SEEDLING OAK DISEASE 121 



cial in France is to expose the base of the trunk as far 

 down as can be done without injury to the tree, and to 

 powder both trunk and surrounding soil liberally with 

 powdered sulphur, repeating the process at intervals. 



Hartig, Unters. aus dem Forstbot. Inst. zu Milnchen, vol. 

 iii. pp. 95-141. 



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

 p. 82, figs. 



Viala, Monog. du Pourridie des Vignes et des Arbres 

 fruit iers, 5 pi. 



SEEDLING OAK DISEASE 

 (Rosellinia querdna^ Hartig.) 



Hartig has described a disease which is common in 

 Germany, attacking the roots of seedling oaks. It presents 

 several features in common with the parasite called Dema- 

 tophora necatrix^ which, judging from the mature ascigerous 

 fruit, as described by Viala, is also a species of Rosellinia. 



The disease is most prevalent during wet seasons. 

 Affected plants are indicated by withering of the leaves, 

 and on being removed from the ground a white thread- 

 like mycelium, along with minute black sclerotia, are 

 found. These mycelial strands, which eventually become 

 brown, traverse the soil and attack the roots of neighbour- 

 ing plants. 



^Perithecia, producing ascospores, are also formed on 



dying roots. Conidia are also formed on branches of 

 the mycelium running on the ground. 



PREVENTIVE MEANS. Diseased patches should be iso- 

 lated by a trench, to prevent the spread of the mycelium. 



