2002-2004 Specialty Crops Research Program
University of California

Principal Investigators: Walt Bentley

Project title: Developing a Management Program for San Jose Scale and Oriental Fruit Moth for Organic and Non Organic Stone Fruit Farmers

San Jose scale. The research objective is to predict San Jose scale (SJS) fruit infestation based on late fall or winter spur sampling to allow farmers to 1) determine the need for treatment (even with oils alone), and 2) determine the severity of that infestation (possibly needing the very effective growth regulators in addition to oils). I have one year of data relating 2001 infestation to December 2002 spur infestation with a highly significant (P>0.01) correlation (R2= 0.85). I am now attempting to predict the severity of infestation in 2002 (harvest will begin in August) based on spur sampling last spring. I will utilize two 1.5-acre plantings of early and late harvested fruit (24 plots). Work will begin in the winter by sampling a minimum of 200 spurs from each variety, counting SJS to determine scale stage of growth. Double sided sticky tapes will be used to trace scale development and abundance. At harvest (late June--Black Amber and Queen Rosa, late July--Royal Diamond, early August--Rosemary), 200 randomly selected fruit will be evaluated for scale infestation. The relationship between spurs and fruit will be done using simple correlation analysis. The latest harvest variety will be held another month to simulate late harvested fruit. Results will be presented at two the winter stone fruit meetings. A very simple survey, ten questions maximum, will be used to measure adoption of this technique. The California Tree Fruit Agreement’s mailing list will be used. The research will require three more years (we will have this years work on a smaller scale).

Oriental fruit moth. Oriental fruit moth (OFM) has been under a biological control program in Western Colorado since 1946. Macrocentrus ancylivorus, a parasite, is available for purchase and can be released to aid in management of this pest during August and September. Small cage studies will be done on individual trees validate parasitism of OFM in California, although previously demonstrated (Flanders, 1940). M. ancylivorous does not winter on OFM; it requires a larval host to winter. It does survive on alternate hosts such as the sunflower moth, ragweed borer and strawberry leafroller. We plan to establish a half-acre sunflower adjacent to a three-acre planting of Crimson Red peach at the Kearney Agricultural Center. Sunflower moth will be established in a sunflower planting and serve as wintering hosts for the parasitoid. The planting will be established in spring 2003 and artificially infested with sunflower moths. Sunflower heads and moths will be caged and exposed to 5-10 female M. ancylivorous. These will remain caged until spring when the netting will be removed and the parasites will be allowed to emerge. The two aspects of the study are 1) to attempt establishment of the parasitoid on an alternate host so it may winter, and 2) to attempt releases of 1,000 parasitoids per acre. There will be three such orchards. The wintering study will be done over 2003 and 2004 and evaluated in 2003 and 2005. The inundative release study will be done in 2003 and 2004. Parasites will be evaluated monthly. This portion of the study will be demonstrated in the Pest Management Alliance program.