Fungus Disease oe Fruit Trees. 



361 



A Fungus Disease of Young Fruit Trees. 

 Eutypella prunastri (Sacc). 



Every now and again this minute but very destructive para- 

 site appears under the form of a disease wave, causing a very 

 considerable amount of damage, hundreds, or in some instances 

 thousands, of young trees being injured or completely killed 

 during one of these sporadic attacks. 



Young standard fruit trees, up to the age of eight years, are 

 most liable to the disease, and as the stem or stock is the part 

 attacked, the girdling of this portion of the plant by the fungus 

 growing in the bark and cambium means the death of the entire 

 tree, which in a dull and damp season favourable to the rapid 

 growth of the parasite, usually occurs during the spring follow- 

 ing the first year of attack. 



In the case of nursery stock, plum (especially the variety 

 called Victoria) and apple trees have suffered most severely 

 in this country ; peach, apricot and cherry to a less extent. 

 The fungus is also often very abundant on wild plum, bullace, 

 blackthorn, &c, and it is the spores produced on such wild trees 

 that infect cultivated stock. 



The first indication of the presence of the disease is the 

 premature yellowing and fall of the leaves, followed by a drying 

 up, browning, and shrivelling of the bark of the stem. During 

 the spring following the first year's inoculation, numerous 

 minute, elongated cracks, arranged in dense clusters, appear in 

 the dried-up bark. These represent the first form of fruit pro- 

 duced by the fungus (Fig. 1), and are followed during the second 

 season after infection by larger, fewer, and more irregularly 

 scattered cracks, always transversely arranged in the now dead 

 bark, containing a second and more highly developed kind of 

 fungus fruit (Fig. 3). 



The spores of the fungus are mature during late spring and 

 early summer, and it is at this season that infection of young- 

 fruit trees takes place, the spores gaining access to the stem 

 either through the unprotected ends of pruned twigs or through 

 the living bark itself. 



All wounds on the stem exposed by cutting off shoots, Jiozv- 



