POCKET-PLUMS,' OR 'BLADDER-PLUMS' 85 



tissues ; and soon after growth of the leaf recommences, 

 the fungus manifests its presence by causing curling and 

 discoloration of the tissues. On the other hand, when 

 evidence of the activity of the fungus has been unmis- 

 takable, its further course has been completely checked 

 by a sudden increase of temperature. The disease was 

 very abundant in the south of England during the season 

 following the exceptionally cold winter of 1894-95. 



Spraying with dilute Bordeaux mixture just when the 

 leaf-buds are beginning to expand, and again after an 

 interval of three weeks, would be beneficial as a safeguard 

 against inoculation from wind-borne spores. 



Rathay, Osterr. Bot. Ztg., 1880, No. 7 ; and in LXXXIII. 

 Bande der Sitzb. d. K. Akad, d. Wissensch., I. Abthl. 1881. 



1 POCKET-PLUMS,' or 'BLADDER-PLUMS' 

 (Exoascus pruni, Fckl.) 



The widespread disease of plum-trees, known in different 

 districts by one or other of the above names, is caused by 

 a minute parasitic fungus, the mycelium of which is 

 perennial in the host-plant, living in the tissues of the 

 young branches, and extending into each new growth of 

 the host that is formed beyond the point at which the 

 branch was first infected by the parasite. In this instance 

 the fruit alone is modified and destroyed by the fungus, 

 whereas in allied species the leaf is the part which serves 

 for enabling the fungus to develop its fruit, and expose its 

 spores on the outside of the host, so that they may be 

 readily dispersed by wind and other agents when mature. 



