We usually begin grape phenology on April 1st, but since development is a bit early this year, we began earlier. GDD base 50 accumulation count begins April 1 in this resource. We will calculate the March data by hand and add it to our April 1 count  http://agebb.missouri.edu/weather/reports/gddTable.asp Phenology stages according to the Modified E-L system … [Read more...] about Grape phenology and GDD accumulation