In late Oct., most genotypes did not have significant discoloration until a temperature of -25 to -30 °C. G.935, G.3902 and G.4011 had the least amount of xylem injury at the coldest temperature, -35 °C, with a discoloration rating of 2.0 or lower. G.4013, G.4814 and G.5087 had a similarly low level of injury, but a maximum rating that was greater than 2.0. The greatest injury occurred in G.41 and G.214, and these had a rating greater than 7.0. G.30, V5, V6 and V7 had maximum levels of browning at -35 °C in the range of 5.0 to 7.0, and were not significantly different from G.41. Intermediate browning occurred in M.9, B.9, G.4292, G.4814 and G.5257.
In mid Nov., G.935, G.4011, G.5087 had very little injury at -35 °C and a maximum rating of 2 or lower. M.9, B.9, G.214, G.3902, G.4013, V5 and V6 also had less injury than the most tender genotypes, but a maximum rating greater than 2.0. The greatest level of injury occurred in G.30, G.41, G.4292, G.4814, G.5257 and V.7 with a maximum injury rating greater than 5.0, although in G.4814 and G.5257, injury was minimal below -35 °C.