Bitter Pit in Ajyple^. 3 



of these fruits were obtained from three trees at Burnley at 

 fortnio-htly intervals. The trees, which are grafted on to Nor- 

 thern Spy stocks, are about 9 years old, and blossomed in 1910 

 between October 13th and 20th. 



On December 12th, though there was no external evidence of 

 bitter pit, in one apple I found just under the surface a few 

 groups of cells which were emptier and very slightly larger 

 than the surrounding cells (see Fig. 1). These were figured and 

 labelled as possibly having some connection with bitter pit. 

 The fruits examined during the next month were quite healthy, 

 but specimens gathered at Burnley on January 9th, 1911, and 

 forwarded to me in Sydney, were found to be badly pitted. 



Previous Theories. 



The many theories as to the cause of this complaint which 

 have been put forward by various workers are tabulated in a 

 paper written by Mr. Pole Evans,i who also enumerates reasons 

 for their rejection. Mr. Evans himself, speaking of South 

 African apples, says he believes the disease is caused by the 

 bursting and consequent breaking down of certain cells of the 

 flesh due to too great internal pressure. 



In order to test this theory Prof. Ew^art punctured very young 

 apples with the finest sterilised steel needles. When the fruits 

 ripened it was found that in most cases the wound had com- 

 pletely healed, or, as happened in a few instances, there w^as a 

 surface scar produced which was totally unlike bitter pit. This 

 shows that bursting of the cell w^all does not produce this con- 

 dition. (See Fig. 2.) 



History of the trouble. 



I cannot find the exact date at which bitter pit was first 

 observed, but it seems to be a comparatively new disease which, 

 in Australia at least, appeared somewhat suddenly about the 

 late eighties or early nineties of last century. 



Crichton in the Australian Fruit Ctilturist,^ published in Mel- 

 bourne in 1893, but I suppose written some years previously, 



1 Transvaal Department of Agriculture, Technical Bull. No. 1, July, 1909. 



2 The Australian Fruit Culturist, vol. 2. 



2a 



