GEOGRAPHICAL DISTRIBUTION OF DISEASE. 



69 



Mr. Johnston has not proved the connexion between degeneration and Bitter Pit I heartilv indorse 

 his concluding recommendation—" Nurseries should be established,, where definite crossing would 

 be carried on, and the seedlings tested by fruiting under conditions which would make for the 

 development of the disease." 



XX.— GEOGRAPHICAL DISTRIBUTION OF DISEASE. 



In the historical account of the disease already given, it has been shown that it occurs in 

 Europe and Africa.. Canada and the United States, and in Australasia. It has not been discovered 

 in Asia, although it probably exists there. 



In the United States this disease is very prevalent, and Dr. Galloway, Chief of Bureau of 

 Plant Industry, writes as follows, under date 24th November, 1911 :— "Bitter Pit in apples and 

 pears is quite common in the United States, especially in the western irrigated orchards, where 

 conditions are probably more like those in South Africa and Australia than the conditions in the 

 older orchard districts of this country, which are in humid climates. In the Western States Bitter 

 Pit occurs, but in the humid moister part of the country certain fruit-spot fungi, especially the 

 Cylindrosporium discovered by Brooks, are usually more prevalent than the true Bitter Pit." 



In a recent investigation by Brooks (101), he has found the "fruit spot" not only on the 

 apple, but also on the quince. A Phoma stage has been discovered for the fungus causing it. so 

 that the name is now changed from Cylindrosporium pomi Brooks to Phoma pomi Passer. This 

 disease has not yet been met with in Australia, but it is readily controlled by spraying, and there 

 is thus a clear distinction between the "fruit spot" and the "fruit pit" of the apple. 



H. T. Giissow, Dominion Botanist for Canada, writes, under date 25th January, 1912 — 

 " Bitter Pit in Canada is one of the most troublesome injuries known to fruit-growers. It is present in 

 practically all localities. My acquaintance with this disease is not only confined to its presence in 

 Canada, but I also know that it is widely distributed in Great Britain and other European 

 countries." 



Even in England the disease has been extremely prevalent during 1911, and it is worthy of 

 note that the summer was exceedingly hot and dry. 



XXI— BITTER PIT AND ITS CONTRIBUTING FACTORS. 



It is a recognised principle of pathology that the normal structure and function of the part 

 or organ concerned should be first studied and understood as far as possible, and then the abnormal 

 condition of the same may be satisfactorily dealt with. So the structure and functions of the 

 apple and pear were carefully investigated, with the result that not only was there found a perfect 

 system of vessels supplying the " core " and ramifying among the cells of the flesh, but also 

 immediately beneath the skin a beautiful network of vascular bundles to regulate and equalize the 

 distribution of nutritive material in the area where the most rapid and greatest amount of growth 

 was normally taking place. This network will be found to play an important part in connexion with 

 Bitter Pit. I have now described the characteristic features of the disease as exhibited not onlv 

 in Australia, but in other parts of the world, and have reviewed the various agencies which were 

 supposed to account for it, and it has been shown that neither insects nor fungi, bacteria nor 

 external agencies, are concerned in it. Clear proof has been given that Bitter Pit is an internal 

 disease due to internal causes. 



