APPLE DISEASES 
sometimes the trunk In some cases it 
seems to cause merelv a greater rough- 
ening of the bark, but where a broken 
twig or other injury furnishes an en- 
trance to the actively growing tissue of 
the host the effects are often much more 
pronounced. In serious cases the bark 
may be killed over considerable area 
and become conspicuously cracked and 
roughened (Fig. 1). It is set off from 
the living bark by a very definite bound- 
ary. Limbs are often so nearly girdled 
that the parts beyond die Pyenida 
similar to those on the fruit are found 
on the canker. 
Like the other diseases attributed to 
Sphaeropsts Malorum, the leaf spot is of 
general occurrence. The disease makes 
its appearance on the leaves’ shortly 
after they unfold from the bud. Infec- 
tion continues throughout the spring, 
but notes taken the past two years in- 
dicate that it is uncommon after the 
middle of June. At first the spots are 
small, purple areas, but as growth pro- 
gresses they become yellowish-brown in 
color and attain a diameter of from one- 
eighth to one-half inch (Fig.1). They 
are quite uniformly circular in outline. 
The margins are somewhat elevated, giv- 
ing to the spot a sunken appearance. As 
the spots become older a _ secondary 
growth may spread from the central 
affected area, producing a somewhat ir- 
regular blotch in which the outline of 
the original spot can always be recog- 
nized. (See Fig. 1.) It often happens 
that several of these areas become con- 
fluent, and thus the greater part of the 
leaf may become affected. Spotted leaves 
fall from the trees early in the fall and 
their working efficiency is always greatly 
reduced by the middle of the summer. 
Trees thus robbed of their foliage from 
year to year must eventually become 
greatly impaired in their vigor. 
The cause of the leaf spot has occa- 
sioned no little difficulty. A number of 
fungi have been found to be present in 
the spots, but inoculation experiments 
have indicated that Sphaeropsis Malorum 
is probably the only one that is of im- 
449 
portance in the production of the dis- 
ease. 
Treatment 
The fact that one fungus is responsible 
for three different forms of disease 
makes its destruction a matter of special 
importance and rather unusual difficulty. 
Spraying has been quite effective in con- 
trolling the leaf spot. In the summer 
of 1908 the per cent of leaves spotted 
in the orchards referred to under apple 
scab was reduced from 97 to 26 by the 
use of Bordeaux and to 21 by the use 
of lime-sulphur solution. Five sprayings 
were made, but it is probable that only 
the first three were effective for leaf 
spot. Sprayings made at various times 
in the summer have had little or no 
effect upon the number of spots of rot 
on the fruit at picking time. The de- 
struction of the affected fruit seems to 
be the most efficient treatment for this 
form of disease. All cankered limbs 
should be cut out and burned. Large 
wounds should be protected by a cover- 
ing of paint. Thorough spraying is of 
value in protecting the limbs. Heavy 
applications made when the trees are in 
a dormant condition are probably espe- 
cially efficacious. 
CHARLES BRrooKS, 
Durham, N. H. 
Blackspot Canker or Apple Tree 
Anthracnose 
Neofabraea Matlicorticis (Cordley) 
Jackson 
By W. H. LAWRENCE 
Plant Pathologist and Horticulturist for 
Hood River Apple Growers, Hood 
River, Oregon 
More than a decade has passed since 
Blackspot Canker or Anthracnose made 
its appearance in apple orchards through- 
out the Pacific Northwest and became so 
destructive that information concerning 
its control was sought. Although the 
cause and control of the disease has been 
determined and fully demonstrated the 
disease has been allowed to continue year 
after year in some of the orchards of 
each of the apple-growing sections. Con- 
tinuous and scattering observations as 
