Performance of ‘Starkspur Supreme Delicious’ on 9 Rootstocks at 27 Sites Over 10 Years

Abstract

In 1980-1981, ‘Starkspur Supreme Delicious’ trees on 9 rootstocks were planted at 27 sites in the United States and Canada according to guidelines established for cooperative testing by the NC-140 technical committee. Over the years, 7 plantings were removed because of excessive tree loss due to voles (NY), winter injury (MN, MT), or other factors (CO, MO, NC, SC). The following sites averaged less than 10% tree loss over the 10 years of the study: MA, OR, ONT, WA, WI and PA. Trees on M.7 EMLA survived well at all sites. IA lost all trees on MAC.24 to winter injury, while 8 sites had no losses with this rootstock. Based on trunk cross-sectional area (TCA), trees at the following sites were the largest: GA, IL, IN, ONT, CA and VA and smallest in WA, MA and QUE. Height of trees on M.26 EMLA and O.3 varied more than other rootstocks of comparable size (M.9 EMLA, M.9 and MAC.9). CA averaged much higher yield efficiencies than the other sites, because of high yield efficiencies on MAC.24, M.7 EMLA and OAR 1. Tree size in MA was small, but yields were high. Generally, trees in CA and MA had high production efficiencies as measured by yield/TCA. Production efficiencies were lowest in AR, IA and QUE. In addition to CA and MA, O.3 was very efficient in OR, ONT and WI.