2019 ASHS Annual Conference

Newly released fire blight resistant apple rootstocks can aid in disease management and improve production sustainability. As part of the multistate NC-140 cooperative research project, an apple rootstock study was established at the Chilton Research and Extension Center near Clanton, Alabama in 2014 aiming to assess 14 newly developed fire blight resistant and size-controlling rootstocks. Low-chill ‘Aztec Fuji’ apple was the scion cultivar used. The following rootstocks were tested: B.10, G.11, G.202, G.214, G.30, G.41, G.935, G.969, M.26 EMLA, M.9-T337, V.1, V.5, V.6, and V.7. Trees are arranged in a RCBD with ten single tree replications and trained to the highly efficient Tall Spindle training system which has not been tested in Alabama before. Tall Spindle is designed to control the vegetative vigor and optimize the crop production especially in the early stage of tree establishment, while providing early returns to the grower. Our fifth-year results suggest trees grafted on ‘V.7’, ‘G.969’, and ’V.5’ produced the highest cumulative yield/tree. In general, the Vineland series of rootstocks ‘V.5’, ‘V.6’, and ‘V.7’ had high productivity, and were the most vigorously growing rootstocks in the present study based on data for trunk cross sectional area. Trees on ‘G.11’ consistently produced the largest mean fruit size ranging between 180 and 206 g through the seasons. ‘Aztec Fuji’ trees grafted on the weak ‘G.214’ rootstock had the highest yield efficiency of 1.18 kg/cm² at the end of the fifth season, while trees grafted on ‘V.6’ and ‘V.7’ rootstocks had the lowest efficiency of 0.54 and 0.60 kg/cm² respectively. Research is going to continue to assess the production efficiency and fruit quality as a way to achieve more efficient land use and sustainable apple production.