12- 



Results Through Harvest of 1982 and Conclusions 



Containment pruning to restrict tree height continued to 

 be successful. The height difference (measured at top of 

 central leaderj between the control Spartan and Idared trees 

 and the height-restricted trees of these varieties now averages 

 4.0 and 3.7 feet, respectively. Although the influence of 

 height restriction on yield still is not consistent (Table 1) , 

 the cumulative yields for the 7 years have been 12 bushels 

 less per tree on the height-restricted trees. 



The harvest crew has expressed its preference for the 

 height-restricted trees but the yield reduction may be unaccept- 

 able to most growers. Theoretically, yields per acre of the 

 height-restricted and control trees would be similar if the 

 shorter trees were spaced 20% closer. For example, the trees 

 in this trial are spaced 20 feet x 30 feet (72 trees/acre) . To 

 increase tree numbers by 20% (86 trees/acre) one would plant 

 the trees at 18 x 28 foot spacing. 



Containment pruning will work on many varieties but certain 

 varieties are much more vegetative than others. We have en- 

 countered no difficulty in maintaining the Idared and Spartan 

 trees on M7 at 8.3 feet and 9 feet, respectively. However, tree 

 height of 9 feet is too low for the innate vigor of non-spur 

 Delicious on M7 at our Horticultural Research Center. In con- 

 trast, spur-type trees of Delicious on M7a could be easily 

 maintained at 9 feet (height of central leaders) . 



Procedures Suggested to Contain Tree Size 



1. Branches that crowd those of adjacent trees will have to be 

 removed or cut back to a weaker side branch. (Cuts made 

 only to maintain the desired outer profile of the tree com- 

 pounds rather than alleviates tree containment problems. 

 Such cuts stimulate vigorous growth and by the end of the 

 next growing season, the limb may extend as far as the 

 original branch did before shortening, and may cause more 

 shading within the tree than did the original uncut branch.) 



2. Maintain conical tree shape by removing large limbs in the 

 top third of the tree or cutting them back to a very much 

 weaker side branch. 



3. Initiate a limb rotation program in the top third of the 

 tree by retaining weak branches or spreading desirable water 

 sprouts, which in turn may have to be removed when they be- 

 come too large. 



4. Reduce the height of excessively tall trees by cutting them 

 back to a strong outward growing lateral branch originating 

 at a lower level on the leader. 



