EXPERIMENTS CONDUCTED WITH A VIEW TO CONTROLLING DISEASE. 29 



one plot, and the lowest yield and the greatest percentage of Pit in another. This relation held even 

 in individual trees, and it will be observed that in those plots where the percentage of Pit was high, 

 it was usually mainly owing to individual trees with light crops. Thus in plot 1 a tree with the lowest 

 yield of 42 Ibs. of fruit had 50 per cent, of Pit, and in plot 2 a tree with 74 Ibs. of fruit had 27 per 

 cent, of Pit. 



In the unmanured plots the average yield per tree was 136 Ibs., while in the manured plots it 

 was 147 Ibs. 



On the whole, the past season was not a bad one for Pit, but to show how variable it is in its 

 occurrence, plot 5, with the least percentage of Pit in 1916, had the greatest percentage in 1915. 



EFFECT OF SULPHATE OF IRON ON PIT. 



A solitary Cleopatra tree which had been consistently badly pitted year after year was selected 

 for testing the effect of sulphate of iron. It was lightly pruned throughout the five years of the 

 experiment, and gave the following results : 



TABLE XI. 

 EFFECT OF SULPHATE OF IRON ON PIT. 



Total Sound Pitted Percent. 



Season. Manure. Yield. Fruit. Fruit. Pitted. 



Ibs. Ibs. Ibs. 



1911-12 No manure 169 139 30 17'75 



1912-13 Sulphate of iron 2 Ibs. 2911 287 4| 1-54 



1913-14 ., 229" 215 14 6-11 



1914-15 lib. 424 404 20 4-71 



1915-16 No manure 37 24 13J 36 



It will be seen from the above that whenever sulphate of iron was applied the yield was increased 

 and the amount of Pit considerably reduced. 



If a comparison is made with individual trees in the manurial plots, the application of sulphate 

 of iron gave the highest yield in every instance, and in season 1914-15, when the yield was 424 Ibs., 

 the highest yield approaching it was 254 Ibs. Sulphate of iron, when applied in proper quantities, 

 seems to have a decided effect in reducing Bitter Pit, and it is worthy of being tried oil a large scale 

 and for a sufficient number of seasons. 



3. AT MR. ROESSLER'S ORCHARD, STANTHORPE, QUEENSLAND. 



There is, unfortunately, no report for these manurial experiments, since the very severe drought 

 experienced, together with the ravages of the parrots by day and the flying foxes by night, has left 

 very few apples on the trees. 



The Orchard Inspector, Mr. J. Henderson, informed me that the cultivation and spraying had been 

 attended to, but the trees had made practically no growth, owing to the drought. As regards Pit, 

 he remarked : "The fruit showed very little Pit on any of the plots ; in fact, so far as Pit was concerned, 

 there appeared to be no difference between the manured trees and the 'buffer' trees." 



4. AT GOVERNMENT EXPERIMENT ORCHARD, BLACKWOOD, SOUTH AUSTRALIA. 



The trees used for these manurial experiments were planted out in August, 1908, when one year 

 old, so that they are now eight years of age from date of planting. The manure has been applied 

 for seven years in succession, and since this is the first year in which the yield was sufficiently large to 

 be reckoned by weight instead of by number of fruits, the results may be taken as affording some 

 indication of the effect of manure and yield on the development of Pit. 



