Early 



Table 10. Summary of rootstock characteristics 

 (Letters A-E denote estimate of value: A = excellent; E = poor) 



Collar Rot 



Tolerance to: 



Remarks and 



bearing Productivity Anchorage Resistance Wet soil Dryness Low T° Recommendations 



Highly vigorous-90 to 100% standard 



Use now limited. 

 Does well on wet soils. 

 Tolerates heavy soils. 



Very susceptible to collarrot. 



Never very popular. 



Avoid poorly drained soils. 



Suckers. 



Popular with M.9 interstem. 



Inadequately tested in U.S.A. 



Inadequately tested in U.SA. 



Attractive to mice. 



Fire blight susceptibility. 



VReported as not being hardy where there are mild periods during winter because it has a very short rest period. 



Trees on M.7 need to be budded 8 to 10 inches high in 

 the nursery so that the trees can be planted deeper in the 

 orchard. Deeper planting provides better anchorage and 

 reduces suckering. M.7 produces a tap root, thus trees on 

 this rootstock should be planted on deep, well-drained soils. 

 In spite of higher budding, providing temporary basal sup- 

 port by means of 3-foot long hardwood stakes driven 2 feet 

 into the ground is advisable for Red Delicious and for all 

 cultivars on windy sites. 



MM 106 has some good characteristics and some believe 

 these outweigh its weaknesses when budded on semi- 

 vigorous cultivars (Idared, Empire, or spur-types) and plant- 

 ed on light loam soils. Trees on this rootstock come into 

 production early. MM 106 also has a strong well-balanced 

 root system, therefore, anchorage is not a problem. It is 

 sucker-free and resistant to wooly aphids. 



Our Massachusetts orchards frequently have localized 

 wet areas and in these areas we lose trees on MM 106. 

 Furthermore, MM 106 produces large trees with such cul- 

 tivars as Mcintosh. Loss of trees on MM 106 is commonly 

 attributed to collar rot but may be more directly related to 

 winter injury at the crown, soil management, or soil drain- 

 age. (Trees on MM 106 are slow to mature in the fall and 

 the trunk tissue near ground level, which is the MM 106 

 portion of the tree, is late maturing and thus more suscep- 

 tible to low temperatures in early winter than the other 

 above-ground portions of the tree.) 



MM 111. A good rootstock for sandy loam soils because it is 



more drought-tolerant than other size-control rootstocks. 

 It is more vigorous than MM 106, thus it is of no value to 

 orchardists desiring to increase tree numbers per acre. Cur- 

 rently, MM 1 1 1 is being used as the understock for interstem 

 trees because it produces well anchored trees. It is inter- 

 mediate in winter hardiness. 



Seedling. These formerly constituted the bulk of the root- 

 stock material used for apple trees. No two seedling root- 

 stocks are identical in genetic makeup. Trees on seedling 

 rootstocks are well-anchored and more tolerant to unfavor- 

 able soil conditions than many M. and MM rootstocks. Trees 

 on seedling rootstocks are slower to come into production 

 than those on size-control rootstocks. Seedling rootstocks 

 will produce trees 25 to 30 feet or more in height without 

 restrictive pruning. Trees on seedling roots are inefficient 

 because tree centers are unproductive or produce poor qual- 

 ity fruit due to inadequate sunlight. Presently, seedlings are 

 used mainly as the understock for spur-type trees and inter- 

 stem trees. 



Interstem Trees 



The interstem tree ordinarily consists of: the understock, the 

 interstem, and the scion variety (Fig. 2A). Interstem trees 

 cost more, and they are usually only available by contracting 

 two years in advance. The scheme most often practiced by 

 the nurseryman is to bench-graft the interstem (M.9) onto 

 the chosen rootstock (usually MM 106 or MM 111), plant 

 this tree in the nursery and bud on to it the scion variety in 



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