CULTURES OF HETEROECIOUS RUSTS IN 



1918 



W. P. Fraser 



While making a field survey in western Canada of the rusts 

 which attack cereals, a number of grass and sedge rusts were 

 collected, and a few cultures which field observations suggested 

 were undertaken. These cultures were carried on in a well- 

 lighted room in the Dominion Laboratory at Brandon, Man. 



The methods of inoculation were those commonly employed. 

 When teliosporic material was used it was placed in a moist 

 chamber until the teliospores were germinating, when it was sus- 

 pended above the plants used in the cultures. The plants and 

 teliosporic material were then sprayed with water by means of 

 an atomizer and covered with a bell jar for about 48 hours. 

 When aesciosporic material was used the fresh aesciospores were 

 transferred with a flat needle to the leaves of the culture plants 

 and in addition the parts bearing aecia were suspended above so 

 that the aesciospores would fall on the plants used in the culture. 

 They were then sprayed and covered with a bell jar as in the 

 case of the teliosporic experiments. Checks were kept which in 

 all cases remained free from infection. 



Uromyces Alopecuri Seym. 



Aecia on Raniincuhis Macoiinii Britton were often found as- 

 sociated with this rust on Alopecurus aristiilatits Michx., so that 

 the connection of the aecia was clearly indicated. On June i6th, 

 two pots of Alopecurus aristiilatits and one each of Agropyron 

 tenerum Vasey and Hordeum juhatum L. were inoculated with 

 fresh aeciospores collected at Brandon, Man. Uredinia began to 

 appear on the pots of Alopecurus on June 23, and eventually 

 aeciospores developed abundantly, followed later by telia. There 

 was no infection of the other grasses. Collections of aecia were 



129 



