WINTER 2023 APPLE POST FREEZE REPORT
Willick IR (2023) WINTER 2023 APPLE POST FREEZE REPORT. https://www.perennia.ca/wp-content/uploads/2023/06/Post-freeze-report-Ian-WIllick_2023-05-31.pdf
Plain language summary
This report highlights the influence of the February 3-4 2023 freezing event on the winter hardiness of apple buds. Bud and woody stems of commercially available apple cultivars were collected before and after the freezing event. Gala, Honeycrisp and Ambrosia buds were not injured by the freezing event. Subsequent visual observations of less hardy cultivars such as Gravenstein were more susceptible to injury. The lethal temperature at which half the buds were injured was also assessed using a lab based assay. Trees that are nutrient deficient could be more prone to freezing injury. The report also discussed potential issues that growers may experience in the Spring as a result of a freezing event.
Freezing events: On February 3 and 4, night temperatures dropped to -25°C and -27°C. This was the
coldest widespread temperatures observed in Nova Scotia since 2009. A second freezing event occurred
on February 27th where nighttime temperatures ranged from -17°C to -25°C. Warm winter temperatures left trees more susceptible to injury: The average December and January temperatures were the warmest recorded since 1914. Despite this issue, buds from the three tested varieties were undamaged following the freezing events. Visual observations in less hardy cultivars such as Gravenstein suggest that more susceptible varieties may experience injury to the king bud or complete bud loss due to vascular collapse in the Spring. Potential issues heading into the growing season: Apple trees will likely be weaker going into the growing season. Check on blocks with known nutritional deficiencies such as dull leaves in the spring. We may see site- and block-specific vascular collapse in tender varieties. Weak trees will also be more susceptible to insect and disease pressure.