RT Journal Article SR Electronic T1 Persistence of Elemental Sulfur Spray Residue on Grapes during Ripening and Vinification JF American Journal of Enology and Viticulture JO Am. J. Enol. Vitic. FD American Society for Enology and Viticulture SP ajev.2014.14027 DO 10.5344/ajev.2014.14027 A1 Kwasniewski, Misha T. A1 Sacks, Gavin L. A1 Wilcox, Wayne F. YR 2014 UL http://www.ajevonline.org/content/early/2014/08/13/ajev.2014.14027.abstract AB Elemental sulfur (S0) is commonly used to control powdery mildew in vineyards, but S0 residues in musts have been correlated with increased H2S and sulfurous off-aroma formation during fermentation. As a consequence, S0 is often used sparingly late in the season, but defining appropriate pre-harvest intervals for S0 sprays has been challenging due to limited data on S0 persistence in vineyard s and during pre-fermentation operations. Utilizing a new quantification method, S0 residues were monitored in the vineyard over 3 years of field studies. Treatments varied in commercial formulation, application rate, and timing of the last application before harvest, all of which affected S 0 concentrations on the fruit at harvest. Residue levels generally were lower for a wettable powder versus a micronized formulation applied at the same rate and timing, and increased proportionally to the application rate when timing and formulation were constant. In all years, ceasing application ≥35 days prior to harvest resulted in S0 residues below the 10 μg/g concentration associated with increased H2S production in several previous studies. S0 residues >1 μg/g correlated with increased H2S production in our current work and were observed on all fruit sprayed within 56 days of harvest. However, clarification decreased S0 in must by >95% prior to fermentation in all treatments. Furthermore, fermentation on treated skins increased H2S formation nearly 3-fold relative to fermentations without skin contact. Collectively, these results indicate that S0 residues are likely of low concern in white winemaking whereas residue levels in red fermentations can exceed levels associated with increased H2S production when some S0 sprays are applied within 8 weeks of harvest.