31 



for planting in game covers, and it may be inferred that other 

 species of Berberis, and of other genera of the Berberidaceaa, 

 are also hosts of the fungus. 



The weak point in the conclusions arrived at by scientists as 

 to the Barberry being the sole host of the secidium form of 

 Puccinia graminis is the fact that in countries where the 

 Berberidaceae are not indigenous, mildew on corn-plants is more 

 abundant and destructive than in Europe. In parts of America, 

 for instance, these shrubs are not known. In the Australasian 

 Colonies, where mildew is fearfully prevalent, they do not 

 occur. In India the barberry is common in the Northern 

 Provinces, but "throughout the plains of India there is no 

 species of barberry, and it is necessary to assume that the wheat 

 plants were attacked by the aecidiospores of the barberry 

 which had been wafted to them from enormous distances. 

 The spores are, however, exceedingly minute, and it is quite 

 possible they may be carried by the winds to such immense 

 distances." * 



The Australasian mycologists are endeavouring to discover the 

 host of the aecidium, which stage has never yet been seen in 

 Australasia.f Dr. Cobb, the pathologist to the New South 

 Wales Department of Agriculture, states this, and at the Con- 

 ference of Australasian delegates at Sydney in 1891, he said 

 that " it was not true that the barberry stage was necessary for 

 rust to go annually through the barberry. The mistake had 

 been made in Australia in assuming this. The facts in a 

 cold country would probably warrant the assertion, but here, in- 

 asmuch as they could find red rust existing all the year round, 

 it followed that it was not necessary at all." 



Mr. D. MacAlpine, of the Victoria (Australia) Department 

 of Agriculture, holds that as the barberry is not indigenous to 

 Australia, and cannot play the host to the promycelial spores, 

 either the red spores can prolong their germinating power in the 

 genial climate, and carry on the life of the fungus from year to 

 year, or there is an unknown plant on which the promycelial spores 

 germinate. Mr. Pearson, another authority, says, some botanists 

 hold that the promycelial spores, which are produced during 

 warm spring weather, and are wafted about in countless 

 numbers not long before the rust begins to show itself on 

 the wheat, alight on the young wheat plants, and if the 

 atmospheric conditions are favourable germinate thereon, 

 entering the wheat tissues through the stomata, and give rise to 

 the red or uredo stage." % 



Plant pathologists in Australia are endeavouring to discover 

 another host than the barberry for the Puccinia graminis, or to 



Rust and Mildew in India, by the late A. Barclay, M.B., F.L.S. The 

 Journal of Botany, vol. xxx., 1892. 



j- Contributions to an Economic Knowledge of the Australian Rusts 

 (Uredineai), by N. A. Cobb, Agricultural Gazette of New South Wales, 

 January, 1892. 



J Appendix to Report of Conferences on Rust in Victoria, 1890, by 

 Mr. A. W. Pearson. 



