BITTER PIT AND ITS CONTRIBUTING FACTORS. 



77 



and that the cultural methods adopted to produce a large-fleshed juicy apple have had an injurious 

 influence on the constitutional vigour of the tree. The study of fruit trees in all their hearings 

 is just as necessary and just as important, from the point of view of the producer, as that of the 

 wheat-plant or other cereals. 



The principal factors which contribute to the development of Bitter Pit appear to be — (1) 

 intermittent weather conditions when the fruit is at a critical period of growth; (2) amount and 

 rapidity of transpiration ; (.'5) excessive transpiration during the day followed by its sudden checking 

 at night, when the roots are still active, owing to the heat of the soil ; (4) failure of supplies at the 

 periphery of the fruit, followed by spasmodic and irregular recovery ; (5) inequality of growth, so 

 that the vascular network controlling the distribution of nutritive material is not regularly formed ; 

 (6) fluctuations of temperature when fruit is in store ; and (7) nature of the variety. 



How far the result is affected by such factors as cultivation and drainage, manuring and pruning, 

 stocks and irrigation, has yet to be determined by means of observation and experimental tests. 

 The transpiration of a tree is known to be influenced by the heat of the soil in which its roots are 

 embedded, increasing as the soil is heated, and diminishing as it becomes cooler. AM those agencies, 

 therefore, which influence the temperature of the soil in any way will be worthy of consideration. 

 It is well known that a closely-packed moist soil is a much better conductor of heat than a loose dry 

 soil. Hence frequent cultivation, in which the surface soil is kept dry and loose down to the depth 

 in which the feeding roots are situated, would lower the temperature during the day in comparison 

 with that of the same soil left uncultivated. 



Whatever explanation be accepted as to the cause of Bitter Pit, there are always some 

 varieties, such as Yates, to be accounted for, which are not subject to the disease under conditions 

 most favorable to it, and are practically immune. 



It is invariably puzzling to the orchardist, why one variety should escape the pit, and another 

 tree growing alongside should be badly affected ; why some apples in. a cluster should be free, and 

 the rest badly pitted ; why, in short, one should be taken, and the other left. 



Well, although it does not explain, yet it renders the phenomenon less obscure when we 

 consider that no two objects are alike in living nature. No two beings are exactly alike, even in the 

 case of twins ; no two leaves of the same tree resemble each other exactly ; no two seeds of the 

 same plant are ever identical ; and the seeds of the same plant from the same fruit never reproduce 

 exactly the parent plant. It will be understood, therefore, that no two trees, even of the same 

 variety, are identical, and may vary considerably in their root-system, their leaf surface, and their 

 general constitutional vigour. It will be instructive to compare two varieties, such as Cleopatra 

 and Yates — the one exceedingly liable to the disease and the other immune or practically so — in 

 order to discover if there are any peculiarities in their structure to account for the difference, and 

 this will be done during the coming season. When one considers the delicate adjustments necessary 

 between the constantly enlarging network of vessels on the one hand, and the growth of the pulp- 

 cells on the other, it is rather surprising than otherwise, that the fruit is so generally well-formed 

 and shapely. The Yates is a slowly maturing apple, and one of the last to ripen, so that the growth 

 at the periphery goes on in a regular and orderly manner. 



PRACTICAL APPLICATIONS. 



It is easy to show how the above explanation accounts for a number of the observed facta 

 coming within the experience of the orchardist. When a tree is young and vigorous and making 

 rapid growth, it is generally agreed that, at that stage, it is very subject to pitting, and the first crop 

 is often very bad. The conditions are such as to favour rapid transpiration, and the excessive 

 growth will tend to interfere with the regular development of the vascular network equally at 

 every portion of the circumference. It has also been observed that, generally, there is more pit in 

 a light crop than in a heavy one, especially when the fruit produced is somewhat abnormal in size. 



