Skeet and I will be in big trouble. We both have blueberries and citruses -
Joe
Source:
http://www.centralvalleybusinesstimes.com/stories/001/?ID=8094
DAVIS
March 12, 2008 5:06am
Long-time pest now munching on blueberries, too
Entomologist seeks solution
Thrip-damaged blueberry plant
The Central Valleys navel oranges are not enough for a tiny pest thats getting some top-level scientific attention. Citrus thrips are expanding their diet to include the growing commercial plantings of blueberries.
"Citrus thrips are best known for the scarring damage they cause to navel oranges in the San Joaquin Valley, but with the recent plantings of blueberries, this pest has taken damage to a whole new level," says David Haviland, a University of California Cooperative Extension farm advisor.
"With the high value of blueberries and potential damage in the thousands of dollars per acre, management of this pest is critical, he says. Current practices are to spray fields multiple times with insecticide after harvest through fall. However, with the propensity of citrus thrips to develop resistance to insecticide, and spinosyn-based insecticides being the only effective products registered for blueberries, alternate approaches are needed."
Mr. Haviland is leading a team of experts in a three-year study of the problem and the best solutions. They have developed monitoring and treatment guidelines to help growers avoid using unnecessary pesticide applications.
Funding is from the UC Statewide Integrated Pest Management Program.
Unlike flower thrips that prefer to feed within blossoms, citrus thrips prefer to feed on new growth. This makes blueberries an excellent host because they produce new, tender growth at the end of their shoots from June through October.
Citrus thrips feeding on blueberry foliage results in a wide range of symptoms including crinkled or misshapen leaves, stem scarring, stem discoloration, shortened internodes, and even death of the shoot tip. In some cases, death of the tip causes the buds at the bases of leaves to begin to grow, giving the shoot the appearance of an upside-down witch's broom.
Mr. Haviland and his team showed that an average of 35 thrips on a shoot tip for a one-month period in August caused a 52 percent reduction in the length of new shoots. However, damage didn't stop there. Blueberry fruit during the spring develops at the tips of the shoots from the previous year. This means that citrus thrips feeding causes reduced growth that results in less fruiting wood, and, therefore, less fruit.
The UC team is developing an integrated pest management program for the destructive pest. They are currently investigating alternatives to insecticides, such as the use of repeated applications of high pressure water to knock immature thrips off of the plants, and the use of Beauveria bassiana, a fungus that acts as a parasite of the pupal stage of the thrips that reside in the soil.
