482 



DISEASES OF CULTIVATED PLANTS 



fragments. On the other hand, if warm weather is suddenly 

 followed by a chill, conidia are produced in abundance. The 

 disease may appear during any period of the growth of the 

 host. 



Conidiophores gregarious or subfasciculate on large, dry, 





I i'.. 144. Helminthosporium turcicum. 1, portion of a 

 maize leaf with fungus; 2, a cluster of conidiophores, two 

 bearing conidia, highly mag. 



brownish spots, septate, 1 50-1 Sox 6-9 ji ; pale olive, apex 

 almost colourless, often nodulose; conidia spindle-shaped, 

 ends acute, 5-8-septate, pale olive, 80-140X 20-26 ft. 



A difficult disease to check, perhaps burning the stubble 

 after corn has been gathered, it' practicable, would to a certain 

 extent prevent future infection. Rotation of crops, however, 

 would be the most certain method, and as maize impoverishes 

 che soil to a great extent, this course is advisable. 



Bancroft, Proc. Roy. Soc. Queens/and, 8, p. 108. 



Helminthosporium teres (Sacc.) sometimes proves destruc- 

 tive to the barley crop, causing the leaves to shrivel and die. 

 It forms rather large olive blotches on the leaves. 



