Scion and Rootstock Influence on Winter Survival of Peach Trees

Abstract

Survival ratings were made of 11 scion-rootstock combinations of 5-year old peach trees following a severe winter in which minimum air temperatures of −31°C were recorded. Tree survival was a function of scion cultivars and rootstock seed sources, but was affected more by the scion than the rootstock. Tree survival averaged over the four rootstocks was best for ‘Siberian C’ scions (95%), intermediate for ‘Harrow Blood’ scions (63%), and poorest for ‘Elberta’ scions (43%). The survival of ‘Elberta’ scions was significantly affected by rootstock seed sources with survival being best on seedlings of ‘Siberian C’ (67 %), intermediate on seedlings of ‘Bailey’ (32%), and poorest on seedlings of ‘Rutgers Red Leaf’ (18%).

Cold injury is an important limitation to peach culture in Canada and the Northern United States (2). Genetic differences in the cold hardiness of peach cultivars are a significant factor in tree survival (4, 6, 7). Recently, it has been shown that peach seedling rootstocks exert a modifying influence on the expression of scion hardiness (1, 4, 6), although the exact nature of this influence is not known (4). Rootstock seedlings of ‘Siberian C’ peach have been found to exert an enhancing influence on scion hardiness, more so than other peach seedling rootstocks studied (4). Peach seedling rootstocks have also been shown to affect tree survival indirectly through their effects on canker ( Leucostomaspp.) infection (3, 4, 5).

In an earlier study (6), we showed that cold acclimation of young peach trees was affected by temperature, photoperiod, cultivar and rootstock. The largest effects were associated with temperature and cultivar, while photoperiod and rootstock had smaller but detectable effects. At the completion of those studies the remaining trees of the various scion-rootstock combinations were planted outdoors at Cambridge, Ontario. Their survival of a test winter in 1975-76 forms the basis of this study.