212 AGRICULTURAL EXPERIMENT STATION. [Jan. 



II. A violet disease. 



III. The black knot of plum and cbei'ry. 



IV. Grain rusts. 



A'. Various diseases. 



1 . Powdery mildew of strawberry. 

 '1. Powdery mildew of gooseberry. 



3. Cluster cup of gooseberry. 



4. A hazel fungus. 



VI. Treatment for powdery mildews. 



As before, the " General Account of the Fungi," on pages 

 195 to 211 of the seventh report of this station, may l)e 

 found useful as an aid to the full understanding of the follow- 

 ing discussions. 



I. Diseases of the Cucumbeu Plant. 



1. A ScLEROTiuM Disease. — Sclerotinia Libertiana F'k'l (Plates 



I. and 11.) 



A subject concerning which many and urgent inquiries 

 have been addressed to the writer by growers of winter 

 cucumbers near Boston is the disease known amono- them as 

 " timber rot." * This trouble makes its appearance regularly 

 in the spring, when the plants are well grown and m bearing, 

 and is a cause of much loss. The first specimens showmg 

 the nature and effects of the disease were received in May 

 last, from W. W. Rawson, Esq., of Arlinglon ; and subse- 

 quently a visit was made to his greenhouses, where the dis- 

 ease was seen in various stages of development, and further 

 specimens for study were obtained. 



The most cursory examination of good specimens makes 

 it evident that we have here to do with a fungous disease 

 of much interest. It attacks chiefly the stems of the host- 

 plants, sometimes the fruits. I am not aware that it ever 

 attacks this crop out of doors, l)ut in the warm and moist 

 atmosphere of the cucumber house the fungus finds very 



* Concerning the origin of this name it is not easy to suggest an explanation. 

 Popular names of diseases serious enough to attract attention are usually in some 

 way descriptive or otherwise appropriate. The present name has little of such 

 quality to recommend it, and I have no clue to its origin, unless the appearance of 

 the fresh mycelial threads on the stem may have suggested that of the mycelium of 

 MeruUua lachrymans and other hymenomycetous species which attack wood. 



