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2. Fungi — The second group which contains the gummosis causing 

 fungi is much better studied, and numerous varieties are known, especially 

 (1) the Clasterosporium carpophilum is found on numerous stone fruits. 

 Its presence may be determined in the following manner : 



(a) On the leaves — dead brown spots 1-5 of an inch in diameter. They 

 are distinguished with difficulty from other spots on the leaves, but have a 

 clear centre and a red outline. The spots often fall out of the leaves. 



(b) On the petioles — no characteristic changes can be seen on the 

 petioles, although sometimes small drops of gum may be present. Leaves 

 of which the petioles are badly diseased fall off; the cherry especially is 

 attacked in this way, and the fungus is seldom found on other parts. 



(c) On the branches — especially branches of peach trees one to two 

 years old are attacked. On young wood the spots are round, sunken, 

 brown or blackish-brown, often with a red outline. 



(d) On the fruit — on fruit the disease may appear at any time, and 

 the spots have a red outline. 



This fungus is often mentioned in literature as the cause of holes in 

 leaves of trees in general. 



Another fungus was found in 1903 during an epidemic among the 

 cherry trees along the Rhine. All the infected trees showed much gum- 

 mosis; it was discovered on that occasion that the fungus was unable to 

 attack healthy trees, but penetrated into injuries or wounds and caused 

 the death of a few ceils; once established on these dead parts it pene- 

 trated the healthy bark and wood and often caused the death of the tree. 

 At all seasons of the year large branch systems and heavy trees died 

 suddenly once the fungus had taken possession of them. The dividing 

 line between the living and dead part is very clear and large quantities of 

 gum appear. The growth of the fungus is favored by dry weather. 

 Many other instances are mentioned in which damaged trees are attacked 

 by organisms. For example, the prunus Japonica is often killed by a 

 fungus which enters through small wounds in the bark, broken branches 

 or places where buds of leaves or flowers are broken off. 



Further, I remember an epidemic at an Experimental Station among 

 the two-year old wild cherry trees and the improved cherry trees which 

 were grafted in the crown. 



The bark was dead in several places and large quantities of gima had 

 collected on these spots, where such a ring of gum went all round the 

 trunk the tree died. An investigation showed that the gum was full of 

 bacteria and that the trouble had started at the incision in some dead cell 

 tissue. 



