From Misha Kwasniewski’s PhD research . . . he uses a newly developed method to track the fate elemental S sprays on grapes during ripening, and during pre-fermentation processes. its well known that too much elemental S on grapes results in more H2S during fermentation. What Misha shows, in a nutshell, is that harvesting within a month of the last spray day date is risky for reds, but for whites good must clarification will solve most problems

http://www.ajevonline.org/content/early/2014/08/13/ajev.2014.14027.abstract?sid=cbe0f7c4-b745-4dfd-84c7-944cc652a2e8