176 REPORT OF THE BOTANIST OF THE 
sharply defined and of various 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 Cytospora pycnidia filled with multitudes of small, 
colorless spores and, generally; no other fungus was present. 
The Cytospora 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 Spheropsis canker is undoubtedly the most important and 
the Cytospora canker the least important. 
Crown Gautu.—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- 
*Toumey, J. W. An Inquiry into the Cause and Nature of Crown Gall. 
Arizona Agr. Exp. Sta., Bul. 33. 
