Regular type Pruning . This system involved selection o£ branches 

 symmetrically arranged around the vertical axis of the tree and 

 spaced far enough apart to avoid limb crowding when the trees be- 

 came larger. Less temporary branches were left to provide addi- 

 tional leaf surface than on the slender spindle trees. Whorls of 

 branches were eliminated in order to allow only one branch to 

 develop at a given level. The dominance of the central leader was 

 maintained by suppressing or removing competing leaders. 



Results and Discussion 



USDA System. We found 



having 

 summer . 

 trees - 

 Tier tr 

 minutes 

 was not 

 heading 

 by the 

 trees b 



to make heading 



In March, 197 



2.2 5 minutes; 



ees - 0,91 minu 



The time req 



recorded. Mos 



cuts on the US 



regular system. 



ut most time co 



the US 

 cuts a 

 9, prun 

 (b) Reg 

 tes ; an 

 uired t 

 t time 

 DA tree 

 Few c 

 nsuming 



DA system to be time consuming due to 

 nd remove competitor shoots during the 

 ing time per tree was: (a) USDA 

 ular-type trees - 1.66 minutes; (c) 

 d (d) slender spindle trees - 0.66 

 o summer prune the USDA and tier trees 

 consuming during dormant pruning were 

 s and pruning decisions on those pruned 

 uts were made on the slender-spindle 

 was pruning decisions. 



The heading cuts during dormant pruning followed by removal of 

 competitor shoots in late May failed to encourage growth behind the 

 area of removal in 1976 and 1977. However, in 1978 and 1979 lateral 

 shoots behind the heading cuts were longer on the headed than on 

 the non-headed 1-year-old shoots on scaffold branches (Table 1) , 

 but the response was much less than that shown in photographs in 

 USDA Agriculture Handbook No. 458. This can be noted when compar- 

 ing branching on the tree shown in Figure 5 with that shown in Figure 

 6. 



Table 1. Current season lateral shoot growth on headed and non- 

 headed 1-year-old shoots of Spartan apple trees^. 



Type of pruning on 

 1-year-old shoots 

 on scaffold lii±)S 



Mean length of current 

 season lateral shoots on 

 1 -year- old wood (cm) 



Current season lateral 

 shoots longer than 4 cm 

 on 1-year-old wood (%) 



1978 



1979 



1978 



1979 



Heading cuts 



USDA system 



No heading cuts 



Slender- spindle trees 

 Regular-pruned trees 

 Trees with linijs in 

 tiers 



5.4a^ 



3.3b 

 3.7b 



3.3b 



5.3a 



2.3b 

 2.0b 



1.8b 



32a 



lib 

 16b 



14b 



26a 



10b 

 6b 



5b 



Trees planted in 1975. 



Means in columns not having letters in common are significantly at odds of 19 to 1, 



