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24 WINES&VINES April 2018 I t has been a long time since I wrote a column about the use of biopesticides by wine grape growers. In fact, it has been seven years since my column "Biopesticides Come of Age" appeared in the July 2011 issue of Wines & Vines. I have seen quite a bit of trade press lately about use of biopesticides by growers in the United States, so I thought it would be a good time to do an arm- chair review of their current use in vineyards to see if they can be considered mainstream pest-management tools. My review showed that the use of biopesticides in California wine grape vineyards, when expressed as a percentage of total pounds applied, rose nearly two-thirds over 10 years, and that they have been very effective in certain key situations. However, they have a long way to go before they become mainstream, accounting for 1% of total pounds of all pesticides applied, excluding sulfur. For the review, I did a quick check of California Depart- ment of Pesticide Regulation's Pesticide Use Reporting database for any change in the amounts of biopesticides used annually in vineyards over the past 10 years. I then contacted growers, farm advisors and manufacturers around the United States and asked them their impres- sions about the use of biopesticides by wine grape growers in their region and any comments growers are making about them. Biopesticides have several desirable characteristics compared to many conventional, synthetic pesticides. They leave no problematic chemical residues on the crop; re-entry time after a spray is 24 hours or less; pre-harvest intervals are short (they have very little environmental impact); often their modes of action are such that development of resistance is not as likely as with conventional pesticides, and getting an active ingredient to market costs in the neighborhood of $3million to $5 million compared to $150 million or more for a conventional pesticide. While it is not possible to get an accurate summary of total annual use of pesticides on wine grapes in the United States, it is possible to get this information for California wine- grape vineyards because California grow- ers have to submit pesticide use records each month to their local ag- riculture commissioner. The California Department of Pesti- cide Regulation summarizes this data and publishes annual Pesticide Use Reports (PUR). Since California accounts for almost 90% of the winegrape production in the United States, producing both premium as well as non-premium wine- grapes, the PUR results are representative of the U.S. industry as a whole. I compared the use of biopesticides in California in 2005 with those used in 2015, the latest year the annual PUR report is available. Pesticide use is recorded by ac- tive ingredient, so I looked at data summaries for the following biopesticide active ingredients which I believe to be the most commonly used: Bacillus subtilis, B. pumi- lis, B. amyloliquefaciens, and B. thuringiensis; Pyrethrin, Aurobasidium pullulans, and spinosad. The use of biopes- ticides has increased significantly as a portion of the total lbs of all pesticide active ingredients applied to wine- grapes (excluding sulfur dust), going from 0.67% of the total in 2005 to 1.00% of the total in 2015. However, they still account for only a very small amount of the pesticides applied to winegrape vineyards. Two of the biopesticide active ingredients, B. subtilis and B. amylo- liquefaciens, account for 87% of the total lbs of biopes- ticides used in 2015. Causes of increased biopesticide use After communicating with several growers, farm advi- sors and manufacturers in California, Oregon, Washing- ton and New York, it appears that even though the use of biopesticides is low when compared to the use of synthetic pesticides, many growers are recognizing their strengths and limitations and acting accordingly. For example, for large wine grape growers in the Central Valley of California, biofungicides provide 10-14 days of protection against powdery mildew, but up to 21-plus days of protection is needed to make spray programs economically feasible, so their use is limited. Vineyard disease pressure is much higher in wetter climates like New York than it is in the Mediterranean climate of Cali- fornia. It comes from not only powdery mildew but also downy mildew, black rot and Phomopsis. So far, biopes- ticides have not shown the ability to manage the disease pressure under these conditions as effectively as conven- tional pesticides. Vineyard View n CLIFF OHMART Biopesticide Use Not Yet Mainstream Despite Numerous Advantages