436 PROTECTION AGAINST FUNGI. 



presence of this parasite is decidedly shown by the appearance 

 of black spots surrounded by white colour in the spring-wood. 

 Outwardly the mycelium penetrates cracks in the bark, in the 

 form of small yellowish -white tufts. 



The sporocarps are chiefly on the root-stalk, but also on 

 the roots, either in the form of incrustations or masses like 

 yellow or snow-white grapes. Under favourable circumstances 

 of growth they may assume the form of brackets. 



The disease generally spreads rapidly, turning the wood 

 first brown and then white and causing large hollows in it. 

 By the artificial infection of six ten-year-old Scots pines, five 

 of them were killed in a year and a half. (K. Hrtg.) .* 



b. /Subjects of Attack. 



The fungus has been observed on the Scots and Weymouth 

 pines, the spruce, silver-fir, of all ages up to 90 years, also on 

 juniper and on Scots pine transplants from five years old. 

 Pinus rigida, Mill., is very susceptible to its attacks. Its 

 spread is favoured by mice and other animals which carry 

 the spores in their fur. Trees which are attacked have pale 

 needles and stunted shoots, as in the case of the honey fungus. 



c. Protective Rules. 



i. Mixing broadleaved trees with conifers. 



ii. Kemoval of all infected trees and of all rhizomorphs, as 

 soon as they are noticed, and filling up the gaps with broad- 

 leaved species. 



iii. Digging up and charring all roots which show traces of 

 sporocarps. Hess considers isolation-trenches of little use in 

 this case, as they only favour the production of conidia from 

 the exposed hyphae. Hartig, however, considers it possible to 

 scrape the walls of the trenches free from conidia, though this 

 could probably be done only in isolated cases of the disease. 

 Isolation trenches will at any rate prevent the infection of 



* Mr. B.T. Butler, cryptogamic botanist to the Government of India, wrote a 

 paper (" Indian Forester," Nov. 1903) showing that F. annosus, Fries., has black 

 rhizomorphs. Such were also discovered by Dr. Mayr. Professor of Forestry, 

 Munich. They penetrate the soil to a depth of 20-30 cm., one descending 3 m. 



