4 2 



Schedule of questions of the Board of Agriculture in 1892 stated 

 that early sown wheats escaped rust more than those which were 

 put in lute. It would seem far more important to get wheat in 

 early in Great Britain, where climate is so mtich colder, and th< 

 winter far more severe than in Australasia. 



SPRING-RUST AND MILDEW ("Puccinia rubigo 



vera"). 



There is much confusion, and most naturally, among culti- 

 vators in all countries where cereals are grown, concerning the 

 two kinds of rusts which attack these crops, especially wheat 

 and oats. It will be useful, therefore, having fully described the 

 summer-rust and mildew^/Z^do linear is, and its forms of Puccinia 

 graminis and JEcidium &. "beridis, to give a detailed account also 

 of the spring-rust, Urefa rubigo vera, and its mildew forms of 

 Puccinia rubigo vera. 



The differences between these two rusts and mildews are 

 sharp and clear, and w r hen once noted they will be easily 

 remembered. In the first place, the spring-rust ( Uredo rubigo 

 vera} often appears as early as March, much earlier than the 

 the summer-rust (Uredo linear is}. The colour of the spring- 

 rust is more yellow and not so red, or orange-coloured, as that 

 of summer-rust. Its son ^r blotches, u L /on the blades- are not 

 quite so large nor so long, being more round in shape, as will be 

 seen by figures i, 2, and 3 of Plate IV.* By comparing the 

 figures of a spring rust sorus, and a section of a sorus highly 

 magnified, and of the spore germinating (Figs. 4 and 5, Plate IV.) 

 with those shown on Plate II. (Figs. 4 and 5) illustrating Puccina 

 graminis, in its uredo stage, a marked distinction will be noticed. 



The sori, of Puccinia rubigo vera (Fig. 3, Plate IV ), are 

 full of spores of a yellow colour, somewhat oval in shape. 

 1 hese spores are constantly discharged i immense quantities 

 upon the plants near them, and carried by the wind in all direc- 

 tions upon corn plants and grasses. They germinate upon 

 suitable hosts by putting forth germ tubes (Fig. 5, Plate IV.). 

 These enter the stomata of the leaves and form new sori, so 

 that there is a continual succession of these uredo spores until 

 autumn approaches, and the corn plants begin to ripen. A 

 change then takes place ; the reddish-yello\v spots become dark- 

 coloured (Figs. 6 and 7, Plate IV.), just as in the case of 

 Puccinia graminis, and the uredo form is gradually merged into 

 the Puccinia or teleutospore form. The sori of the teleutospores 

 are considerably smaller than those of Puccinia graminis, and of 

 a rather lighter colour (Figs. 8 and 9, Plate I V.) . The spores from 

 these sori are also smaller and rather differently shaped, and 

 enveloped in coverings, paraphyses (Fig. i o, Plate IV.). In these 

 states they are actively injurious to the corn plants. Though it 



* The figures of this Plate, as well as those of Plates I. and II., were 

 drawn by Mr. Worthington G. Smith. 



