BY D. McALPINE. 231 



finally an irregular rupture takes place, and the frayed margin of 

 decayed tissue usually remains, without any attempt at a healing 

 process. It is on the marginal decayed tissue that the perithecia 

 are generally produced, and soon this falls away in shreds and 

 patches, carrying the perithecia with it. The process of healing 

 seems to have been developed in the tissue of the leaves of stone- 

 fruit trees, because they are so peculiarly susceptible to the 

 fungus. While the leaves of the Apricot-tree are riddled as if 

 with shot, the Apple-leaf is not generally much affected, and the 

 disease is not considered serious, nor generally observed by the 

 orchardist. There may be some peculiar delicacy and suscepti- 

 bility about the genus Prunus, especially when grown under 

 Australian conditions, which causes it to respond readily to any 

 injury, independent of the particular species of fungus concerned 

 in it. In the Apricot this particular fungus causes "'brown spot" 

 of the branches, " shot-hole " of the leaf, and •' scab " of the 

 fruit, while it is only as yet known on the leaf of the Apple, 

 causing leaves here and there to be ruptured in spots, or large 

 brown patches to be formed towards the centre. There is an 

 Apple-tree growing in my garden beside an Apricot-tree, and while 

 it is difficult to find a leaf unaffected in the latter, it requires careful 

 searching to detect a single leaf of the Apple with the fungus 

 upon it. 



Summary. 



There are at least 20 known species of fungi associated with 

 the shot-hole of stone-fruit trees belonging to the Sphaeropsides 

 and Hymenomycetes, with the exception of one {Gnomonia circum- 

 scissa), which belongs to the Pyrenomycetes, and is the higher 

 stage of one of the imperfect fungi {Ascochyta chlorospora). There 

 are at least 10 species associated with "shot-hole" in Australia, 

 the chief of these being, as far as Victoria is concerned, Phyllo- 

 sticta prunicola with its conidial stage Clasterosporium amygda- 

 learum ; and Gnomonia circumscissa with its conidial stacre 

 Ascochyta chhrospora. 



The shot-hole effects in stone-fruit trees are variously explained. 

 Tubeuf considers that the mycelium of the fungi concerned 



