EXPERIMENTS CONDUCTED WITH A VIEW TO CONTROLLING DISEASE. 35 



manured plots is 27 Ibs., as compared with 106 Ibs. in the previous season, and in the check plots 12 Ibs., 

 as compared with 50 Ibs. 



The highest yield was in plot 6, with superphosphate and sulphate of potash combined with green 

 manuring, while in the previous season it was in plot 9, with superphosphate and sulphate of ammonia. 



The lowest yield was in plot 13, with ground limestone and green manuring, and in the previous 

 season it was in plot 7, with ground limestone alone. Accompanying the small yield there is a 

 considerable increase in the amount of Pit. In the manured plots there is 73 per cent., as compared 

 with 40 per cent, the preceding year, and in the unmanured plots there is 58 per cent., as compared 

 with 20 per cent. 



As before, the Pit is least in the unmanured plots, as might be expected from the relatively light 

 crop and the small size of the fruit. 



The least amount of Pit occurred in plot 11, where sulphate of iron was used alone, and the highest 

 amount in plot 6, with superphosphate and sulphate of potash combined with green manuring. The 

 heaviest yield was associated with the greatest amount of Pit. In the previous season green manuring 

 alone gave the lowest amount of Pit, being practically equal to that of no manure, and sulphate of 

 iron came next. The highest amount occurred in the same plot as the present year, although not 

 associated with the highest yield. 



In the general table (page 36), showing the relation of Pit to the yield obtained and the manures 

 used in the various States, there is a wide variation in respect of yield and Pit. 



The yield ranges from an average of 200 Ibs. per tree to 29 Ibs., and from 86 per cent, of Pit to 

 | per cent. 



Although quite a number of different manures have been tried, only three have been tested in all 

 the experimental plots, viz., a complete manure (superphosphate, sulphate of potash, and sulphate of 

 ammonia), the same without potash, and a third without nitrogen. Taking the most general view of 

 the results obtained from these manures, irrespective of soil or climate, it was found that a complete 

 manure gave the highest yield, without potash the least, and without nitrogen intermediate. 



Comparing these results with those obtained from no manure, both the complete manure and the 

 same without nitrogen gave a superior yield to the unmanured plots, while a complete manure without 

 potash yielded considerably less than the unmanured plots. 



If a similar test is applied to the effect of these manures on Pit, there is no very marked difference 

 between the three manures, but the unmanured plots have decidedly less Pit. This is probably owing 

 to the smaller size of the fruit and the absence of any stimulating effect from the action of fertilizers. 



B. PRUNING EXPERIMENTS. 



These experiments have now been conducted for five years in succession, and the mode of pruning 

 has had sufficient time to produce its effect upon the tree and its fruit. The results are very striking 

 as to the influence of the mode of pruning upon the development of Bitter Pit, and they have induced 

 me to give prominence to such subjects as fruit-buds in relation to pruning and the pruning of apple 

 trees grown in pots. 



In the Fifth Report of the Woburn (England) Experimental Fruit Farm (1905) the introductory 

 paragraph under the heading of ''Experiments on Pruning" is so appropriate to our own that I 

 make no apology for quoting it : 



"Experiments on pruning must always be somewhat uncertain in character, for pruning 

 is an art and depends greatly on the skill and judgment of the pruner. The work must of 

 necessity be left in the hands of the ground-manager, and, as is well known, even the most 

 highly skilled horticulturists differ amongst themselves in the application of their art. 

 There is always a possibility, therefore, that under different management the results might 

 have been somewhat different. According to our own personal opinion, which seems to be 

 borne out by some of the experiments themselves, the pruning in the past years has erred on ' 

 the side of being too severe, and especially in removing too many laterals, or cutting them 

 back too close to the branches. A less severe treatment will be adopted in future, and as 

 regards the standard trees the pruning will be confined to the removal of superfluous 

 branches." 



