Volume 10 Issue 2
February 12, 2021
For several years, the WA Blueberry Commission has funded WSU research to collect bud hardiness data and create a model. Our research team is still in the process of developing the model but we do collect, freeze, and cut buds to assess mortality of individ-ual flower initials. Below is the data for lethal temperatures. Important considerations when looking at the numbers are:
Date assessed and stage: If your buds have progressed in development since our date of assessment, the buds will be less cold hardy.
Location: Preceding and local temperatures are influential in the level of cold hardiness. Warmer sites will likely be less cold hardy with possibly more advanced buds.LT10oF: This is the Lethal Temperature in which 10% of the floral initials will die. This can vary by cultivar, site, temperatures, and stage.
Date assessed | Location | Cultivar | Stage | LT10oF |
2-Feb-21 | Whatcom Co. | Aurora | dormant | -5 |
2-Feb-21 | Whatcom Co. | Draper | dormant | 3 |
2-Feb-21 | Skagit Co. | Aurora | dormant | -2 |
2-Feb-21 | Skagit Co. | Draper | dormant | 7 |
8-Feb-21 | Prosser | Aurora | dormant and early bud swell | -2 |
8-Feb-21 | Prosser | Draper | dormant and early bud swell | -0.4 |
8-Feb-21 | Prosser | Duke | dormant and early bud swell | -4 |
8-Feb-21 | Paterson | Aurora | dormant and early bud swell | -2 |
8-Feb-21 | Paterson | Draper | dormant and early bud swell | -4 |
4-Feb-21 | North Prosser | Aurora | dormant and early bud swell | -9 |
4-Feb-21 | North Prosser | Draper | dormant and early bud swell | -2 |
Please note that in all prior years of studying cold hardiness, we have seen buds at bud swell reacclimate to cold weather within 24 hours. The 3 cultivars here are all highbush blueberries. Other cultivars with more southern highbush in the germplasm (e.g. Legacy) will have lower hardiness. |
For more information:
AgWeatherNet (http://weather.wsu.edu/) has grape and cherry cold hardiness models. Log on and go to crop models.
Blueberry concerns:
Eastern WA, Gwen Hoheisel (ghoheisel@wsu.edu) Western WA, Lisa DeVetter, Lisa Wasko (lisa.devetter@wsu.edu)
Michigan Cold Hardiness Bud Chart (https://www.canr.msu.edu/blueberries/growing_blueberries/growth-stages)