Hardiness has been measured in fall and winter in two consecutive years. Measurements in April were limited by a lack of sufficient shoots, but were measured in a smaller number of rootstocks in 2013. Injury was measured in both 1- and 2-year-old shoots and was found to differ somewhat with age, so the results are focused on 2-year-old shoots since rootstocks influence the hardiness of older wood. Injury was also measured in bark, cambium and lateral buds, but these results are not presented in thisreport since injury to the wood is closely associated with tree performance. Lethal temperature was based on 10% to 20% of the wood being discolored.
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