APPLE DISEASES 



493 



whole tree will have leaves streaked with 

 yellow. 



Not pathological. 



Tolntella Rot 



Tolutellose 



A black rot of apples, closely imitating 

 in appearance that caused by Sphaer- 

 opsis, but differing from sphaeropsose in 

 several details, is reported from South 

 Carolina.* 



In general appearance the disease con- 

 sists of a rotten black spot, the spot in- 

 creasing in size until it eventually en- 

 compasses the whole fruit. The central 

 and older portions of the decayed region 

 are of an intense coal black color. The 

 younger region of the spot, its outer 

 border, a zone about five-eighths of an 

 inch wide, is brownish. 



Spray as for scab and black rot. 



THE WATER (ORE OF APPLE 



P. J. O'Gaba 



Water core of apple is a trouble which 

 is not restricted to any one district where 

 apples are grown, but is found to occur 

 more or less generally over the country, 

 particularly in the arid and semi-arid 

 districts. Reports of this trouble have 

 also come from apple-growing districts of 

 Europe, Asia and Africa. Although the 

 trouble has been known for some time, 

 data of very little importance is to be 

 found in American plant pathological and 

 physiological literature. It seems that 

 very little serious work has been done in 

 the matter of determining the true cause 

 of the disease. Some European writers 

 have held that the disease is caused by 

 bacteria, although others have shown that 

 the trouble is not due to any parasitic 

 agency. 



The writer has done considerable work 

 on this disease during the past few years, 

 and in no case has it been possible to 

 identify any organism as the causative 

 agent. All the methods known to modern 

 bacteriology especially those used in the 

 study of ultra-miscroscopic organisms, 

 have failed to show the presence of any 

 organism. Numerous attempts have been 



made to inoculate healthy fruits by in- 

 jecting the juice from water-cored spots 

 of diseased apples, but in no case did the 

 inoculated fruits develop anj' symptoms 

 of water core.(l) The writer has noted 

 the presence of various organisms, espec- 

 ially Alternaria sp., but in no case could 

 it be shown that any organism caused 

 the disease. 



The characteristic appearance of water- 

 cored apples is so well known that a 

 minute description is hardly necessary. 

 The affected apples have hard watery 

 areas extending outward from the outer 

 edges of the seed cavities. In the begin- 

 ning stages, the first appearance of water 

 core is in connection with the vascular 

 system. Each bundle will show a water- 

 soaked area surrounding it, and, as a rule, 

 this area makes its appearance a short 

 distance from the stem. As the vascular 

 system is variously branched upward, 

 water-soaked areas may appear at almost 

 any place in the fruit. In the later stages 

 the seed cavity usually contains liquid, and 

 the hard inner membrane of the carpels 

 is cracked and covered with hair-like 

 growths which finally assume a brownish 

 appearance. The fruit has a somewhat 

 sweetish, fermented flavor, and the watery 

 parts contain more sugar and less acid 

 than the normal or unaffected parts. It 

 is during the later stages of the disease, 

 especially where cracks appear in the ca- 

 lyx or blossom end, that we find fungi and 

 bacteria present. Alternaria sp. is a com- 

 mon intruder, and produces a serious core 

 rot. This latter trouble, namely, Alterna- 

 ria infection, may be prevented by the 

 proper and timely application of Bordeaux 

 mixture. 



It must be understood that no single 

 condition may produce water core; as a 

 rule, it is a combination of perhaps two 

 or more factors. In some cases avoidance 

 of the trouble may be possible; however, 

 for the most part, it is entirely impossible 

 to prevent it because of the fact that cer- 

 tain climatological factors enter into the 

 problem. The most prominent factors in- 

 ducing water core are: 



• North Carolina Experiment Station Bul- 

 letin No. 206. 



(1) O'Gara. P. .T. Water Core of .^pple. 

 Office of the Pathologist and Entomolosist for 

 Rogue River Valley, iledford. Oregon. Bulletin 

 9. October 11. 1912. 



