214 



RESEARCHES ON FUNGI 



There are two species of Tilletia 1 which cause bunt of wheat in 

 Western Canada and the United States of America : T. tritici and 

 T. laevis. T. tritici is distinguished from T. laevis by having the 

 walls of the chlamydospores reticulated instead of smooth. 



There is a considerable amount of variation in different strains 



of both Tilletia tritici 

 and T. laevis in respect 

 to the amount of stunt- 

 ing of the host plant, 

 the shape of the bunt 

 balls, the production 

 of trimethylamine, and 

 pathogenicity for differ- 

 ent host plants. 



In 1931, Roden- 

 heiser, 2 from experi- 

 mental data, concluded 

 that the difference in 

 the relative degree of 

 stunting of the host 

 plant varies with differ- 

 ent strains of the same 

 species and cannot be 

 generally accepted as a 

 criterion for separating 



Fig. 104. — Bunted grains (bunt-balls) of Durum 

 Wheat parasitised by Tilletia tritici. Those on 

 the left are intact, while the others are shown 

 in median-longitudinal or in transverse section. 

 The dark chlamydospores, which have an 

 unpleasant odour, fill the whole of each grain's 

 interior. Photographed by I. L. Conners at 

 the Dominion Rust Research Laboratory at 

 Winnipeg. Much enlarged. 



T. tritici and T. laevis. 3 



Potter and Coons, 4 in 1918, found that the bunt balls of Tilletia 



tritici are rounded-oval, whereas those of T. laevis are elongated. 



Hanna 5 grew a strain of T. tritici and a strain of T. laevis side by 



1 The genus Tilletia was so named by Tulasne in 1847 in honouf of the Abbe 

 Tillet. 



2 H. A. Rodenheiser, " Stunting of Wheat caused by Tilletia levis and T. tritici,'" 

 Journal of Agricultural Research, Vol. XLIII, No. 5, 1931, pp. 465^468. 



3 Dr. O. S. Aamodt of the University of Alberta has informed me in litt. that 

 he has obtained results from greenhouse and field experiments which confirm those 

 of Rodenheiser. 



4 A. A. Potter and G. H. Coons, " Differences between the Species of Tilletia 

 on Wheat," Phytopathology, Vol. VIII, 1918, pp. 106-113. 



5 W. F. Hanna, personal communication. 



