66 RATIONAL FRUIT CULTURE 



chaptj:r XI. 



FUNGOID DISEASES OF FRl IT TREES. 



IF the common fungoid diseases of fruit trees are not as 

 numerous as the injurious insects, they are often more 

 persistent, and may be even more serious in their effects. 

 Iiike the insects, they attack different parts of the tree — the 

 foliage, the branches, or the fruit; sometimes more parts than 

 one. As a rule, they may be regarded as a sign of something 

 wrong with the cultural methods, for the first trees to suffer 

 are those that have been weakened by want of food, defective 

 drainage, scarcity of fresh air, or some similar cause. It is 

 essential, therefore, to ascertain what is wrong, and to en- 

 deavour to remedy it. Unless that is done, no kind of special 

 treatment is likely to be permanently successful. 



BOW INFECTION TAKES PLACE. 



Fungoid disease is introduced into a healthy orchard by 

 means of spores. They may be brought from an infected area 

 by the wind, by birds, or flying insects; even by dirty tools, 

 or on the boots. When the conditions of temperature and 

 moisture are favourable, the spores germinate, and if the en- 

 vironment is suitable for their development — if, for instance. 

 thase that attack the leaves of a particular species are on such 

 leaves — they penetrate the tissues, and the fine thread-like 

 mycelium grows rapidly inside them. 



MMITATIONS TO INFECTION. 



Fortunately, each species of parasitic fungus has its own 

 particular host-plant, on which its life is spent. It may some- 



