SCIENTIFIC COMMITTEE, NOVEMBER 24. 



clxxxi 



" On the Becent Differentiation of the Wheat Mildews. — We 

 are all familiar with what is known to us in Great Britain as the 

 Wheat Mildew par excellence, Puccinia graminis. Curiously 

 enough during the past season (1896) it has been practically 

 absent from our corn fields. The only specimens I have seen 

 have been upon Triticum repens, and on barley. These were 

 only found after careful searching in the immediate neighbour- 

 hood of one of the few barberry bushes growing semi-wild in a 

 hedge a few miles from King's Lynn. Not more than a dozen 

 barley plants affected with the fungus could be found, and they 

 were within a yard or two of the aecidial host plant. During 

 the last year or two Professor Eriksson, of Stockholm, working 

 in conjunction with Dr. E. Henning, has succeeded in eluci- 

 dating the morphology of the fungi which produce the so-called 

 1 rust ' of wheat. Rust, of course, is a collective name applied 

 to any uredo with a yellow or orange colour occurring upon 

 cereals generally. We have hitherto recognised a Puccinia on 

 wheat and other grasses, characterised by the yellow colour and 

 profusion of its uredospores, and have known it as P. rubigo- 

 vera or P. straminis. From the investigations of the above 

 botanists it is clear that there are two distinct and well-marked 

 species confounded under these names. They now call them 

 P. glumarum, Schinn, and B. dispersa, E. and H. 



" Puccinia glumarum is the most important from an economic 

 point of view, as it is apt to attack not only the leaves and 

 sheaths of the wheat plants, but also the glumes, and, as a 

 natural sequence, the grain itself. When this is the case the 

 uredospores constitute the old Trichobasis or Uredo glumarum, 

 and may be readily enough seen by pulling apart the glumes 

 of the affected ears. They look as if a little golden dust had 

 found its way into the ear, some of which adheres to the glumes, 

 while some is dusted upon the young kernel. That the 

 1 rust ' was injurious to wheat when it attacked the ear has 

 been known to agriculturists for long, and it is only under 

 these circumstances that rust does our wheat crops any appre- 

 ciable amount of harm. This rust, it should be remarked, is 

 quite distinct from the rust which does so much injury to the 

 wheat-grower of Australia. To us the injury consists in a 

 dwarfing of the affected kernels which the uredo and its asso- 

 ciated teleutospore cause. On the leaves of the wheat the 



