GDD base 50 = 853. We track GDD at http://agebb.missouri.edu/weather/reports/gddTable.asp and rate the phenology stages according to the Modified E-L at stages according to the Modified E-L System https://door.extension.wisc.edu/files/2010/10/ModifiedEichhornLorennzsystem.pdf   Photos to follow... … [Read more...] about Grape Phenology and GDD accumulation