70 HATCH EXPERIMENT STATION. [Jan. 



lished and killed the tissue. The fungus, like all those 

 causing these diseases, reproduces itself b}^ spores, which 

 are produced in minute cavities in the dead area, usually 

 on the under side of the leaf. Almost all the leaves on 

 affected trees become dotted over with the little dead spots, 

 and most of them fall to the ground before their time, thus 

 weakening the tree. The disease is not, however, an espe- 

 cially destructive one, except to the beauty of the tree. 



A Leaf Spot of the Wild Black Cherry. 

 {Septoria cerasina, Pk.) 



The well-known "shot-hole" fungus, which often causes 

 extensive damage to the plum and cherry, has been exceed- 

 ingly abundant this year upon the leaves of the wild black 

 cherry {^Prunus serotina)^ many trees being almost entirely 

 leafless in August. This fungus attacks the leaves of plums 

 and cherries of several species, producing dead spots upon 

 them, and eventually causing their death. In connection 

 with the wild cherry the disease has little economic impor- 

 tance, except as it may spread from that tree to cultivated 

 species. On this account, the destruction of the wild cherr\' , 

 so desirable for the repression of the black knot and tent 

 caterpillar, is even more advisable. 



