APPLE DISEASES 
Fiom these cankers the spores 
are washed by the rains over the young 
fruits, causing their infection. The 
spread of the disease may often be 
traced to its source by the conelike in- 
fected area, with the canker at the apex. 
Alwood, of the Virginia Station, claims 
that infection sometimes takes place 
without the presence of cankers, and he 
thinks that mummy fruits are the prin- 
cipal source of primary infection. In 
the publications, both of the Illinois Sta- 
tion and the Bureau of Plant Industry, 
the authors recommend cutting out the 
cankers and thorough spraying of the 
trees with Bordeaux mixture, but Al- 
wood advises caution in pruning, unless 
it can be done without material injury 
to the tree. 
Marked differences in susceptibility of 
varieties to bitter rot have been noted. 
While no list can be given that will 
apply to all regions, yet in general the 
Yellow Newtown or Albemarle Pippin, 
Rhode Island, Willow, Huntsman, North- 
ern Spy, Ben Davis, York Imperial, 
Grimes, and Winesap are subject to the 
disease almost in the order of enumera- 
tion, the Yellow Newtown seeming to be 
most liable to serious loss 
Certain conditions of weather influ- 
ence the spread of the disease. It is 
favored by a hot, moist temperature, the 
fungus being very dependent upon the 
combination of high temperature and 
moisture for its development. During 
cool, dry summers little of the disease 
may be expected, and an outbreak may 
be checked if the mean temperature falls 
to and remains at or below 70 degrees 
Fahrenheit for a few days. 
W. M. Scott, of the Bureau of Plant 
Industry, * gives an account of spraying 
experiments for the control of the bitter 
rot on apples. These experiments were 
carried on in 1905 on an orchard of 
Yellow Newtown or Albemarle Pippin 
trees in Virginia, and the conditions 
that season were so favorable for the 
development of bitter rot, as was shown 
by the large number of decayed fruits 
*U. S. Department of Agriculture, Bureau of 
Plant Industry Bulletin 93 
447 
on unsprayed trees, that the conclusions 
aie believed to be of general applica- 
tion The Bordeaux mixture used in 
the experiments was composed of five 
pounds of copper sulphate, five pounds 
of lime, and 50 gallons of water. It is 
Shown that bitter 10t can be controlled 
by four applications of Bordeaux mix- 
ture if applied at the proper times and 
in a thorough manner’ The first appli- 
cation should be made about five or six 
weeks after the trees bloom, followed by 
others at intervals of about two weeks. 
By this method the experimenter was 
able to save from 93 to 98 per cent of 
sound fruit on the trees, while on ad- 
joining trees that were not sprayed the 
fruit was a total loss. In dry, cool sea- 
sons the intervals between the later 
Sprayings may be increased, while in 
hot, moist summers the intervals should 
be shortened and the number of appli- 
cations increased. If for any reason the 
Spraying is not begun until after the 
bitter rot has made its appearance on 
the young fruit, the trees should be 
given at intervals of only a few days 
two thorough sprayings, to be followed 
by applications as described above. 
By beginning the spraying with the 
swelling of the buds and following at 
intervals of about two weeks until about 
eight applications have been given the 
trees, attacks of apple scab, leaf blotch, 
and sooty mold may also be prevented. 
7TCompiled from Illinois Station Bulletin T7. 
Circulars 58, 67: Virginia Station Bulletin 
142; U. S Department of Agriculture, Bureau 
of Plant Industry Bulletms 44, 98 and Farm 
Bulletin 267. 
Black Heart 
The cause of this disease of the trunk 
is obscure. It may be due to too low a 
winter temperature, and again it may 
be the effect of the earliest invasion of 
fungal filaments. Possibly it is the re- 
sult of some other general causes. 
Black Rot, Canker, and Leaf Spot 
Sphaeropsis Malorum Berk. 
The three diseases given above have 
been found to be due to a single fungus, 
“Sphaeropsis Malorum.” The black rot 
of the apple is very common in New 
