6 BITTER PIT INVESTIGATION. 



It is mainly owing to this controlling influence which the orchardist can exercise over his 

 individual trees, that the success of measures for the prevention or mitigation of Bitter Pit is rendered 



possible. 



Finally, the possibility of placing the apple, after removal from the tree, in cold storage, where 

 the development of Bitter Pit is retarded, and the ripening process arrested, is a factor of prime 

 importance. The fluctuating conditions of temperature and humidity can be regulated, so that the 

 apples practically remain, and can be taken out, in the same healthy condition as when put in. The 

 early losses which attended the over-sea shipment of fruit can now be prevented, and there is no 

 longer any excuse for fruit arriving at its destination in an over-ripe or pitted condition. 



It will thus be evident that our means of controlling Bitter Pit have been largely increased 

 owing to a knowledge of the contributing factors. These factors include every phase in the life of the 

 tree, from the nursery where it is reared to the orchard where it is planted, so that the general bearing 

 of this investigation must be kept in view as well as the particular issue to which it is finally directed. 



The experimental results will now be considered, in so far as they affect the practical measures 

 to be adopted for preventing or lessening the disease. And since it was laid down in my first report 

 " that the final test of the results obtained must be their actual value to the practical man," the 

 investigation will appropriately be brought to a conclusion by showing some of its practical applica- 

 tions. 



I. DEVELOPMENT OF BITTER PIT AFTER APPLES ARE 

 GATHERED X-RAY TREATMENT. 



It will be remembered that in explaining the cause of Bitter Pit in Report II., a distinction was 

 drawn between the disease developing while the apples were still growing on the tree, and its develop- 

 ment in fruit which showed no signs of it on the tree, but afterwards appeared on keeping. The 

 importance of this distinction lay in the fact that if the disease originated anew in store, then some 

 further explanation was required to account for it. 



There is a general impression that it may exist in an incipient stage, although not discernible 

 on the exterior, and this view was supported by the well-known fact that sometimes apples were 

 found to be pitted although there was no external sign of it. In order to settle the matter on a scientific 

 basis, X-ray treatment was adopted, but hitherto no definite result was obtained, because the par- 

 ticular apples experimented on showed no sign of Pit under the X-rays, and no Bitter Pit afterwards 

 developed. This was only negative evidence, but now positive evidence has been obtained that those 

 apples which show some flaw in the flesh afterwards develop the Pit on keeping. 



For the purpose of this experiment I picked on 18th January, 12 Cleopatra apples from a tree 

 which had already borne pitted fruit, when they were rather more than half -grown. They were all 

 carefully scrutinized, and found to be perfectly sound, as far as naked-eye appearances went. Six of 

 them were submitted to the X-rays by Dr. Ferguson Lemon, of Melbourne, on 20th January, each 

 with their respective number, and the remaining six were retained as a check. Only one of the six 

 that were submitted to the X-rays showed a flaw in the flesh. This flaw was immediately beneath 

 the skin, as shown in Fig. 1. All were kept under the same conditions in my laboratory. 



Early in April they were finally examined, and No. 3 was the only one showing signs of Bitter 

 Pit. Both X-ray photographs and ordinary photographs were taken of this particular specimen, 

 and the original flaw beneath the skin can still be seen, with the addition of the development of a 

 number of brown flecks throughout the tissue. (Fig. 2.) 



It would appear that the X-rays can discriminate between the honeycombed tissue 

 characteristic of Bitter Pit and the solid flesh of the healthy apple. The check also showed one 

 apple pitted when examined at the same time. Although only a limited number of specimens were 



