228 THE " SHOT-HOLE FUNGI OF STONE-FRUIT TREES, 



examination, it was found that the rust-fungus was responsible 

 for the effects, although it had not been previously known to act 

 in that way. 



This fungus has become so well established in Australia, owing 

 to the climatic conditions being peculiarly favourable to its develop- 

 ment and spread, and its effects have become so intensified 

 season after season, that now instead of merely causing the tissue 

 of a leaf to become yellow in spots, it causes these spots to drop 

 out, and the tree protects itself by limiting the area of operations 

 as much as possible. The cumulative effects of fungi year after 

 year may lead to startling results, and in the case of this particular 

 rust, not only does it occur on the leaves of stone-fruit trees as in 

 the older countries of the world and occasionally on the upper 

 surface, but also on the branches and fruit, causing considerable 

 damage to the latter. So the extension in spread is often accom- 

 panied by an intensity of action which is more destructi^'e to the 

 tissues than formerly. 



Distribution of the "Shot-hole" Fungi in Australia. 



I have only had an opportunity of examining specimens from 

 certain parts of the Commonwealth, and therefore only a limited 

 view can be taken of the distribution, but there are sufficient data 

 to show that the nature of the climate is the great determining 

 factor in the distribution of the species. 



Around Melbourne and south of the Dividing Range in 

 Victoria I found the prevalent forms to be C. amygdalearum and 

 P. prunicola; but in the Goulburn Valley and the drier districts 

 of Victoria it was A. chlorosjiora and G. circumscissa, together 

 with Exohasidium vitis. 



In South Australia, C. amygdalearum and P. prunicola were 

 the common forms, with P. perslcoi occasionally. 



In Queensland, in the neighbourhood of Brisbane, Cercospora 

 circtcmscissa was determined by Massee on Peach-leaves, and this 

 is the only State in which it has been recorded. This is the 

 great "shot-hole" fungus of California, especially in the coast 

 regions, on account of the frequent fogs and the general humidity 



