THE RL'ST.S OF .\()\ A SCOTIA. — FHASEH. 385 



iiitV'ctioii takes i)Ia('C. Manv grasses are attacked by this rust^ 

 ai)fl -nine (il)s('r\-(rs ha\c thought that the mycelium may 

 siirvixc rile wiiittn- in these grasses, and that infection of the 

 grain cniii^ may cunie from this sonrce in the spring when 

 n7'ed(i-|ii>i('s ;ii'e prdilnced. However, artificial infection experi- 

 nients iudiciiie ihat few of the grass rusts will grow on wheat 

 or other grains. The i-nsts on the various species have become 

 adapted to their ])artieidar host ami will not usually grow on 

 other species. 



Lirrle can be done to condjat this rust. Varieties that ripen 

 early are not usually so badly affected, so early sowing and the 

 sowing of early varieties would be advantageous. Some varieties 

 are more susceptible than others ■ and attention is now being 

 given ]>y plant breeders to the production of rust proof varieties. 

 It is ])robable that much may yet be accomplished along this 

 line. The barberry which is sometimes grown in hedges should 

 be destroyed as it ])robably fonris n bridging host between the 

 various s]>ecialized forms on the grasses. 



'idle crown iMist of oats ( I'ucrinta Lolii) is very common on 

 the oat abont Pieton and must do much injury to the crop. It 

 is fonnd (tnly on the oat and can be easily distinguished from 

 the stem rnst. as the telia remain covered by the epidermis an 1 

 occni' only on the leaves and sheaths. The aecial stage is found 

 on the l)n(d<tliorn. an introdnced tree or shrid") which is rather 

 common along some roadsides nenr Pieton. Iliis may account 

 foi- the pi'exalence of the rnst as these trees showed a rather 

 jtrononiiced infection in the springs of 1900-10. !Ro control 

 measures are known, but tlie destruction of the ae(Mal lio-t. 



The bi-own oi' co\-ered rust of wheat, riirriiiia Irifirina, is 

 (piite common aiiont Pieton. The telia are iismdly formed 

 on tile lower side n\' ilie lea\'es. They are blacdc in color and 

 remain co\-ered by tlie epidei-mis. This rust usually passes in 

 Americ-i under the name /'iircniKi riihif/o-f'ra or P. riihif/o- 

 rcfit Irilifl. It- svst(^matic jiosition is somewliat unsettled, and 

 its aecial sta'zc somewliat doubtful. 



