Orchard performance of Redhaven grafted on several interspecific hybrid <i>Prunus</i> rootstocks in comparison to Bailey seedling rootstock in Southern Ontario

A 9-year orchard experiment was established to measure the performance of Rootpac®-R, Rootpac®-20, Rootpac®-40, and Rootpac®-70 rootstocks using Redhaven peach ( Prunus persica var. persica) as the scion, compared with Bailey, the current industry standard. Tree survival after 5 years was only 38% on Rootpac®-40, and the remaining rootstocks showed little or no tree mortality. Tree vigour and canopy height and width were influenced by rootstock genotype beginning the year of planting in 2016. Based on trunk cross-sectional area, after 9 years of production, Rootpac®-70 produced the largest trees followed by Rootpac®-40 and Rootpac®-R. Bailey and Rootpac®-20 had the lowest tree vigour. By year nine, cumulative yields were greatest on Rootpac®-70, measuring 5% higher than Bailey; cumulative yields of Rootpac®-R, Rootpac®-20, and Rootpac®-40 were 91%, 89%, and 81% that of Bailey, respectively. Cumulative yield efficiency was significantly influenced by rootstock, with Bailey being the most yield efficient and Rootpac®-40 the least. Rootpac®-40 generally produced the largest fruit. Based on tree vigour, high mortality of Rootpac®-40, and high suckering on Rootpac®-40, all Rootpac rootstocks evaluated in this study seem to impart excessive vigour unsuitable for higher density systems and offer no obvious advantage over Bailey rootstock, the current commercial standard in Southern Ontario.