THE FUNGI WHICH CAUSE PLANT DISEASE 613 



conidia acrogenous, straight, cylindrical, ends rounded, 4 to 5- 

 septate, not constricted, dark olive-brown, 100-115 x 14- 

 18 /*. On oats and barley. 



H. avense Ei. 



Similar to H. teres, but the conidiophores scattered, 150-200 x 

 9-12 n, septate, brown; conidia cylindric, brownish, 4 to 6-septate, 

 80-100 X 15-16 n. On oats. 



The conidia of the two last species infect grains and seedlings. 

 The conidia spread the disease from the early infection centers 

 to other parts of the plants but the mycelium remains local. 



H. bromi Died, on Bromus=Pleospora bromi, see p. 261. 



H. tritici-repentis Died.=Pleospora tritici-repentis, see p. 262. 



H. sativum (P.) K. & B.'"^ 



Mycelium branched, septate; conidiophores fasciculate, fuscous, 

 brown, septate, 8-10 ju wide, sometimes swollen between the 

 septa; conidia solitary, apical, dark brown, 6 to 11-septate, 105- 

 130 X 15-20 UL. 



The cause of a destructive late blight of barley from Iowa to 

 Saskatchewan. The disease manifests itself by dark colored, 

 elongate spots on the leaves. 

 It also occurs on the glumes 

 and spikelets, sometimes even 

 penetrating the grains. 



H. sorokinianum Sacc. is re- 

 ported on wheat and rye in 

 Russia; 



H. tritici Hen. on w^heat in 

 Africa; H. sigmoideum Cav. 

 on rice in Italy; while several 

 species are recorded on bam- 

 boo. 



H. turcinum Pass. 



Spots, large, dry, brownish; conidiophores, gregarious to fascicu- 

 late, septate, 150-180 X 6-9 II, pale olive, apex almost hyaline, 

 often nodulose; conidia spindle-shaped, acute, 5 to 8-septate, 

 pale olive, 80-140 x 20-26 li. 



It produces spots on com and sorghum in Europe and America. 



H. inconspicuum C. & E.^^- ^^^ 



Fig. 413. — Helminthosporium sativum 

 from barley, spores and conidiophores. 

 After King. 



