CORAL- SPOT DISEASE. 479 



common in the British Isles, especially on apple trees. It is 

 frequently associated with the attacks of the insects mentioned 

 above, which expose the cambium zone to the admission of 

 spores, by the wounds they make in the bark. 



c. Protective Rules. 



Cut out all infected trees in cleanings and thinnings, pro- 

 vided too large gaps are not thus caused in the standing-crop. 



Avoid all injuries to the bark during felling operations. 



Afi'ected branches in orchards should be pruned down to 

 the sound wood (October till' March), and the exposed sections 

 covered with coal-tar. 



Burn all cankered wood. 



4. Nectria cinnaharina, Fr. 



(Coral-spot Disease.) 



a. Description and mode of Attack. 



The presence of this parasite in living broadleaved trees 

 may be diagnosed by the breaking out of the vermilion- 

 coloured sporocarps, which eventually turn brown and finally 

 white, on the stem or branches of the tree, chiefly in the 

 autumn, after rainy.weather. Healthy shoots suddenly dry 

 up and die, the wood turning green or black. The infection 

 takes place at a wound of some kind, chiefly of branches, but 

 also of. roots. The mycelium grows rapidly in the wood, 

 pierces the walls of the wood-fibres, decomposes the starch, 

 and leaves a green substance within the infected tissues. The 

 cambium and bark remain sound, but by the destruction of 

 the wood, the water-supply is cut off from the crown, tli'e 

 leaves witlier and drop off, and the shoots dry up. The sporo- 

 carps appear in autumn or spring on the dead l)ark of the 

 infected trees, and the danger of infection is then greatest. 

 Severe frost or sun-blister may produce wounds," through 

 which the spores gain admission to the wood. 



b. Subjects of Attack, anil iJis/ritnituni. 



This fungus is saprophytic on the dead branches of various 

 broadleaved trees and shrubs, such as uiaples, cherries, robinia, 



