386 TIIK KfSTS OF NOVA SCOTIA. I'lJ ASFIt. 



Till' liiiiotbv rust only ])Ogaii to attract attention in North 



America a. few years ago. Ft seems to be rapidly increasing'. 



Some i-eg'ard it as identical witli the stem rust of wheat, while 



others regard it as a distinct s))ecies with unknown aecia. In 



gross and niier()Sco])e apjKjarance it cannot be distinguished 



from the stem I'ust of wheat. Tt is quite common on the timothy 



about Pictou, especially on timothy about roadsides and fences 



that has not been cut at the harvest season. It seems to be 



increasing so rapidly that there is danger that it may become 



a pest, but the early maturing of the hay ci'0]i may ])revent any 



serious damage. 



Red Clover Rust: The uredinial and telial stages of clover 



rust {Uromyces Irifolii) is common on the leaves of clover iu 



the fields of Pictou. They appear as brownish ])o\vderv spots 



on. the under surface of the leaves and on the stems. The 



aecial stage is unknown. It is said to do little damage to the 



early crop, but the atta(;k on the second crop is more severe. 



Control is unneces-nry. and no ])revenJtative measures are 



known. 



( 'l(issific'ifi'>ii. 



The classitication of the rusts presents many ditficulties 

 owing to the \aiiable number of forms and the heteroecism of 

 many species. Besides, rusts that cannot be distinguished 

 morphologically have become specialized or show i^hysiological 

 ilifferences in the choice of their hosts, and botanists are not 

 agreed as tf) the classification of these. Some regard them as 

 separate species, while others would ])lace them as simply 

 physiological species or form species. The classification is 

 likely to remain unsettled until they are more fully studied 

 and their life histories and relations to their hosts more com- 

 ]»letely known. 



The rusts are rc^garded by most botanists as belonging to 

 the class Basidiomycetcff on account of the germinating telio- 

 spore producing four basidia which either remain within the 

 ^pore cell or are V)rne in the air on a short ]>romycelium. each 



