Research and IPM

Phenology Model Database

Thompson Seedless Grapevine

Thompson Seedless

Phenology models predict timing of events in an organism's development. For many organisms which cannot internally regulate their own temperature, development is dependent on temperatures to which they are exposed in the environment.

Note: Before using a model that was not field tested in your location, you should test the model for one or more seasons under your conditions to verify that it will work for you.

Model 1 of 1

Williams, D.W., H.L. Andris, R.H. Beede, D.A. Luvisi, M.V.K. Norton, and L.E. Williams. 1985. Validation of a model for the growth and development of the Thompson Seedless grapevine. II. Phenology. Am. J. Enol. Vitic. 36:283-289.

Location of study: San Joaquin Valley (Ceres, Livingston, Biola, Parlier, Hanford, Shafter), California (field studies)

Developmental threshold

Lower:

50F

(10 °C)

Method of calculation: Double Triangle

Degree-day accumulations required for each stage of development

Biofix: February 20

	DD (°F)	DD (°C)
50% bud break	155.5	86.4
50% bud break to 50% bloom	741.4	411.9
Fruit maturity (20-21.5 brix)	2880-3240	1600-1800	(except Ceres)

Bud break is defined as the point at which green leaf tissue could first be seen between bud scales.