72 



BITTER PIT INVESTIGATION. 



disease first appeared. In the replies to questions it was generally stated to be when about three- 

 parts to nearly fully grown, and only two orchardists observed it in an early stage of the fruit, one 

 " when about the size of a large walnut," and another, " in bad cases, before Christmas, when the 

 fruit is the size of a walnut." 



The stage at which it appeared in the Gardens was found to be different for different 

 varieties, although it was generally at the period when the fruit was half-grown or approaching 

 maturity, and that is a time of rapid growth. Its earliest appearance was on 7th December, 1911, 

 when it was observed on Garden Royal (almost ripe, but green), Washington (about two-thirds 

 grown), Dartmouth Crab (about three-quarters grown), White Transparent (ripe), Borrowdale 

 (nearly ripe), and Murray's Hawthornden (about half-grown). They are all soft-fleshed apples, 

 with the exception of Dartmouth Crab and Murray's Hawthornden. 



But the earliest of the season was forwarded to me from Orange, New South Wales, by the 

 local inspector, dated 30th November, 1911. These specimens were of special interest, as the same 

 trouble had previously been investigated by Dr. A. N. Cobb (15), and referred to under the heading 

 of " An Obscure Disease of the Apple." They were of the Snowy Apple, or Pomme de Neige 

 variety, a rapidly-growing, quick-maturing, and soft-fleshecl apple. The disease had been present 

 since they were the size of walnuts, and the discoloration of the flesh apparently started at the core. 

 There are two possible ways in which the brown spots may adjoin the core and be scattered through 

 the flesh, as well as appear beneath the skin. If the fruit is affected at an early stage, such as that 

 shown in Fig. 74, when it is practically all core and very little flesh, then the brown tissue would 

 necessarily adjoin the core, and further growth might leave it in that position. Or, if at a later stage 

 it occurred beneath the skin, then the browning might extend inwards along the course of the 

 vessels. 



ITS OCCURRENCE TOWARDS THE - EYE" END. 



In examining a number of pitted apples, one cannot fail to notice that the pits or depressions 

 are not uniformly distributed over the surface, but that they are mostly on the upper half, 

 and usually towards the " eye " end of the apple. This is a very suggestive fact, and when 

 an explanation is attempted, it seems to throw some light upon the origin of Bitter Pit 

 itself. 



In the first place, it is found that the openings in the skin (stomata and lenticels) are much 

 more numerous in the upper than in the under portions of the fruit. A Yates apple was dipped in 

 a solution of caustic potash, which enabled the skin to be easily removed. A square centimeter of 

 the transparent skin from the blossom and stalk end respectively was taken, and on counting the 

 lenticels it was found that there were 81 in the former and 26 in the latter, or a ratio roughly of three 

 to one. 



Professor Brooks (9) also verified this in the Baldwin and Northern Spy apples. "A square 

 centimeter was marked off on the stem half of an apple and another on the blossom half, and the 

 lenticels counted on these areas. By averaging the results secured from ten Baldwins, the ratio 

 of seven to four was obtained as that existing between the number of lenticels on the blossom and 

 stem halves of the apple. On Northern Spies, the ratio was, approximately, five to three." The 

 larger number of openings will necessarily allow more active transpiration to go on at the blossom 

 than at the stalk end. 



In the second place, chemical analysis has shown that there is less water in the flesh there, 

 owing to the extra transpiration. 



For purposes of analysis, apples of the Annie Elizabeth variety, about half-grown, were picked 

 from a tree in the Burnley Gardens on 31st January, 1912. A pitted and a clean apple were chosen 

 of practically the same size from the same tree, and divided lengthwise into three sections, one of 

 which was further divided crosswise into an upper, an under, and a middle portion. After removal 



