8 BITTER PIT INVESTIGATION. 



In all some 600 apples were kept under observation under various conditions, often more than 

 a month, in the hopes that some suggestion might be obtained of the conditions influencing the sub- 

 sequent appearance, or non-appearance of Pit. It is very strongly felt, that if the conditions respons- 

 ible for the appearance of Pit are in action, subsequently to the gathering of the apple, the different 

 laboratory histories of the many apples received, and kept under controlled conditions, should show 

 some variety of influence upon the incidence of Pit. Clean apples, all from the same tree, were kept 

 in separate groups under such varying conditions as : 



(a) Laboratory room fluctuations. 

 (6) Saturated moist air at 27 C. 



(c) Dry air at 30 C. 



(d) An atmosphere of carbon dioxide. 



It is necessary, however, to point out, that in spite of the almost untiring assistance given by 

 Mr. Me Alpine in procuring material, it seemed almost impossible to hit upon just that class of material 

 really desired the apparently clean apple, which was to Pit on being kept. 



The plan mapped out for the various investigations was to procure some five dozen apples all 

 from the same tree. 



The tree was to have a bad reputation as regards Pit, and might even have pitted apples upon 

 it. The five dozen selected apples were, however, to be clean. 



They were then divided into three or four batches (usually 20 apples in each batch, if possible), 

 and each batch was then placed under the different conditions previously referred to. Frequent 

 examinations were made for the appearance of Bitter Pit, and any pitting was carefully noted. Often 

 too, the presence or absence of starch in the apples was determined in the hopes that material might 

 be found, showing definite survival of starch patches, sufficient to indicate the probability of an early 

 Pit area not yet dead and browned. This point will, however, be treated under a separate paragraph. 



To return, however, to the experiments under the above conditions, it may be said, that 

 though the varieties of apples employed were selected for their susceptibility to Pit, and though they 

 had been gathered in nearly all cases from trees actually having many pitted apples this particular 

 season (1915), yet they remained particularly clean, only one or two apples developing a single or 

 sometimes two Pits out of a batch of 20 under experiment. Such a low and insignificant disease 

 incidence prevents any dogmatic statistical comparison as to the respective merits, or disadvantages 

 of the laboratory treatment, but indicates that the apples were inherently clean, and not to be en- 

 couraged to Pit even by such unorthodox methods of keeping as water saturated air at 27 C., for a 

 month or more at a time. 



In the only definite experiment which showed any distinction between groups of apples held 

 under different conditions, the results were as follows : 



ANNIE ELIZABETH APPLES DIAMOND CREEK. 



APPLES FROM ONE TREE. 

 Group I. 16 Apples. Group II. 20 Apples. Group III. 24 Apples. 



On laboratory table. Dry air at 26-30 C. Moist air (saturated). 



Day temp, fluctuated 64-88 F. Equals 79-87 F. 26-28 C equals 79-83F. 



Jan. 7th Commenced experiment. 

 12th 3 well pitted, 1 with 3 Pits, 1 All clean. 1 Pit, 1 markedly pitted. 



with 1 Pit. 



27th 6 well pitted, 5 slightly. 1 with Pit-like groove. 2 with 1 Pit, and 1 marked. 



Feb. 5th No further change. Ditto. Ditto. 



NOTE. The night minima ranged from 50-60 F. Argus. 



The experiment indicates that the steady high temperatures led to a less percentage of pitting 

 (5 per cent, for dry oven, 12 per cent, for moist oven, as against 69 per cent, for room with its fluctuating 

 temperature). 



