Hardiness of Apple and Peach Trees in the NC-140 Rootstock Trials

Abstract

Artificial freezing tests were conducted to determine the effect of rootstocks on scion hardiness. ‘Starkspur Supreme Delicious’ scion wood was obtained from M.7 EMLA, M.9 EMLA, M.26 EMLA, MAC 9, and OAR 1 trees in the 1981 NC-140 rootstock trial located at New Franklin, Missouri on 8 Dec. 1986. ‘Red-haven’ scion wood from the 1984 NC-140 peach planting was collected on 14 Jan. and 2 Mar. 1987. Peach rootstocks evaluated in freezing tests included Bailey, Damas 1869, GF 655-2, GF 677, Halford, Lovell, Siberian C, and own-rooted ‘Redhaven.’ Overall, phloem and xylem of MAC 9 trees were more susceptible to winter injury than all other rootstocks except OAR 1 when injury ratings were averaged across a range of low temperatures. Cambial mortality was observed at −32.6°C in MAC 9 trees where as mortality in M.7 EMLA trees occurred at −35.8°C. GF 655-2 suffered greater phloem injury than Bailey, GF 677, and own-rooted ‘Redhaven’ trees at −31°C in Dec. However, xylem tissue of Bailey, GF 655-2, and GF 677 exhibited greater injury than that of Damas 1869 and Lovell at −31°C in Dec. Peach rootstocks did not differ in flower bud hardiness in Jan., but Lovell was more cold resistant than all other rootstocks except Damas 1869 in Mar.