ISTew York Agricultueal Experiment Station. 337 



On the other hand it is evident that Schizophyllum commune Fr. 

 cannot penetrate living apple-tree bark and it is quite probable 

 that the same is true of pear-tree bai'k. The result of the inocu- 

 lations on the quince cannot be regarded as conclusive because 

 of the small number of inoculations made; but numerous inocu- 

 lations made in the spring of 1899 showed that the dark spored 

 fungus can produce a cankered condition of quince limbs when 

 inserted under the bark. 



The stress of other duties during the growing season prevented 

 any study into the nature of the canker fungus and nothing further 

 was done until fall when cultures of the fungus were shown to 

 Mr. F. C. Stewart, the Station Botanist. He at once noted a 

 strong resemblance of the dark spores to those of the black rot of 

 the apple, Sphaeropsis malorum Pk., and suggested that it might 

 be that disease. Matm-e apples were at once inoculated with 

 material from the test tube cultures that had been obtained from 

 cankered apple-tree limbs. In twenty-four hours decay had be- 

 gun around the points of inoculation and in sixteen days pyc- 

 nidia and mature spores of Sphaeropsis were found on all inocu- 

 lated apples. The check apples which were punctured but not 

 inoculated and kept under the same conditions remained sound. 

 This experiment was repeated many times and the results were 

 always the same. 



l^ow that it Avas known what to look for an examination of 

 cankered limbs in the orchard revealed the presence of an abun- 

 dance of small, dark, fungus pustules or pycnidia on the brown 

 and shi-unken areas of dead bark. Fig. 3 of Plate XXVIII is a 

 larger view of the smaller canker shown in Fig 1 at h. An ex- 

 amination of the bark on the older portion of the cankered area 

 reveals the presence of numerous pycnidia in which the dark col- 

 ored spores, that have been frequently mentioned, ai'e borne. 

 They are sho\vn natural size in Fig. 4, which is a small section of 

 the dead bark from the same canker. It will be seen that the 

 pycnidia are abundant and large enough to be easily found. 



22 



