PATHOGEN r ICITY OF H. SATIVUM 



necessarily been obtained in these studies. On the basis of spore 

 shape and similarity with the organism obtained from typical spot 

 blotch lesions and the ability to produce spot blotch symptoms on barley, 

 the organism undoubtedly should be included in the species Helmin- 

 th osporium sativum P.K.B. 



Z.-40- 



00. 



60 



20 



80 



/e c 



24- C 

 2.8 C 

 32 C 



!\ 



1-t 



\ 



2O 



60 



/OO 



/2O 



Lengfh of spores (microns) 



Fig. 2. Length of Spores of Helniinthosporinm satii'itin Produced on Potato Dextrose Agar 

 . at Various Temperatures 



The shape of the spores was found to be more or less the same 

 under various conditions. At 24 and 28, the spores tended to be 

 fat, spindle-shaped to broadly elliptical, sometimes slightly curved. 

 At 32 the thickening in the middle was less evident, and they tended 

 to be more uniform in diameter. The small spores were globose to 

 ovate. At 14 the longest spores were mostly narrowly cylindrical. 

 There was a marked tendency for the thickened portion to occur 

 nearer the base than the apex, giving the spore the shape of a slender 

 flask. 



