The Influence of Rootstock and Strain on Growth and Production of ‘Delicious’ and ‘Golden Delicious’ Apple Trees1

The influence of 6 rootstocks on growth and productivity of spur and non-spur ‘Delicious’ and ‘Golden Delicious’ apple ( Malus domestica Borkh.) trees was investigated. The spur-type ‘Delicious strain (‘Miller Spur’) consistently produced more fruit per tree than the regular-type strain (‘Red Prince’). In contrast, standard ‘Golden Delicious’ produced as much or more per tree than the spur-type strain ‘Goldspur’ even in the early years. ‘Miller Spur Delicious’ trees were largest on seedling rootstock, intermediate on Mailing (M) 104, and smallest on M 111, M 106 and M 7. ‘Goldspur Golden Delicious’ resembled ‘Miller Spur Delicious’ in size, except that trees were significantly smaller on M 7 than on M 111 and M 106. At the end of the 9th season, ‘Red Prince Delicious’ and ‘Golden Delicious’ were largest on seedling, followed by M 111, M 106, M 7 and M 26 in descending order. Biennial bearing of some trees on all rootstocks reduced yield and increased tree-to-tree yield variance.