The Effect of Application and Timing of Kryocide on Fluoride Levels in Wines

The main purpose of this experiment was to investigate the relationship between various rates and timings of Kryocide applications on a red and a white winegrape variety and possible fluoride levels in finished red and white wines made from those treated grapes. In addition, the efficacy of Kryocide under these new treatment regimes and recommendations following the outcome of the experiment were other objectives. The presence of fluoride in wines has been specifically identified as a problem to the wine industry in the past three years. Preliminary research at CSU Fresno in 1990 and 1991 has shown that there is a correlation between Kryocide applications at bloom and fluoride levels in wines made from Kryocide-treated grapes. However, due to O.I.V. stipulations, further research has been requested to see if lower rates and/or timings would be effective in: (1) keeping fluoride levels below the 3 ppm limit, and (2) controlling Western Grapeleaf Skeletonizer and Omnivorous Leafroller, the two major insect pests controlled by Kryocide. The results indicated that applications of Kryocide made later than at bloom, and multiple applications of Kryocide, contribute to increased levels of fluoride in wines made from those treated grapes. Particularly, a triple application of Kryocide, which put on a total of 19 pounds of Kryocide per acre (T5), had significantly higher amounts of fluoride in the wine than any other treatment.