DISEASES OP THE APPLE. 241 



Treatment: A good preventive is to remove all mummy 

 apples. The only remedy suggested is to spray with Bordeaux 

 mixture late in June or early in July. 



CANKER. 



This is a general term applied to diseased areas vs^here there 

 is a deep seated killing of the tissues. It may take the form 

 of a swelling, a scale, or a crack. 



Cause: The cause of the apple tree canker is a fungus known 

 as Spha£ropsi8 malorum. The Bitter Rot Canker, which occurs 

 on twigs or small branches, is caused by the Bitter Rot fungua 

 entering some wound. 



Description: The apple tree canker is likely to occur on any 

 part of the tree, and on trees of any age, but is more likely to 

 occur on the little trees. The bark becomes rough and cracks 

 open. 



Treatment: Spraying with Bordeaux mixture has been used 

 with good results. The young trees aifected should be de- 

 stroyed, as should all diseased branches and twigs. 



CROWN GALL. 



Cause: It is not known what causes this disease. Mr. Miles, 

 in a paper read before this society in 1903 says: 



"Some crown galls are caused by nematodes or eel-worms. "^ 



Prof. J. W. Toumey, Arizona Experiment Station, says that in 



his opinion the cause may be refered to either one or two closely 



related species of slime-moulds. This seems to be the popular 



opinion at present. 



Description: The crown gall is an irregular enlargement of 

 the tissue of the apple tree, just below the surface of the ground 

 around the crown of the tree. The galls become quite large 

 and undoubtedly interfere with the process of nutrition. The 

 trouble is not easily noticed, being under ground, but if the 

 leaves appear pale and the tree has a general sickly appearance, 

 it is best to examine carefully for this trouble. An examination 

 will probably show an unusual amount of fibrous roots at and 

 below the crown. The disease is commonly a disease of the 



