New YorK AGRICULTURAL EXPERIMENT STATION. 843 
regarded usually by them as being the result of sun scald, or as 
a condition peculiar to the growth of certain varieties of apple 
trees. It was only necessary, however, to call the attention of 
orchardists to the disease and to make known its appearance 
and effect, when it was recognized and found to be a serious 
pest in most of the apple-growing sections of the State. 
While the bulletin above mentioned gives the results of two 
years’ work with the fungus, it is incomplete; since many ques- 
tions arose that could not be answered. The work was con- 
tinued through the season of 1900 and a few more facts were 
established which add to our knowledge of the disease.. 
EFFECTS OF THE DISEASE AND APPEARANCE OF 
AFFECTED PARTS. 
iA brief discussion of the work of the fungus and the appear- 
ance of cankered limbs will not be out of place at this time; but 
for a fuller discussion of the subject the reader is referred to the 
former bulletin. 
Any part of the trees above ground, with the possible exception 
of the leaves, may be attacked by the canker fungus which has 
been proven to be Spheropsis malorum Pk. When the larger 
limbs, or in rarer instances, the trunks, are attacked, the inju- 
ries are known as cankers. Such injuries are often quite con- 
Spicuous since the bark becomes thick and rough, and saprophytic 
fungi soon gain a foothold causing the parts to turn black. (See 
Plate LUI.) The injuries are often several feet in length; and 
because of these striking characters, cankered limbs may be 
recognized at a considerable distance. 
The fungus may live in the outer bark, but here it does little 
harm, and true cankers are formed only when it gains entrance 
to the cambium layer. Under favorable conditions the fungus 
spreads until a considerable area of bark is destroyed. The limb 
may be girdled by the fungus, but borers and saprophytic fungi 
often complete the work of destruction. An affected branch 
may live for a number of years and bear fruit, but if the wound 
