August. 



Trees consisting of four parts denoted as "C" series inter- 

 stem dwarf apple trees are available from a nursery in Mis- 

 souri. These have a seedling root, K-14 winter hardy trunk, 

 a dwarfing interstem (C-6 or C-52) and the fourth part of 

 this tree is the desired cultivar (Fig. 2B). The nursery reports 

 that standard cultivars with C-6 produce trees about half size 

 of standards on seedling roots. The interstem C-52 produces 

 trees about two-thirds to three-quarters the size of the cul- 

 tivar on seedling roots. Combining the spur-type cultivars 

 with the C-6 and C-52 interstems reportedly produces earlier 

 bearing, heavier yielding, and smaller trees than if standard 

 type cultivars are used. Our experience with the "C" series 

 in Massachusetts is limited. 



There is an active interest in interstem trees with M.9 

 interpiece because of the desire for small trees that do not 

 require support. Tree size should be intermediate between 

 that produced by M.9 and M.7 rootstocks. It is suggested 

 that the M.9 interstem should be at least 6 inches long and 

 positioned on the stem of the understock at least 12 inches 

 from the top of the roots to permit deeper planting. 



Interstem trees are suggested for trial. 



Orchard Design 



Tree density defined. Terminology and planting distances 

 used vary among researchers with compact apple trees. Below 

 is shown the names we have chosen for this publication, the 

 tree number in each density, and the rootstock and interstem 

 combinations that can be utilized in each density. 



Rootstock and interstem 

 combinations that can be 

 Density Number of trees/A utilized in each density^ 



Low Less than 1 14 



Medium 115 to 249 



High 250 or more 



Seedling, MM 111, MM 106, 

 Alnarp2, M.13, C-52/K-14/ 

 seedling, M.7. 



MM 106, M.7,C-52/K-14/ 

 seedling, C-6/K-14/seedling, 

 M.9/seedling, M.9/Alnarp 2, 

 M.9/MM 111,M.9/MM 106, 

 M.26. 



M.9 



Cultivar vigor and soil type are factors influencing tree 

 spacing. 



Tree spacing. We cannot make firm recommendations on 

 planting distances because our experience is too limited. 

 Furthermore, the number of variables affecting tree size 

 are great— orchard site, soil, severity of pruning, nutrition 

 and tree training among others. However, as a guide we have 

 suggested in Table 11, planting distances that seem reason- 

 able minimum spacings for our conditions in Massachusetts. 

 Similar tree spacings are given for both medium and low 

 vigor cultivars which reflects our lack of experience with the 

 spacing requirements of various cultivar-rootstock combina- 



Fig. 2. Interstem trees. (A) is a3-piece tree with an MM 106 

 understock, M.9 interstem, and Mcintosh as the 

 cultivar. (B) is a 4-piece tree with a seedling under- 

 stock, K-14 winter-hardy trunk, C-6 dwarfing inter- 

 stem, and Mcintosh as the cultivar. 



tions. However, we have 20 years of commercial experience 

 with M.7 and strongly believe that without restrictive prun- 

 ing, 16 ft. X 24 ft. should be considered the minimum spacing 

 of a permanent planting of vigorous cultivars on this root- 

 stock and that on some soils 20 ft. x 30 ft. spacing is not 

 too wide. 



We have allotted an 8 ft. alley for orchard travel and har- 

 vest operations. If you like a 7 ft. alley, decrease the spacings 

 between the rows by I ft. (for example, a 16 ft. x 24 ft. spac- 

 ing to 16 ft. x 23 ft.). 



It cannot be overemphasized that as planting density 

 increases, it becomes even more important that soil, cultivar 

 and rootstock be correctly matched. When deciding on what 

 density to plant, consider the following factors: (1) the 

 characteristics of the site and soil— windy, poorly drained 

 soil, etc.; (2) cultivar being planted— vigorous, spur-type, etc.; 

 (3) time available for tree training and pruning; and (4) meth- 

 od of marketing— "pick-yourown," processing, or fresh use. 



Low density tree planting. Usually allows for full tree devel- 

 opment with a minimum of pruning to restrict tree spread. 

 It requires the least investment per acre while production 

 costs are below those of orchards on seedling rootstock. 

 Massachusetts growers should consider low density plant- 

 ings when the cultivar is a vigorous-growing (Mcintosh and 

 Delicious) standard-type tree and the rootstock is M.7 or 

 MM 106 because it is difficult to restrict the size of these 

 trees. Plantings of these cultivars on these rootstocks spaced 

 10x18 feet, 15 x 20 feet, or 20 x 20 feet have become so 

 dense that growers have been forced to remove trees while 

 the orchards were still relatively young. 



Medium density tree planting. Thisdensity will require more 

 careful attention to training and pruning trees than with low 

 density planting to prevent tree crowding and maintain fruit 

 quality. It is essential to maintain conical-shaped trees 



11 



