2019/2020 Nova Scotia Wine Grape Bud Hardiness Report no. 4: December 18 – 19

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. All varieties in our survey have continued to deepen their acclimation values. The two hybrid varieties in the survey, L’Acadie Blanc and Marquette, have shown the greatest change in acclimation values with a drop of approximately 3 °C since the previous survey. The three Vitis vinifera varieties all have very similar acclimation values at this point with a change of only 1 °C since the last survey. Figure 1 shows this relationship with the bud hardiness values for Chardonnay, Pinot Noir and Riesling being almost identical. Last year at this time all varieties showed bud hardiness values approximately 1 °C lower than this year. This is likely due to the warmer than average temperatures experienced in December. On average, the first three weeks of December 2019 were 2 °C warmer than the same period in 2018.