Grape phenology and GDD accumulation August 16, 2021 by Marilyn Odneal GDD base 50 = 2317. 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 Chambourcin is coloring up more and the white cultivars are getting close to harvest. Chambourcin is showing more color and is being netted this week.