IS'ew York Agiucultural Expeiriment Station. 127 



now DISTINGUISHED FROM OTHER CURRANT LEAF 



DISEASES. 



Among fruit growers the currant disease under consideration 

 is usually known as leaf blight or sometimes as leaf spot. Since 

 there are at least two other common currant leaf diseases which 

 go by the same name much confusion would be avoided if fruit 

 growers would follow the custom of mycologists and call this 

 disease anthracnose. Mycologists apply the name anthracnose 

 to diseases caused by species of fungi belonging to Glccosporium, 

 Gollototnclmm and a few other closely related genera. 



The currant disease which is properly called leaf spot is the 

 one caused by the fungus Septoria rihis Desm. This produces 

 on the leaves dead, brow^n (or gray) spots which are usually 

 circular in outline and have a dimeter of about one-eighth inch 

 (See Plate I, Fig. 8). As a rule, leaf spot is readily distinguished 

 from anthracnose by the size of the spots, anthracnose spots 

 being much smaller — often no larger than a pin head. However, 

 the spots formed by Septoria ribis on both red and black cur- 

 rants, may sometimes be angular and quite small, although 

 always larger than those of Glccosporium rihis. A notable exam- 

 ple of this came under our observation at Milton where a large 

 plantation of black currants, liibes nigrum, was quite severely 

 attacked by leaf spot as early as July 10, Since, at this date, 

 Septoria rihis had showm itself only in traces on red currants in 

 this locality, and the character of the spots was so much out of 

 the ordinary, we were much surprised to find that the trouble 

 was due to Septoria rihis. The spots were quite angular and 

 scarcely more than one-third their usual size. The variety of 

 currant is one said to have originated near Milton where it is 

 known as the Mackey. 



The Septoria leaf spot is very common in New York and is 

 usually the chief cause of the dropping of currant leaves in this 

 State; but during the past season it was almost wholly absent 

 from the locality where anthracnose was epidemic until about 



