APPLE DISEASES 
are mature, pinkish masses ot spores 
exude. The spores from cankers cause 
much of the early intection of fruit on 
the tree each year. 
Myxosporium Canker 
The fungus causing this disease has 
been much confused in the past with 
Sphaeropsis malorum. The two are en- 
tirely distinct. So far as observed the 
damage which it does is confined to kill- 
ing outer portions of the bark on old 
limbs and the killing back of the bark 
on younger limbs and twigs rather than 
to the production of true cankers. On 
such branches the fruiting pustules are 
found on the part which was first killed. 
The dead bark is separated from the 
healthy bark by a sharp line and is 
sunken. The appearance of these branches 
is very characteristic and they can be 
recognized by one who has become some- 
what familiar with the various cankers 
and twig blights, without microscopic 
examination of the fungus. There is 
some reason to believe that the fungus 
is not a very active parasite and it may 
be possible that such diseased branches 
have been injuriously affected by some 
other agency before the attack of this 
fungus. 
Coryneum and Phoma Cankers 
In the examination of apple cankers 
the spores of Coryneum folticolum and 
Phoma mali have been found of quite 
frequent occurrence. Inoculation experi- 
ments have proved that both of these 
fungi were capable of causing disease of 
healthy bark of apple branches. For a 
detailed account of the study of these 
fungi the reader is referred to Bulletin 
170 of the Maine Station. 
Cytospora Canker 
A. species of Cytospora has frequently 
been found on small branches which 
have been killed back but no true 
cankers have been seen. Those lesions 
observed have much the same appear- 
ance aS has been described for branches 
on which Myxosporium is found. After 
a little experience one can distinguish 
the two fungi on the bark without the 
aid of the microscope. 
457 
Pear Blight Canker 
The canker of apple trees caused by 
the pear blight organism, Bacillus amyl- 
ovorus (Burril) DeToni., has been re- 
ported as causing a great amount of 
damage in apple orchards in various 
states. 
See Pear Blight under Pear. 
W. J. Morse, 
Orono, Maine. 
Cuiusp Tre. See Rosette. 
Collar Blight 
A form of pear blight attacking the 
apple at the thickened portion of the 
tree just above and below the ground 
line. 
See Pear Blight under Pear. 
Some forms of collar disease are the 
result of winter injuries followed by the 
entrance of fungus disease. 
CoLttag Rot PuHaAse 
Pear. 
See Blight under 
Core Decay of Baldwin 
A core decay of stored apples was in- 
vestigated by H. J. Eustace, of the New 
York Experiment Station, in 1903. This 
decay occurred quite generally in Bald- 
wins but was not confined to that va- 
riety. 
The apple shows decayed tissue about 
the core, which is brown, dry-rotten and 
tasteless, but surrounded by healthy 
tissue. 
The trouble was not traced to any 
fungus or bacterium. It appeared under 
a variety of soil conditions. The Bald- 
wins that year overbore and storage 
conditions may have been responsible 
for a part of the trouble, as only com- 
mon storage apples seemed to be affected. 
Crown Gall 
Bacterium tumefaciens 
H. P. Barss 
Crown gall is a very common and 
widespread disease known under a vari- 
ety of other names such as “galls,” 
“tumors,” “root knot,” “crown knot,” 
“woolly knot,” “hairy root,’ etc. It has 
been reported from every state in the 
Union and from Canada, Europe, Africa 
and Australia as well. It attacks the 
apple, prune, peach, cherry, raspberry 
