Galls caused by the Fungus Exoascus insititiae Kerner 



on 



the fruit of Prunus insititia Linn. 



PLATE 126. 



Synonymy of the Fungus. 



Exoascus Pruni De Bary, M. Ward, Connold. 



Habitat of the Bullace-tree.— It is found wild in woods 



and hedgerows in various parts of Britain, but in a 



cultivated condition it is in almost every orchard. 

 The Gall is formed by the attacks of the fungus, which 



absorbs the food substances from the Hving cells of the 



growing fruit. 

 Position.— Amongst the unaffected fruit. 

 Manner of Growth.— Singly, and in clusters of three to 



nine on one twig. 

 Colour.— At first pale green, later greyish, spotted with dingy 



yellow and orange. 

 Average Dimensions of a Mature Specimen. 



Length, 40 mm.; breadth, 15 mm.; girth, 40 mm. 

 May be sought during the months of June, July, and August. 

 The Growth is complete by the end of July. 



The popular names of the galled and swollen fruits are 

 " pocket-plums " and " bladder-plums." The fungus also 

 attacks other varieties of the Pruniis genus. When it has 

 established itself on a tree it is difficult to eradicate. Pickmg 

 off" the affected fruit and burning it as soon as it shovvs 

 symptoms of disease, should not be neglected. Deep prunmg is 

 also effectual. Some old trees require vigorous treatment m 

 this respect. See also plate 129. 



The gall is also figured by Marshall Ward, "Diseases of 

 , Plants," p. 108; Hastings Natural History Society's seventh 

 ' Annual Report, 1900. 



28S 



