64 



rUXGI AND PUKGICIDES 



disease. Various names of fungi have been used in 

 connection with it^ one of the commonest being Septoria 

 cerasina. The name printed above is the one now 

 accepted by botanists. 



Tlie leaf-blight is especially destructive in the nur- 

 sery, the young trees often 

 being defoliated before the 

 middle of August. Bear- 

 ing plum trees also lose 

 their leaves prematurely 

 on account of it. 



Treatment. — Exper- 

 iments conducted on an 

 extensive scale by the Ohio 

 Experiment Station show 

 that in the orchard this j 

 disease may be prevented ' 

 by spraying with dilute 

 Bordeaux mixture. Two 

 or three sprayings early in 

 the season are deemed sufH- 

 cient. It should not be 

 used too late, on account 

 of the liability of the mix- 

 ture to remain on the 

 ripened fruit. In the nur- 

 sery the Bordeaux mixture 

 is also a preventive ; the 

 results of its use are well 

 represented in Fig. 34, re- 

 duced from photographic 

 views of experiments conducted by the Division of 

 Vegetable Pathology. 



Literature. — This disease has frequently been dis- 

 cussed in our horticultural literature, although very 

 little of value concerning remedies has been published 



FIG. 33. DISEASED PLUM LEAF. 



