4. PLANT DISEASES DUE TO FUNGI. 



STEM DISEASE OF FRUIT TREES. 



Eutypella prunastri (Sacc.). 



Throughout the Midland counties young apple, pear, and plum 

 trees have suffered severely from this disease, which appears to be more 

 prevalent now than I have ever known it before. 



In addition to the above trees, almonds, apricots, blackthorn, 

 bullace, cherries, peaches, and wild plums are liable to be attacked. 

 The " Victoria " plum is said to be the most susceptible to infection 

 with this fungus. 



The first indication of the disease is the occurrence on the stem 

 and branches of small shrunken patches of bark which have a dry and 

 dead appearance. Later these continue to increase in size until they 

 extend completely around the stem. Over the whole of these areas 

 a series of minute bodies appear the openings of the receptacles 

 that contain the fruit bodies. 



The mycelium of the fungus, in the meantime, has made its way 

 into the tissues of the plant, stopping up the vessels and so preventing 

 the passage of the water from the roots. The source of food supply 

 to the leaves having been cut off, or almost so, the leaves die and the 

 tree commences to do so also. Sometimes a few leaves are produced 

 the following season, but these quickly turn yellow, wilt and fall off. 



If the dead tree is allowed to remain, a series of larger pustule- 

 like bodies appear, containing the second or ascigerous form of fruit. 



Mr. George Massee, in his excellent text-book, 1 states " In all the 

 cases I have investigated in the field, the common practice of planting 

 too deep had been followed, and this I feel assured has something to 

 do with the disease, more especially when the soil is inclined to be 

 stiff. Under such circumstances numerous large lenticels are formed 

 on the stem, and I have found by experiment that if the spores of 

 the conidial condition of the fungus are applied to such lenticels during 

 damp weather infection follows." My own experience corroborates 



1 Diseases of Cultivated Plants, 1910, p. 172. 



