92 FRUIT TREES AND THEIR ENEMIES 



other stone fruit besides plums, as well as Portugal 

 laurels, laburnums, and, more rarely, apples. It is 

 recognised by the silvery appearance of the leaves, 

 which, however, is not due to the presence of the 

 fungus itself, but is the result of changes produced in 

 the leaf-cells by its action : the fungus only fruits on 

 the dead wood, after it has killed the tree, forming 

 thin purplish disks, often two inches or more in 

 diameter. Infection seems generally to be spread by 

 the spores of the fungus entering through a wound in 

 the tree. 



Remedies, — No remedies are known, but certain 

 preventive measures may be taken. All large 

 wounds should be tarred over, and in any plantation 

 where the disease exists, the ends of pruned branches 

 should also be tarred. If only one or two branches 

 of a tree are affected, they may be removed, with some 

 chance of stopping the infection ; if the whole tree is 

 affected, it should be cut down and burnt. This is 

 specially necessary when any of the fruiting fungus is 

 found on the trees. The tools used in the operation 

 should be disinfected by washing with carbolic acid or 

 paraffin. Soft-wooded varieties, especially Victorias, 

 are most liable to infection ; and high feeding, which 

 results in rapid and soft growth, favours an attack. 

 Trees which are not badly affected will sometimes 

 recover without any removal of branches. 



Wasps. — The damage done to plums and other 

 fruit by wasps needs no description. 



Remedies. — The well-known method of trapping 

 them in bottles half full of sour beer and sugar is one 



