BY D. McALPINE. 445 



The abo\e table shows that it is not a mere matter of moisture 

 which settles the greater or less prevalence of the disease, but 

 other conditions, such as accompanying heat or cold, will also 

 influence it. 



Generally the spores are plentifully produced about the 

 beginning of the year, and the leases have usually all dropi)ed off 

 by April. It is very noticeable how the leaves fall away from 

 the lower ends of the branches, leaving only a small tuft of leaves 

 at the top, wdiich ma}^ be regarded as the expiring effort of nature 

 to renew the foliage of which the tree is prematurely deprived 



Hosts and Parts Attacked. 



I have found the fungus in Victoria on the leaves of the peach 

 and its smooth-skinned variety the nectarine, the j^lum, the 

 apricot and the almond. It is most prevalent on the plum and 

 peach and comparatively rare as yet on the apricot and almond. 

 In other parts of the world the disease is found on other species 

 of Prunus. In California it attacks the cherry in addition to the 

 above, and in the old world it is found on the sloe or blackthorn 

 ( I'runus i<pinosa^ and other species. Although this fungus has 

 only been know^n elsewhere to attack the leaves, I had a specimen 

 sent from AVangaratta in which the fruit was ' affected. It was 

 ver}'- noticeable that only one side was attacked, and presented 

 the appearance of a number of pimples or blisters of a brownish 

 colour. The fungus was evidently not so far advanced as on the 

 leaves, so that the conspicuous rusty colour was not so apparent. 



In South Australia the disease has been found on the peach, 

 plum, apricot and almond leaves, as well as on the fruit of the 

 apricot. The latter specimen was kindly sent to me by J. G. O. 

 Tepper, F.L.S., for determination, and he was naturally surprised 

 to find the leaf-rust become a fruit-rust. It is rather peculiar 

 that no previous record of such a comparatively common rust 

 should be known on fruit outside of the Australian colonies, but 

 it only shows what a glorious climate we have for luxuriant 

 growth, that of fungi included, and it points to the grave danger 

 of allowing fungus pests to run rampant, for they may attack 



