DEGENERATION OF APPLE TREE VARIETIES. 



67 



natural limits are set upon the duration of a variety. He admits that varieties are constantly liable 

 to decay or become worthless, but he attributes it to — ■ 



1st. Grafting upon unhealthy stocks ; 



2nd. Carelessness in selecting scions for grafting ; 



3rd. Unfavorable soil and climate, deterioration arising from a want of constitutional 

 fitness for a climate different from its natural one. 



As an example of a long-lived sort the Winter Pearmain may be mentioned, which is one of 

 the oldest apples on record, and, as shown by Hogg, is referred to as early as the year 1200. 



The view of the continuity of the individual through all its various detached portions of buds 

 and grafts is based on the assumption that they all retain the original characteristics unaltered, but 

 there is a modifying influence introduced in the mutual action of stock and scion, and even the soil 

 and climate may alter the fruit as regards size, colour, and taste. 



After long continued cultivation there may be a failure or decline of varieties, not necessarily 

 due to old age, but to a change in the environment, such as mode of cultivation and weather, and 

 to a change in the character of the variety. 



Conclusions drawn from annuals, such as wheat, do not necessarily apply to perennials such 

 as apple trees and vines, so that the opinions quoted here will only apply to perennials. The 

 Government Viticulturist for Victoria, F. de Castella, with both Continental and Australian 



experience, does not believe in " variety degeneration " with regard to the vine, for he writes : 



" 1 cannot say that I know of any vine varieties which have degenerated from old age, although you 

 have, no doubt, heard of the stupid theory which prevailed at one time in France that phylloxera 

 was due to degeneration resulting from long continued propagation by cuttings. Some of the vines 

 now cultivated in France are considered to be of great antiquity, and yet they are quite as strong 

 as recently raised seedlings." 



Mr. G. H. Johnston, of the Experiment Farm, Bathurst, New South Wales, has submitted 

 the theory of " varietal degeneration " to account for Bitter Pit. He starts from the well-established 

 fact that some varieties are more liable than others, and instances as worst affected Cleopatra 

 and Annie Elizabeth. " These are only selected as types, but will be found to be varieties which 

 have long been grown." Now Annie Elizabeth is a seedling raised by Messrs, Harrison and Son, 

 of Leicester, and received a first-class certificate from the Koyal Horticultural Society in 1866, so 

 that the statement — " the wood now used for grafts may, I think, be considered as being of a great 

 age " — does not apply. Various other seedlings might be mentioned as being very susceptible, and 

 which are not of a great age, such as Lord Wolseley, originated in New Zealand, and Prince Bismarck, 

 in Victoria. 



Therefore the explanation offered — " that the trees, owing to their age and consequent 

 weakening, become more liable to this breakdown of cells than others " — falls to the ground. But 

 the propounder of the theory recognises that " senile decay " is not always at work, for young and 

 lately constituted varieties produced from seed may be sometimes pit-liable and sometimes resistant. 

 So that, finally, he comes to the conclusion that the degeneration of varieties through continuous 

 propagation by cuttings without the intervention of a sexual generation is the cause of Bitter Pit. 



While we have not sufficient knowledge of the life of perennial plants, such as the apple tree, 

 to say definitely whether it is capable of unlimited vegetative growth, nor sufficient evidence to 

 conclude that the constant repetition of the parent form by budding and grafting has a tendency 

 to weaken the constitution of the tree, there is no evidence brought forward to show that the 

 presumed weakening effect is responsible for the occurrence of Bitter Pit. We must distinguish 

 between the life of the individual tree and the life or continuance of the variety — between old and 

 young trees and old and young varieties. An apple tree, when grown under suitable conditions, 

 may reach a good old age. In Bunyard's (103) "Apples and Pears," reference is made to very old 



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