240 SCIENCE AND FRUIT GROWING 



leaf often follows the severe pruning of plum trees, when the 

 wounds have not been treated in this way. It is to be feared, 

 however, that no such precautions can ever be quite effectual 

 in destroying weak spots where the fungus may enter ; luckily, 

 entry by the leaves appears not to be possible, otherwise, owing 

 to damage by aphis, there would always be an open door for the 

 fungus. The sterilisation of the pruning tools has already been 

 mentioned as advisable. 



