STATE HORTICULTURAL SOCIETY. 



219 



Figure 4— Leaf of currant showing diseased spots. 



A CURRANT DISEASE, 



In Western Massachusetts last summer (1885) the currant bushes 

 were badly injured by a fungus. (Septoria ribis, Desm.) growing on the 

 leaves. The same occurs in this region on wild currants and goose- 

 berries, on the cultivated currant in Ohio, and on gooseberries in Ken- 

 tucky. The disease appears as brown spots on the leaves, angular 

 spots limited by the veins and soon becoming dead and dry. The spots 

 are good sized and when large or numerous, destroy nearly the whole 

 leaf. It certainly has an exhausting effect on the leaf and many leaves 

 become entirely exhausted and fall off. 



The microscope shows the presence of a fungus growing among the 

 leaf tissues in the usual way, but its mode of fruiting is quite different 

 from those described before. Within the tissues and somewhat pro- 

 truding on the surface are minute blackish postules or spore-cases 

 (perithecia). At the base of the perithecia, within, arise threads 

 which bear the spores. The spores are colorless, very slender and 

 thread-like, curved, pointed at the free end. 



The life history of this fungus is unknown, but 

 it is known that many of this group are only 

 Figure 5— Spore of currant the Summer stages of spccies which live through 



disease, lilghly magnified. ,-, . . ■, , • i , • i 



the winter and mature in late winter or spring, 

 either on the same spot with the summer form, as in the black knot 

 of the plum trees, or on different parts where the summer spores have 



