Grape Variety Developmental Stages: July 5, 2019
At the West Madison Agricultural Research Station (WMARS) in Madison, WI, shoot development across most cultivars’ buds were in E-L* stage 27 (“Setting; young berries enlarging (>2mm diameter), bunch at right angles to stem”) through E-L stage 31 (“Berries pea-size (7 mm diameter)”). Currently, vines are behind in development compared to 2017 and 2018 seasons due to the cooler spring. At the Peninsular Agricultural Research Station (PARS), all varieties are at E-L stages 21 (“30% caps off”) through 25 (“80% caps off”).
The following photos were taken on July 1, at West Madison Agricultural Research Station.
Brianna berries pea size, 7mm diameter
E-L 31
Crimson Pearl berries pea size, 7 mm diameter
E-L 30
Frontenac berries pepper corn size, 4 mm diameter E-L 29 
Itasca berries pepper corn size, 4 mm diameter E-L 29 
La Crescent berries pea size 7 mm diameter
E-L 31
Marquette berries pea size, 7 mm diameter
E-L 31
Petite Pearl berries pepper corn size, 4 mm diameter, E-L 29
The following photos were taken on July 2, 2019 at The Peninsula Agricultural Research Station. Everything is E-L 21-24, flower caps falling off and flowering.
Brianna 
Frontenac 
LaCrescent 
LaCrosse 
Marquette 
St. Croix
*E-L stands for Eichhorn-Lorenz Phenological stages to describe grapevine development
April 1-July 5, 2019 Growing Degree Days (Base 50°F)
| 2019 | 2018 | 2017 | |
| WMARS | 900 | 1183 | 967 |
| PARS | 513 | 750 | 602 |
Growing degree-day accumulation from April 1 to July 5 for the past three seasons. Currently, the 2019 season is running behind in GDD accumulation compared to 2017 and 2018 seasons. Degree-days were calculated using a base 50°F, starting on April 1 as a biofix. We calculated degree days using the NEWA website, and you can visit their “About degree days” page to learn more about the degree days and the formulas used for their respective calculations.
This article was posted in Grapes and tagged grape phenology.