738 FUNGI 



{e) Cultivate those races and varieties of cereals which are 

 found by experience to have * rust '-resisting powers. 



Races of wheat with upright, narrow leaves and a strong 

 epidermis upon which there is a marked waxy ' bloom,' are 

 generally less easily infected with ' rust ' than those with broad, 

 soft, green leaves. 



Varieties with densely packed ears are usually resistant, 

 though this is not always the case. 



Nursery, Trump, and Squarehead wheats are highly resistant 

 to the disease, while Horsford's Winter Pearl, Hoary White, are 

 almost always ' rusted.' 



9. About 700 species of Pucdnia are recorded on a very great 

 variety of plants. Some of them possess all the spore-forms as 

 in Puccinia graminis, while many produce teleutospores and 

 uredospores, or teleutospores only, .itlcidium-forms are also 

 not uncommon, the teleutospore-forms of which are hitherto 

 unknown. Few species, however, except those mentioned are 

 of practical importance so far as the farmer is concerned. A 

 number attack garden plants, the worst perhaps being the 

 following species, all of which are autoecious. 



(a) P. Malvacearum Mont., which attacks hollyhocks and 

 species of Malva. Only teleutospores are produced by the 

 fungus and they germinate as soon as ripe. 



(^) P. Hieracii Mart., common on many wild Compositae, such 

 as thistles, hawkweeds, and very destructive to chrysanthemums. 

 This species produces teleutospores, uredospores, and spermo- 

 gonia. Hitherto, only the uredo-stage has been observed upon 

 cultivated Chrysanthemums. The 'rust' attacks the young 

 cuttings soon after they have rooted, and appears very exten- 

 sively upon the older plants in late summer and autumn, 

 especially after being brought indoors. 



The disease may be kept in check or completely overcome by 

 spraying with Bordeaux mixture once or twice a week through 

 the summer. The cuttings and old stools of the plants should 



