176 Report of the Botanist of the 



sharply defined and of yarious sizes from one-half inch to three 

 inches or more in diameter and often coalesced to form large 

 areas. 



These areas occurred on all sides of the limbs, and branches 

 were frequently killed outright. On the larger branches only 

 the outer layer of bark was dead. Scattered all over the dead 

 areas were Ctjtospora pycnidia filled with multitudes of small, 

 colorless spores and, generally, no other fungus was present. 

 The Ci/tospora appears to be parasitic, but positive proof is 

 lacking. 



When the subject of apple canker as it occurs in New York 

 State is thoroughly understood we believe it will be found that 

 there are at least three distinct diseases, which although strik- 

 ingly similar in their gross characters are yet sufficiently dif- 

 ferent to make it possible for an expert to distinguish them 

 without the aid of a microscope. Of the three kinds of canker 

 the Sphceropsis canker is undoubtedly the most important and 

 the Ci/tospora canker the least important. 



Crown Gall. — So far as the apple is concerned, crown gall is 

 confined chiefly to the young trees in the nursery. In this dis- 

 ease rough, spongy, roundish galls occur on the roots. They 

 are usually found at the crown, but may occur on any part of 

 the root system. They are of all sizes up to that of a fist. The 

 nature of crown gall is not well understood. According to 

 Toumey^^ similar galls occurring on the roots of the almond in 

 Arizona are caused by a slime-mold closely related to the fungus 

 which causes the club-root disease of cabbage and allied plants. 

 Crown gall should not be confused with apple-root galls caused 

 by the woolly aphis. Woolly aphis galls are smaller, smooth, 

 hard and generally elongated rather than round. 



We find crown gall not uncommon on apple trees in the nur- 

 series in Western New York, but we know of no case where it 

 has caused material loss. Usually nurserymen discard the 

 worst affected trees. We would recommend that all trees show- 



" Tourney. J. W. An Inquiry into the Cause and Nature of Grown Gall. 

 Arizona Agr. Exp. Sta., Bui. 33. 



