@article {Williams283, author = {D. W. Williams and H. L. Andris and R. H. Beede and D. A. Luvisi and M. V. K. Norton and L. E. Williams}, title = {Validation of a Model for the Growth and Development of the Thompson Seedless Grapevine. II. Phenology}, volume = {36}, number = {4}, pages = {283--289}, year = {1985}, doi = {10.5344/ajev.1985.36.4.283}, publisher = {American Journal of Enology and Viticulture}, abstract = {This study compares the prediction of phenology models for the grapevine cultivar Thompson Seedless that are based on degree days ({\textdegree}D above 10{\textdegree}C) with patterns observed in the field. Budbreak, bloom, and the development of total soluble solids were monitored in six vineyards over a latitudinal range of 300 km in the San Joaquin Valley of California in 1983. The models predicted dates of 50\% budbreak and 50\% bloom within a few days of the observed events. Relative calendar timing followed the expected latitudinal trends, with earliest budbreak and bloom dates observed at the southernmost sites. The model predicted maturity (20{\textdegree} to 21.5{\textdegree}Brix) reasonably at four vineyards and underestimated it at the other two, one of which had vines that were water stressed and lightly cropped relative to the others. Predictions of {\textdegree}Brix differed substantially from observations in the range 14{\textdegree} to 18{\textdegree} at most sites. The factors influencing vine phenology, including temperature, solar radiation, water availability, and vine management practices, are discussed.}, issn = {0002-9254}, URL = {https://www.ajevonline.org/content/36/4/283}, eprint = {https://www.ajevonline.org/content/36/4/283.full.pdf}, journal = {American Journal of Enology and Viticulture} }