358 DISEASES OF CULTIVATED PLANTS 



The sporophores usually grow in dense clusters, and sur- 

 rounding objects become powdered with the falling spores, 

 presenting the appearance of having been dredged with flour. 

 Pileus 2-5 in. across, convex, then expanded, more or less 

 olive-brown when young, changing to dingy yellow or honey 

 colour when fully developed, and ornamented with minute 

 darker scales ; gills attached to the stem, dingy white ; stem, 

 3-5 in. long, coloured like the pileus, more or less ragged 

 below the large ring situated near its apex; spores white, 

 elliptical, 9 X 5-6 p. 



The fungus is edible and quite safe, but does not rank 

 amongst the best of edible British fungi. 



Where only comparatively few fruit or ornamental trees 

 are attacked, Hartig's suggestion of isolating such trees by 

 digging a narrow trench about a foot deep round each tree, 

 prevents the underground rhizomorphs from spreading to 

 neighbouring trees. This would be effective only if carried 

 out during an early stage of the disease, before the rhizo- 

 morphs had spread far in the ground. Where open trenches 

 are objectionable, tarred boards or sheets of galvanised iron 

 could be sunk in the ground to a depth of six or eight 

 inches. All sporophores of the fungus should be collected 

 and destroyed before their spores are dispersed. The above 

 methods are almost impracticable when dealing with extensive 

 woods, etc. 



Hartig, Die Zersekzung. des Holzes, p. 59. 

 Hartig and Somerville, The Diseases of Trees (Engl. ed.), 

 p. 207. 



Prillieux, Malad. des Plantes Agric., i, p. 377. 



MARASMIUS (FRIES.) 



Tough, thin, dry, reviving when moistened, and not putre- 

 scent ; stem cartilaginous or horny ; gills tough, distant, often 

 connected by veins, spores white. 



Banana plant disease. This disease is very prevalent in 

 some of the West Indian islands, and is caused by a small 

 agaric called Marasniius semiustus (Berk, and Curt.). It 

 often occurs in immense numbers on the stem of the banana 

 plant, and the mycelium infects the flower-stalk and the 

 inflorescence as they grow up the centre of the leaf-sheaths 

 forming the spurious stem. Numerous minute, whitish 



