442 ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
study many of the results of previous 
workers have been confirmed and some 
important points added to our knowledge 
of the life history of the causal fungus. 
Early in the work a search was made 
for a possible ascogenous stage in the 
life history of the fungus. In November, 
1909, while studying the characters of 
“two year old” cankers, that is;.cankers 
resulting from infection in the fall of 
1907, the apothecia of a discomycete be- 
longing to the family Mollisiaceae 
were found occupying the position of the 
acervulus of the previous season (1908). 
(See Fig. 1-B.) Careful search revealed 
the fact that the apothecia of this fun- 
gus were nearly always found in the 
dead bark of cankers one year after the 
development of the conidial stage. The 
writer has had this fungus under ob- 
servation now for four seasons and has 
never failed to find it in the bark of 
cankers two years after infection in any 
orchard in which he has searched at the 
proper season. No other ascomycete has 
been found at all constantly associated 
with the cankers. We have also ob- 
served the same discomycete in the old 
bark of cankers on pear trees. 
Cultures obtained by most. careful 
methods from the germinating ascos- 
pores were used to inoculate healthy 
Spitzenburg apple trees. In all cases 
cankers resulted which were character- 
istic of apple tree anthracnose. The in- 
oculations were made on December 12, 
1910, and in September, 1911, nine 
months after the inoculation, cankers 
resulting from the inoculation were ex- 
amined and found to bear the typical con- 
idia of this disease. In this way it was 
proven that the fungus found in the old 
cankers was the perfect or ascogenous 
stage of the imperfect or conidial fungus, 
Gloeosporium malicorticis. This ascomy- 
cete was found to be undescribed and the 
name Neofabraea malicorticis (Cordley ) 
was given to it by the writer (1913). 
The economic importance of the discov- 
ery of this perfect stage lies in the fact 
that it proves that the old cankers are a 
source of infection, as well as the new 
cankers. It has also been shown that 
occasionally conidiospores are also de- 
veloped on these same cankers, around 
the edges of the apothecia of the perfect 
stage. We have also determined that 
conidia may be developed in the bark of 
cankers three years after infection. 
Kinds of Trees Affected 
The disease was first recorded on the 
apple, and for some time the fact of its 
occurrence on other hosts was not ob- 
served, or at least did not attract atten- 
tion. Lawrence (1904) was the first to 
record the occurrence of the disease on 
the pear. He also produced the disease 
by inoculation on this host. Cate (1908) 
was first to record the disease upon the 
Fig. 3. 
Cankers on Pear Branches. 
quince. It has since been found to de- 
velop abundantly upon the quince, though 
recent developments indicate that. the 
fungus on that host may be due to a dif- 
ferent species. It has been found not un- 
common on the pear, particularly on the 
Winter Nelis, though it is not to be con- 
sidered a common or serious pear disease. 
On account of the fact that the disease 
under discussion is confined almost en- 
tirely to the Pacific Northwest, it has been 
assumed by a number of investigators that 
there was a native host on which the 
fungus occurred previous to the intro- 
duction of cultivated fruit, and that when 
the apple was introduced into the North- 
