Levels of Cryolite on Thompson Seedless Grapes and Raisins

¹ Department of Environmental Toxicology, University of California, Davis, California 95616.

Cryolite (sodium aluminofluoride, Na₃AlF₆) was applied to Thompson Seedless grapes at various rates and in various formulations for control of the omnivorous leaf roller. Grapes given a single application of cryolite had acceptable residue levels 30 days after application (4.9 and 5.1 ppm). When the same formulation was applied on two separate dates, June 3 and July 21, initial residues on the grapes were much greater but residues 30 days later were about the same (5.9 ppm). Late applications, however, especially two applications, resulted in unacceptably high residues on washed, dried, and sorted raisins produced from the grapes (> 7.0 ppm).