PRUNING EXPERIMENTS WITH APPLE TREES GROWN IN POTS. 19 



V. PRUNING EXPERIMENTS WITH JONATHAN, LONDON PIPPIN, 

 AND KING DAVID APPLE TREES GROWN IN POTS. 



When apple trees are grown in pots, it is possible to follow in detail the effects of removing certain 

 portions of the tree in pruning, a method which would hardly be practicable with large trees grown in 

 the orchard. On this account such an experiment enables us to confine our attention to a limited area 

 and determine exactly how the tree itself is affected as regards growth and how the yield is controlled 

 by the treatment given to each individual branch. 



Although the conditions of a pot experiment are necessarily different from those found in the 

 orchard, yet the results obtained indicate the effect of certain measures under such conditions. When 

 these results are compared with others obtained under natural orchard conditions, they will be found 

 to supplement each other and suggest fresh lines of research. 



For the purposes of this experiment I have selected three varieties in their third year, grown in 

 12-inch pots at Burnley Horticultural Gardens. Two of them are extensively grown in Victoria, 

 viz., Jonathan and London Pippin or Five Crown. As usually treated these two varieties represent 

 two different types of pruning which are in vogue. In the case of Jonathan the growth of laterals is 

 encouraged, because it is on these that the crop is chiefly borne, more so than on the main limbs. 

 Whereas on the London Pippin the laterals are almost entirely suppressed, because the bulk of the 

 fruit is said to be produced along the main limbs. 



Such is the traditional view of the proper mode of pruning these two typical varieties. But when 

 pruning experiments with London Pippin were continued over a period of five years in succession it 

 was found that the lightly pruned trees in which the laterals were allowed to grow freely produced 

 slightly larger crops than the trees in which the laterals were severely pruned, and the amount of Bitter 

 Pit was a negligible quantity. 



The following descriptions and tabulated details refer to the trees after pruning : 



JONATHAN. 



This tree, budded on the Northern Spy, is three years old. It was cut back hard last year, and 

 was severely pruned this year on 12th July. Its height is 4 feet 4 inches, its spread of branches 3 feet 

 1 inch, and its girth round the stem immediately above the union is 2|- inches. 



It consists of a main stem with five leaders or primary branches. The main stem reaches a height 

 of 19 inches from the ground, and the five leaders are described in order from below upwards. Each 

 individual leader is minutely described, and the one-, two-, and three-year-old wood is distinguished 

 with their respective growths and the various laterals, spurs, buds, flowers, and fruits arising from 

 each. 



In pruning, the same weight of wood was practically removed from each leader, with the 

 exception of the topmost one, where the prunings weighed one ounce instead of one-eighth of an ounce 

 as in the others. 



Last season (1915-16) the tree bore 23 apples, all of which were free from Pit (Figs. 35, 38). 



LONDON PIPPIN OR FIVE CROWN. 



This tree is also three years old, and budded on the Northern Spy. It was severely pruned on 

 the same date as Jonathan. It has a height of 4J feet, a spread of branches of 5 feet 1 inch, and the 

 girth of stem above the union is 2J inches. 



It consists of a main stem with five leaders, as in Jonathan, and the details are given in the table. 



The tree bore 22 apples last season. Of the 20 apples on the tree only one was pitted, and this 

 pitting (not crinkling) is distinctly seen in the topmost apple. There were two windfalls, one of which 

 was pitted, so that the amount of Pit was 9 per cent. (Figs. 36, 37). 



