336 THE RUSTS OF NOVA SCOTIA. FRASEH. 



The timothy rust only began to attract attention in North 

 America a few years ago. It seems to be rapidly increasing. 

 Some regard it as identical with the stem rust of wheat, while 

 others regard it as a distinct species with unknown aecia. In 

 gross and microscope -appearance it cannot be distinguished 

 from the stem rust of wheat. It 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 crop may prevent any 

 serious damage. 



Red Clover Rust : The uredinial and telial stages of clover 

 rust (Uromyces trifolii) is common on the leaves of clover in 

 the fields of Pictou. They appear as brownish powdery 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 attack on the second crop is more "severe. 

 Control is unnecessary, and no prevenlta.tive measures are 



known. 



Classification. 



The classification of the rusts presents many difficulties 

 owing to the variable number of forms and the heteroecism of 

 many species. Besides, rusts that cannot be distinguished 

 morphologically have become specialized or show physiological 

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

 agreed as to the classification of these. Some regard them as- 

 separate species, while others would place 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- 

 pletely known. 



The rusts are regarded by most botanists as belonging to 

 the class Basidiomycetes on account of the germinating telio- 

 spore producing four basidia which either remain within the 

 spore cell or are borne in the air on a short promycelium, each 



