314 



PLANT DISEASES 



which when magnified is seen to consist of pale olive 

 upright conidiophores, each bearing at its apex or tip a 

 large spindle-shaped, many-septate, pale olive conidium. 



In some cases the blotches become much elongated, and 

 do not run into each other. The mycelium spreads in the 



Fig. 84. Helminthosporium turdcum. i, portion 

 of an Indian corn leaf, diseased ; 2, a tuft of conidio- 

 phores bearing two conidia, x 300. 



tissue, which finally becomes dry and brittle. The appear- 

 ance of the fruiting condition on the surface of the leaf 

 depends much on climatic conditions; if uninterruptedly 

 warm and moist, the leaves often become brittle, and fall 

 to the ground in fragments before the conidia are formed ; 

 these however do develop on the pieces lying on the ground. 



