PATHOGENICITY OF H. SATIVUM 



The plates were inoculated in the center and incubated at the various 

 temperatures. Each series was run in triplicate. The diameter of the 

 colony was taken as the index of growth. In some cases it was impos- 

 sible to control the temperature within several degrees, so that one series 

 can not be checked quantitatively against the other. Different lots of 

 potato dextrose also were used in the different series. The results of 

 two series are given in Table V. In each case, the size of the colony 

 represents the average of three plates. 



TABLE V 



EFFECT OF TEMPERATURE ON GROWTH OF Helminthosporium sativum on Potato Dextrose Agar 



Temp erature ( Cen tig rade) 



O 5 /O /S 2O 



35- 



Fig. 4. Growth of Hclminthosporinm sativum on Potato Dextrose Agar in Petri Dishes 

 The curve represents the diameter of the colonies at the end of seven days. 



Data obtained in the second series are shown graphically in the 

 curves of Figures 4 and 5. Figure 4 shows the relative growth of 

 the fungus at the various temperatures after seven days. Figure 5 



