•14- 



The yield reduction on the height- reduced trees was 

 not consistent until 1978 (Table 1). In 1978 and 1979 the 

 shorter trees of both cultivars produced less fruit than the 

 taller trees. The 2.5 foot reduction in tree height reduced 

 yield by 2.5 to 3 bushels in 1979. This is a sizeable re- 

 duction in yield and should be considered when reducing 

 tree height in an established planting. New plantings can 

 be designed with higher tree densities to compensate for 

 bearing surface lost by keeping trees shorter. 



Table 1. Influence on yield from height reduction of 

 Spartan and Idared treesz. 



Spartan^ Idared 



X 



Height Height 



Year reduced Control reduced Control 



Bushels/tree 



1976 6.0^ 8.0a 6.2a 7.5a 



1977 4.0b 5.3a 4.1a 4.8a 



1978 10.4b 12.5a 10.2b 12.4a 



1979 9.6b 12.9a 8.9a 11.4a 



z 

 Trees planted in 1964; trial started in Feb., 1976. 



y 



Tree height 3/79: Control - 11.4'; height- reduced trees: 

 8.9' 



X 



Tree height 3/79: Control - 10.6'; height-reduced trees: 

 8.3' 

 w 

 Means in any row for each cultivar followed by different 

 letters are significantly different at odds of 19 to 1. 



Summary 



We plan to maintain the 2.5 foot height difference be- 

 tween the height-restricted and height-reduced trees in 1980 

 and 1981 in order to determine the yield differences. It is 

 unfortunate that Mcintosh trees are not in this trial because 

 it would be of interest to determine the effect of pruning on 

 fruit color. Nevertheless, this trial and others has supplied 

 valuable information on containment pruning, and should continue 

 to do so. Trees on vigorous-size controlling rootstock are the 

 predominant type tree in Massachusetts. We believe that by main- 

 taining a dominant central leader and doing containment pruning, 

 trees on M7, MMlll, and MM106 can be kept to a size suitable 

 for medium density orchards (115-200 trees per acre). 



