Cold hardiness is the ability of a plant to withstand low temperatures. Low temperature injury after a pruning cut can vary depending on when the low temperatures occurs (early vs. mid- or late-winter), how fast the temperature drops after the pruning cut, what the temperatures are the few days before and within 10-14 days after the pruning event, and how long the low temperatures are sustained in the orchard. Young trees are more sensitive to cold snaps after pruning than older trees. For those of you who produce fresh fruit we recommend you start pruning your older trees and the most resistant cultivars to winter damage first. The most resistant cultivars like McIntosh should be pruned now leaving the more sensitive cultivars until after January 1. Do not start your pruning of Empire, Red Delicious, Golden Delicious, Jonagold, and Mutsu at this time of the year just because you have the time and/or available labor force. Cutting done at this time (particularly making large chainsaw cuts) can predispose trees to winter injury if temperatures drop rapidly in the next couple of weeks. Hold off all pruning of most sensitive cultivars until trees have time to harden off under more cold weather. The more sensitive apple cultivars to winter damage after a pruning cut are: Golden Delicious, Red Delicious (more sensitive), Empire (more sensitive), Jonagold, and Mutsu. The apple cultivars with an intermediate susceptibility to winter damage after a pruning cut are: Paula Red, Cortland, Gala, Idared, and Greenings. The apple cultivars with less sensitive to winter damage after a pruning cut are: Honeycrisp and McIntosh (all strains).

Managing Crop Load of Apple Orchards by Pruning (pdf; 265KB)