EXPERIMENTS CONDUCTED WITH A VIEW TO CONTROLLING DISEASE. 39 



fluent" form, as in small-pox, whatever measures are found to alleviate the one may be expected to 

 produce a similar effect on the other. 



The following summary will show how the London Pippin has been affected during the last five 

 seasons, sometimes taking the form of Pit, and only an occasional apple crinkled ; or it may be the 

 reverse, and to the eye of the ordinary orchardist only the crinkled form is apparent. 



SUMMARY OP THE RELATIVE AMOUNTS OF PIT AND "CRINKLE" FOR FIVE CONSECUTIVE YEARS. 



Season. 

 1911-12 



1912-13 



1913-14 

 1914-15 

 1915-16 



No. of Yield. 



Trees. Ibs. Pit and "Crinkle." 



10 1108 Very slight highest 23 apples with 

 leader pruning, and 5 apples with no 

 pruning. 



9 1361 Varying from 15 per cent, with no 

 pruning to 30 per cent, with severe 

 pruning. 



9 956 Amount too small for giving percent- 



age : 6 Ibs. pitted, and 2 Ibs. crink- 

 led. 



9 560 Varying from 5 per cent, with no 



pruning to 50 per cent, with severe 

 pruning. 



9 1891 Varying from '9 per cent, with light 

 pruning to 3J per cent, with leader 

 pruning. 



Prevalence of Pit or "Crinkle." 

 "Crinkle" only an occasional 

 apple pitted. 



Pitting most prominent, and 

 "crinkle" in abeyance ; 231 

 Ibs. pitted, and 63 Ibs. 

 "crinkled." 



Pit three times the amount of 

 "crinkle." 



"Crinkle" most prominent 96 

 Ibs. crinkled, and 12 Ibs. 

 pitted. 



Pit, with only an occasional 

 apple crinkled. 



EFFECT OF ZINC BAND ROUND TRUNK OF TREE. 



There was no evident advantage from the constriction of the stem of the tree by the zinc band, 

 either as regards the yield or the amount of Pit. The trees with the highest and the lowest yield 

 respectively were constricted, and there was no appreciable lessening of the Pit. The finest fruit was 

 produced by tree No. 9, which was constricted, but tree No. 3 was nearly equal, without the zinc band. 



7. AT ALBERT SMITH'S ORCHARD, DEEPDENE, NEAR MELBOURNE. 



This is now the fifth consecutive year in which these Cleopatra apple trees have been variously 

 pruned, commencing in August, 1911. The pruning was done each year by Mr. E. E. Pescott, Principal 

 of the School of Horticulture, Burnley, and thus there was continuity in the methods employed. 

 There are twelve trees in the experimental block, arranged in four rows of three trees each, and each 

 row has been pruned according to a definite system. The leader, light, and severe methods of pruning 

 have been already explained ; one row has been left unpruned as a check (Fig. 41). 



The trees were at a very suitable age to start with, viz., nine years old, and since they are all 

 growing alongside of each other, of the same age, similar in size and vigour, grafted on the same stock 

 (Northern Spy), and treated alike in every respect, with the exception of pruning, I consider that the 

 natural conditions were most favourable for an experimental test of the effect of different methods 

 of pruning on the development of Bitter Pit in a variety very subject to it. 



Besides, it is well known that trees sometimes take a few seasons to respond properly to systems 

 of pruning differing from that to which they have been accustomed, and the five years' continuous 

 pruning on the same system should by this time exhibit its special effect on the fruit of the tree. This 

 effect is very decided, and very instructive as far as Bitter Pit is concerned. 



The nature of the past season forms a striking contrast to that of 1914-15, when, owing to the dry 

 weather and the unusual heat early in October, the Thrip pest was very bad, and this, combined with a 

 severe frost in October, prevented the setting of the apple fruit. That season's enforced rest has 

 evidently reacted favourably on the present one, for the yield is one of the most prolific known. 



