47° 



FUNGOUS DISEASES OF PLANTS 



Having gained entrance through the stubble or plant canes the 

 fungus invests the root system, and also the lower joints of the 

 stem, cementing the leaf sheaths together near the base with a 

 whitish mycelium. Not only is great injury done to the growing 

 stools, but a vastly greater loss results from missing hills of cane, 

 on account of the fact that the diseased stubble, or plant canes, 



may be so covered up by the 

 fungus that few stalks will be 

 produced. 



The fungus. Under favor- 

 able conditions (constant mois- 

 ture being indispensable), the 

 mycelium which is constantly 

 associated with the root dis- 

 ease may develop fruit bodies, 

 or sporophores. The type of 

 sporophore in the case of the 

 Louisiana disease is shown in 

 Fig. 233. It is described by 

 Fulton as follows : 



The pileus is dirty white, becom- 

 ing somewhat darker with age ; it is 

 usually about three fourths of an inch 

 in diameter, but may attain a size of 

 an inch and one fourth. When 

 young it is convex, and at maturity 

 is almost flat or perhaps slightly con- 

 cave. Its surface is smooth. On 

 the under side are the radiating gills 

 which have an even, thin edge, and 

 a straight, radial direction. The long 

 gills extend from the margin to the stem, and' are attached to the stalk itself 

 rather than to a prominent ring about the stalk. Other shorter gills extend 

 from the margin just far enough to fill in the angles between the longer gills. 

 The stipe is about equal in length to the diameter of the cap, or in some cases 

 somewhat less. It usually arises from the side of the leaf sheath, and is some- 

 what curved so as to bring the cap into a horizontal position. It is normally 

 attached to the cap at its central point, but at times this attachment is some- 

 what eccentric. The stipe is smooth externally, except at the base, which is 

 downy and also enlarged. The whole fruit cap persists for about a day, and then 

 gradually dries, losing its form, but not undergoing immediate disintegration. 



Fig. 233. Marasmius plicatus on 



Sugar Cane. (Photograph by 



H. R. Fulton) 



