2018/2019 Nova Scotia Wine Grape Bud Hardiness Report no. 7: January 21 - 22

A wine grape bud hardiness report is generated and distributed to the Grape Growers of Nova Scotia (GGANS) membership on a bi-weekly basis throughout the dormant season. The bi-weekly survey is performed on 3 vinifera cultivars (‘Chardonnay’, ‘Riesling’, ‘Pinot Noir’) and 2 hybrid cultivars (‘L’Acadie Blanc’, ‘Marquette’) and involves 10 grower collaborators for a total of 23 varietal blocks in total. Each report uses a table to show the latest low temperature exotherm (LTE) levels for the present and past weeks. The report also includes comments highlighting observations over the last reporting period, a plot showing the change in LTE values throughout the season, the historical 100 year minimum values and the present year’s minimum values. Three times throughout the season (early, middle, late) 11 “extra” varieties (‘Baco Noir’, ‘Chenin Blanc’, ‘Geisenheim’, ‘Leon Millot’, ‘Lucie Kuhlman’, ‘New York Muscat’, ‘Pinot Gris’, ‘Sauvignon Blanc’, ‘Seyval Blanc’, ‘Seyval Blanc’, ‘Vidal Blanc’, ‘Ortega’) from 22 additional varietal blocks are also reported.

Temperatures have been in a constant cycle since late December with temperature swings from well above freezing to minus double digits every few days. Although temperature cycling was also a feature of last year’s weather, it has been much more pronounced this year. One impact of this has been that grape buds are slightly less acclimated than they were at this time last year. The difference between this year and 2017/18 ranges from approximately 0.5 °C for Chardonnay to almost 2 °C for Riesling. In spite of this, there is a 5 to 10 degree separation between the daily low temperatures and the LTE50 of the most tender varieties in our survey. In addition, all of the LTE10 values are below -20 °C as can be seen in the table below.