Performance of 'Gala' apple on four semi-dwarf rootstocks: A ten-year summary of the 1994 NC-140 semi-dwarf rootstock trial

In 1994, trees of 'Gala' apple (Malus x domestica Borkh.) on 4 semi-dwarf rootstocks were planted at 20 locations in North America according to the guidelines established for cooperative testing by the North Central Regional Cooperative Project (NC-140). The four rootstocks were P.1, V.2, G.30, and M.26 EMLA. Four of the locations did not receive trees on P.1 rootstock. Tree losses were greatest for G.30. Trunk cross-sectional area (TCSA) was generally largest for P.1 and smallest for G.30. TCSA was most variable for M.26; at some sites, trees on G.30 had larger trunks than trees on M.26. Tree height was usually greatest for P. 1 and tree spread was usually smallest for M.26 EMLA. Although results were not consistent for all sites, yield and yield efficiency tended to be highest for G.30 and lowest for P.1. Although the effect of rootstock was not consistent, cumulative yield efficiency tended to be lower for G.30 than for M.26 or V.2. Trees on P.1 and G.30 produced the most root suckers.