Grape Variety Developmental Stages: July 19, 2019
At the West Madison Agricultural Research Station (WMARS) in Madison, WI, shoot development across most cultivars’ buds were in E-L* stage 31 (“Berries pea-size; 7 mm diameter”) through E-L stage 33 (“Berries still hard and green”). 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 29 (“Berries peppercorn size; bunches tending downwards”) through 31 (“Berries pea-size; 7 mm diameter”).
The following photos were taken on July 15, at West Madison Agricultural Research Station.
Brianna E-L stage 33 Berries still hard and green 
Crimson Pearl E-L stage 33 Berries still hard and green 
Frontenac E-L stage 33 Berries still hard and green 
Itasca E-L stage 33 Berries still hard and green 
La Crescent E-L stage 33 Berries still hard and green 
Marquette E-L stage 33 Berries still hard and green 
Petite Peal E-L stage 33 Berries still hard and green
The following photos were taken on July 17, at Peninsular Agricultural Research Station.
St Croix E-L stage 29 
Marquette E-L stage 29 
LaCrosse E-L stage 29 
Frontenac E-L stage 30 
Brianna E-L stage 31 
LaCrescent E-L stage 30
Date April 1-July 19, 2019 Growing Degree Days (Base 50°F)
| 2019 | 2018 | 2017 | |
| Location: WMARS | 1257 | 1503 | 1261 |
| Location: PARS | 794 | 1020 | 860 |
Growing degree-day accumulation from April 1 to July 19 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.
*E-L stands for Eichhorn-Lorenz Phenological stages to describe grapevine development
This article was posted in Grapes and tagged Grapes.