234 DISEASES OF CULTIVATED PLANTS 



has been killed by the fungus is examined, its surface is found 

 to be more or less covered with fine thread-like strands of white 

 mycelium. When the root is in the ground, these strands of 

 mycelium spread on the surface of the ground during damp 

 weather, and change to a brown colour. Numerous minute 

 blackish sclerotia are also formed on the surface of the dead 

 root. These strands of mycelium traversing the ground 

 penetrate very readily the tissues of young rootlets not yet 

 protected by a layer of periderm, and enter all the tissues, 

 and in less than fifteen days a root thus attacked has all its 

 wood completely destroyed, a hollow tube formed by the 

 bark alone remaining. During this process of destruction 

 compact masses of mycelium resembling flattened sclerotia 

 are formed in the bark. At a later stage these sclerotia give 

 origin to strands of mycelium which radiate in every direction 

 in the soil. Conidial fructification is produced on the 

 mycelium surrounding the collar of the stem and adjoining 

 soil. The conidiophores are slender, hyaline, erect, and 

 bear two or three whorls of short branchlets near the apex. 

 Each branchlet bears at its apex a minute, shortly cylindrical, 

 hyaline conidium. At a later date the ascigerous form of 

 fruit is produced on a dense weft of mycelium covering the 

 base of the stem and superficial roots, and on strands of 

 mycelium on the ground. 



Ascigerous form. Perithecia scattered or subgregarious, 

 seated on blackish mycelium, black, globose with a minute 

 papilla or mouth, about i mm. diam. ; asci subcylindrical, 

 8-spored, 160-170x8-10 /i; spores obliquely 1 -seriate at first, 

 fusoid, guttulate, both ends rather acute, brown, 28x6-7 \i. 



The disease appe. us to be confined to young trees in the 

 nursery ground. When it appears at a given point it rapidly 

 spreads by means of its underground strands of mycelium. 



Seedlings that are attacked should be removed, and an 

 open trench made at some distance from the centre of 

 disease, to check its extension. The fungus is very impatient 

 of moisture ; plenty of air and good drainage are essential. 



Hartig, Unters. aus d. Forstbot. zu Miinchen, 1SS0. 

 Hartig and Somerville, Diseases of Trees (Engl. ed.K 

 p. 78(1894). 



Mulberry root rot (Rosellinia agui/a, De Not.) is 

 frequently the cause of serious injury to the mulberry-tree, 

 which as a rule results in the death of the tree attacked. 



