GDD base 50 = 93-183. We track GDD at http://agebb.missouri.edu/weather/reports/gddTable.asp and rate the phenology stages according to the Modified E-L System http://door.uwex.edu/files/2010/10/ModifiedEichhornLorennzsystem.pdf
At this point, there are few primaries on many cultivars. Norton in the North and Foundation vineyard have some primary growth. NC-6 which develops later has the most primaries of all cultivars on the station and may have a 75% percent crop. The Catawba crop is lost. The crop overall, at this point, is very significantly reduced.