The USDA system trees, in comparison to the slender spindle 

 trees, made less trunk circumference increase in 1976 and 1977 

 (Table 2) . In 1978 trunk circumference increase was similar for 

 the 4 pruning treatments probably because cropping restricted 

 vegetative growth on the slender spindle and regularly pruned trees 

 (Table 2). The influence of cropping on trunk circumference in- 

 crease also was evident in 1979. 



Table 2. The response of Spartan trees to pruning systems initiated 

 in 1976 at the Horticultural Research Center, Belchertown, MA^ . 



Year 

 response 

 measured 



Pruning system 



USDA 



Slender spindle 



Regular 



Tiers 



1976 

 1977 

 1978 



1976 

 1977 

 1978 

 1979 



Length of extension growth of central leader (cm) 



y 



103a- 

 98a 

 67a 



4.3b 

 4.3bc 

 5.0a 

 4.6a 



5.6a 

 5.0a 

 5.1a 

 3.9b 



Yield (bushels) 



1978 

 1979 



0.00b 

 0.32b 



0.12a 

 1.32a 



0.09a 

 1.02a 



0.02b 

 1.38a 



Trees planted in 1975. 

 r 



Means in rows not having letters in common are significantly different at odds 

 of 19 to 1. 



Yields v;ere higher in 1978 on the less - severely pruned slender 

 spindle trees and regular pruned trees than on the USDA and tier trees 

 In 1979, yields were higher on the slender spindle, regular and tier 

 trees than on the USDA trees. 



The heading cuts on 1-year-old shoots of the USDA trees removed 

 growth on which fruit spurs would have developed. Furthermore, 

 measurements in 1979 indicated that the average distance of the first 

 blossom cluster from the tip of shoots produced in 1977 was 10 cm 

 on headed-wood in comparison to 2 cm on non-headed wood. This in- 

 dicates that the buds directly behind the heading cuts, made in Feb- 

 ruary, 1978 remained vegetative during the growing season of 1978 



