80 SITTER PIT INVESTIGATION. 



with each experiment station the nature of the soil as determined by chemical and mechanical 

 analysis, the rainfall and the drainage, the mode of cultivation, and the system of pruning adopted,, 

 age of trees, together with the altitude and such other details as will enable any orchardist to form 

 a clear conception of the accompanying conditions in each case. 



Now that an insight has been gained into the factors which contribute to the development 

 of this disease, efforts can be directed towards the discovery of preventive or remedial measures, 

 which will not only enable the fruit to be gathered from the tree without the unsightly " pit," but 

 also to insure that when the fruit is packed clean it can be exported without any development of 

 the disease on the voyage. 



We cannot control the weather, so we must turn our attention to the soil and the tree itself, 

 which are capable of being controlled to a large extent. As regards the soil, there are three 

 principal methods employed. By means of tillage or cultivation, the soil can be pulverized and 

 rendered more suitable for plant-growth, weeds can be kept down, and a mulch formed to decrease 

 the loss of water by evaporation. The heat of the soil may also be regulated to a certain extent. 

 Rotation of crops is another means employed, but with fruit trees green manuring takes its place, 

 by adding humus to the soil and thereby rendering it more retentive of moisture and more 

 absorbent. 



The application of fertilizers is also a well-known method of improving the soil physically, 

 chemically, and biologically. Lime, for instance, improves the physical texture of the soil, acts 

 chemically by liberating potash and neutralizing acidity, and it has a biological effect by encouraging 

 certain classes of bacteria. 



Irrigation may also be added as a means of control over the supply of moisture in the soil. 



All these agencies are employed in the experimental tests now being conducted in connexion 

 with Bitter Pit. 



In the case of the tree, control may be exercised by selecting the varieties to be planted, by 

 using the stocks best suited to the variety, and by the adoption of suitable methods of pruning. 

 Cold storage has an undoubted influence on the keeping quality of the fruit, and all these measures 

 must be tested in an experimental way. 



A. — MANUKIAL EXPERIMENTS. 



For manurial experiments in connexion with Bitter Pit, it is necessary to have a sufficient 

 number of trees of a liable variety, similar in age and size and all in bearing, planted in soil fairly 

 equal throughout. It is not always easy to secure such conditions in an ordinary commercial 

 orchard, but they must approximate to this standard in order that the results may be comparable. 



It is desirable to have at least eight or ten trees in each plot, and there must be a barrier 

 or guard plot on each side to prevent the intermixing of the manures from the spreading of the 

 roots. 



Since the fruit is mainly nourished from the food supply already stored up in the fruit-buds 

 and other portions of the tree, it is evidently misleading to draw conclusions from the effects 

 produced on the fruit by one season's application of manures. Only in the case of quick-acting 

 manures, such as nitrate of soda, is any effect produced in the season during which it is 

 applied. 



The effect of sulphate of iron has been tried on Cleopatra apples in a Goulburn Valley 

 orchard. It was' used at the rate of 3 lbs. per tree, but, although it gave a deep-green healthy 

 colour to the leaves, with an extra good yield, there were pitted apples on all the trees, and the 

 disease developed further in store. Mr. W. L. Summers informs me that the Director of 

 the Botanic Gardens, Adelaide, found much less pit after applying 2 to 3 lbs. of sulphate of 

 iron per tree. This salt is being used by itself and in combination in the different manurial 

 experiments. 



