48 BITTER PIT INVESTIGATION. 



This is the third season during which the laterals have been observed in fruit. They were 

 described and photographed in February, 1914 (Report III., Figs. 10-22). The fruit on the laterals in 

 each of the varieties was free from Pit, although in some instances the rest of the tree was badly 

 affected, as in Shockley and Crow's Egg. 



Owing to the failure of the crop in 1915, only one of the laterals bore fruit, and of the two apples 

 one was clean and one pitted. During the past season, as the table shows, the lateral of every variety 

 produced fruit, and out of twelve varieties eight were free from Pit and four affected. In some 

 instances, as in Crow's Egg, the tree was badly affected, while the fruit on the lateral was clean, and 

 in other cases the fruit on the lateral, as well as on the rest of the tree, was pitted. 



Shockley is a variety very subject to Pit, and the fruit on the tree was carefully picked on 9th 

 March in order to compare with that on the lateral. 



No. of Fruits. Clean. Pitted. Per cent. Pitted. 



Lateral 7 .. 5 .. 2 .. 28 



Rest of Tree .... 732 . . 442 . . 290 . . 40 



Of course, even on a lateral when the yield is very light Pit may develop, and the varying results 

 obtained in the three seasons during which the experiment was conducted show, that a longer period of 

 time is necessary to arrive at final conclusions. 



C. EXPERIMENTS WITH STOCKS. 



Just as the soil has an influence upon the plant which is dependent upon it for supplies, so the 

 stock may be supposed to influence the scion growing upon it. But just what that influence consists 

 in and how it manifests itself has not been accurately determined. We know that the Paradise stock 

 produces a dwarfing effect on the graft, because the stock itself is naturally of small stature, and that 

 Wild Crab apple and pear stocks favour the formation of strong woody shoots. Generally, however, 

 there is some subtle influence exerted, but in what direction it is not always easy to trace, and a number 

 of experiments have been initiated in the definite direction of testing, if the stock influences the develop- 

 ment of Bitter Pit in any given variety. 



It would be both misleading and premature to draw any conclusions as to whether the disease is 

 likely to be influenced by the stock, from the limited time during which the experiments have been 

 carried on. Simultaneous experiments on similar lines in each of the States would require to be 

 continued for a number of years in order to supply reliable data. 



While the main point to be determined is the influence of the stock upon the development of 

 Bitter Pit, attention will be given at the same time to the relative 3'ield of fruit and the relative size 

 of the trees. The influence of the stock upon the growth of the tree, the yield of fruit, and the amount 

 of Pit will thus be shown relatively to each other. 



11. AT BURNLEY HORTICULTURAL GARDENS, VICTORIA. 



(1) BARK-GRAFTING OF LIABLE VARIETIES ON BLIGHT-PROOF STOCKS. Originally six stocks 

 were selected in 1911, but only three have survived (the other three dying from an attack of Root 

 Rot), and the results of grafting on these is shown in the following table : 



TABLE XXVII. 

 BLIGHT-PROOF STOCKS WITH GRAFTS LIABLE TO BITTER PIT. 



Fruits. Per cent. 



Stocks. Grafts. . No. Clean. Pitted. Pitted. Remarks. 

 Coral Crab 



Cleopatra . . 2 grafts; growth very poor 



Annie Elizabeth . . Dead 



Cox's Orange Pippin Dead 



Bismarck . . . . Dead 



