i8 



TECHNICAL BULLETIN 17 



shows the daily rate of growth at each of the temperatures tested. 

 Plate I shows the final appearance of the colonies in the first series, 

 Plate II in the second. 



From these results we may conclude that the minimum temperature 

 for the growth of Helminthosporium sativum lies near 0-2 C., the 

 maximum temperature between 35 and 39 C. and the optimum be- 

 tween 24 and 28 C. 



28 C 



2^ c 



Fig. 5. Daily Rate of Growth of Helminthosporium sastivum on Potato Dextrose Agar in 



Petri Dishes 



