210 MANUAL OF FRUIT DISEASES 



(Ribes vulgare). It is also found on the cultivated varieties of 

 the black currant (Ribes nigrum), and the European gooseberry 

 (Ribes Grossularia) . The Wilder currant is said to be very 

 resistant to cane-blight. 



The disease has been more or less under the careful observa- 

 tion of American pathologists during the past quarter of a 

 century. In 1899 it was studied in New York State under the 

 name of cane-blight. More recently (1911) it has again been 

 given detailed attention in New York. It occurs in Delaware 

 and probably elsewhere, although its confusion with another 

 trouble has made the determination of its range difficult. The 

 history of cane-blight shows that it may become epiphytotic 

 in regions where it is established. 



Symptoms. 



The conspicuous symptoms of cane-blight consist of a sud- 

 den wilting and dying of parts or of whole bushes here and 

 there throughout a plantation. This occurs during the sum- 

 mer, at any time while the plants are in leaf. The leaves 

 wilt, turn brown, and die on certain canes or portions of canes. 

 Finally the leaves fall. The affected wood of a cane is killed 

 at a point some distance below the wilted foliage. 



Cause. 



Currant cane-blight is due to the work of a fungus, Botryo- 

 sphoeria Ribis. It attacks the canes, and the symptoms just 

 described result. It was formerly thought that the disease 

 was due to Nectria cinnabarina. The fungus B. Ribis passes 

 the winter in the young blighted or dead shoots, or in small 

 cankers. With the advent of the growing-season the pathogene 

 invades and blights the parts below. The spores of the fungus, 

 which develop on the affected parts, may be carried to other 

 plants by the wind or the American currant-borer. It is sug- 

 gested that the beetle's habit of oviposition may have some 

 relation to the dissemination of the fungus. The currant is 

 most easily infected, that is, most susceptible, during its period 



