154 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



appear, and tinally the wood becomes a moist mass of crumbling 

 shreds of a light yellowish-bi'own colour. 



The spread of this disease is eflfected underground; hence 

 cutting the tree off above ground is of no use — it must be 

 removed, root and all. This is quite practicable in young planta- 

 tions, and should be done directly the tree shows symptoms of 

 the disease. In old woods this operation is not so easily accom- 

 plished, but much gooi may be done by isolating the diseased 

 area by means of a circular ditch, over which no roots should be 

 allowed to pass. The ditch must, of course, be sufficiently large 

 to entirely include the infected area. The sporaphores should, as 

 far as possible, be collected and burned. 



Agaricus melleus. — This fungus has been sent in from several 

 different sources. It is very common in coniferous woods. It may 

 attack trees up to a hundred years old. Young trees which have 

 been killed by it usually have a hardened mass of earth adhering 

 to their roots. The earth is bound together by the resin which 

 exudes copiously from the diseased specimen. If the bark is 

 removed from the roots or stool, the tough white mycelium of the 

 fungus is seen. From this mycelium the well-known caps are 

 formed in autumn. 



Sphcerella Taxi. — This disease was first described by Dr M. C. 

 Cooke in 1878. At that time it was observed to be spreading 

 from Cornwall through Devonshire to Somersetshire and Dorset- 

 shire, but was not known to have spread farther. 



In 1884, Dr W. G. Smith further investigated this fungus, 

 which he describes as follows: — "The leaves of the attacked yew 

 show numerous minute black dots ; these are little spherical 

 cavities (Sphcerellce) surrounded by a dark cellular investment, 

 and sunk in the tissue of the leaf. In these cavities the asci are 

 produced. These are sausage-shaped sacs, each containing eight 

 spores, which escape a': maturity in large numbers. Owing to 

 the hard, firm epidermis of the yew leaves, the germ threads of 

 the spores cannot enter except by the stomata." This, Dr W. G. 

 Smith points out, is no doubt the reason why the fungus is pro- 

 gressing so slowly towards the midlands and the north. The 

 diseased leaves fall to the ground, and there the spores are pre- 

 served in a suitable moist and sheltered position The remedy 

 c insists in cutting off and burning attacked branches or branchlets 

 as soon as they show the symptoms of disease. 



Coccus Fagi. — This insect forms a white woolly covering on the 



