Effects of Rootstock and Interstock on the Growth, 

 Productivity, and Anchorage of a Spur and Standard 

 Strain of Delicious 



Wesley R. Autio and Franklin W. Southwick 



Department of Plant & Soil Sciences, University of Massachusetts 



A number of studies have compared spur and standard 

 apple strains but commonly have not assessed the addi- 

 tional effects of rootstock and interstock. In this study we 

 compared the effects of M.7A, M.26, M.9/MM.111, M.9/ 

 MM. 106, and MM.lll on the growth, productivity, and 

 anchorage of Starkrimson Delicious (spur strain) and 

 Gardiner Delicious (standard strain) trees. 



Trees were planted in the spring of 1981 at the Horti- 

 cultural Research Center, Belchertown, MA. The experi- 

 mental design was a randomized complete block with 7 

 replications. Within each block 4 trees were planted per 

 strain-rootstock-interstock combination, and the two 

 middle trees were used for data collection. All rows were 

 20 ft apart, but spacing within rows varied with the combi- 

 nation. Starkrimson trees on M.26, M.9/MM.106, and 

 M.9/MM.111 were spaced 12 ft apart, and Starkrimson 

 trees on M.7A and MM.lll and Gardiner trees on M.26, 

 M.9/MM.106, and M.9/MM.111 were spaced 14 ft apart. 

 Gardiner trees on M.7A and MM.lll were spaced 16 ft 

 apart. 



In 1983 bloom was assessed, and in 1984 bloom, fruit 

 set, and yield were measured. In 1985 tree height, spread, 

 trunk circumference, and yield were measured. The 1985 

 tree spread values were used to calculate theoretical tree 



spacings and theoretical numbers of trees per acre. It was 

 assumed that the optimal distance between trees within a 

 row should be 50% greater than the 1985 tree spread and 

 the distance between rows should be 8 ft greater than the 

 distance between trees within a row. The value of 50% was 

 used because it resulted in approximately the accepted 

 densities for the 2 strains on M.7A, the most tested root- 

 stock in the study. These values were used to calculate the 

 theoretical yield per acre in 1984 and 1985. 



In September, 1985 these trees experienced the effects 

 of Hurricane Gloria, which allowed an assessment of tree 

 anchorage of these strains on the various combinations. 

 The angle of lean from the vertical was used to measure 

 anchorage, since poorly anchored trees were partially or 

 completely blown over. 



Tree Size 



Tree height, spread, and trunk circumference, ob- 

 tained in November, 1985, are presented in Table 1. For 

 each measurement Gardiner trees were significantly larger 

 than Starkrimson trees. This relationship between a spur 

 and a standard strain has been shown many times. Signifi- 

 cant differences also existed among rootstocks within each 



