but those in Lodi will not use predators, only parasites. Yokota will supervise six plots in the San Joaquin Valley. The researchers plan tomonitor each plot at least once monthly.
The UC Berkeley team is also investigating which natural enemies might work best together. Cooper explains that, in a Carneros vineyard, they have isolated individual vines in large, walk-in cages and added different combinations of beneficial insects (A. pseudococci, C. perminutus, and C. montrouzieri). The researchers hope to determine how the species interact to control VMB populations.
Any vineyard manager who has a large mealybug infestation should first knock it back with an insecticide, notes Cooper. "The next step is to then deploy bait to target Argentine ants." As mentioned above, Argentine ants disrupt the activity of beneficial insects, so ant populations must be controlled before biological control can be successful. If someone tries to release insects to control the VMB, they won't do the job well if there are large Argentine ant populations which disrupt the beneficial insects.
"When we were working under the Napa County compliance agreement," Rosenbrand recalls," before we began the bio-control program, we sprayed many times per year
with Dimethoate, Lannate, Applaud, Provado, and Lorsban. The attempt with all this was VMB eradication!
"In 2006, we sprayed twice with Applaud, and once in 2007. Applaud is a soft chemical which is a growth regulator and it does not allow nymphs to become adults. The Applaud applications were not intended for ant control (and probably have little impact on the ants)."
Stripping the bark from vines to help to expose mealybugs is recommended by Rosenbrand. "We stripped bark manually in 2003, but have not stripped since. Bark-stripping by hand is incredibly expensive. There is a new tool to air-blast the bark, which should help decrease the cost of manual barkstripping.
"Someone who has a mealybug problem can get a head start by controlling antswith the use of ant bait stations, and reducing VMB populations through bark-stripping, and spraying insecticides, to prepare the way for beneficial insects."
All of these techniques are essential to bring VMB populations from high densities down to low to moderate densities. At these lower densities, the sustainable management tools described here can then be employed to manage VMB populations.