CURRANT DISEASES 205 



the young leaves. The ascospores germinate and their germ- 

 tubes enter the leaves, wherein mycelium is developed. In a 

 short time the leaf-tissue is killed in local areas and the result 

 is a spot. Finally asexual, summer, fruiting bodies are formed. 

 These are black, spherical structures, called pycnidia, occupy- 

 ing the central portion of the lesion. At maturity each pycnid- 

 ium is filled with long, curved pycnospores. These ooze out 

 and are scattered promiscuously. Some perchance fall on 

 currant or gooseberry leaves ; they germinate and cause spots. 

 Some time during the summer (June to August) the affected 

 leaves fall, and preparations for the winter are again made by 

 the fungus. Damp cloudy weather favors the fullest develop- 

 ment of Mycosphcerella Grossularice. 



Control. 



The spraying schedule for currant-anthracnose is reliable 

 for the control, of this leaf-spot. Five to seven applications 

 of lime-sulfur used at the rate of one gallon of lime-sulfur solu- 

 tion (commercial concentrate) to fifty gallons -of water are 

 effective. Finely ground sulfur (dust), ninety parts, and 

 powdered lead arsenate, ten parts, has been shown to be satis- 

 factory. The spray or dust should be applied : (1) when the 

 first leaf-clusters appear; (2) subsequently every two weeks 

 until the first of August. (See Control of Currant Anthrac- 

 nose, page 208.) 



REFERENCES 



Stewart, V. B. Dusting nursery stock for the control of leaf diseases. 



Experiment for the control of the leaf spots of currants. Cornell 



Univ. Agr. Exp. Sta. Circ. 32 : 8-9. 1916. 

 Stewart, V. B. Some important leaf diseases of nursery stock. Sep- 



toria leaf-spot of currants and gooseberries. Cornell Univ. Agr. 



Exp. Sta. Bui. 358 : 198-200. 1915. 

 Pammel, L. H. Spot diseases of currants and gooseberries. Iowa 



Agr. Exp. Sta. Bui. 13 : 87-70. 1891. 

 Pammel, L. H. Treatment of currants and cherries to prevent spot 



diseases. Experiments with currant spot diseases. Iowa Agr. 



Exp. Sta. Bui. 30 : 289-291. 1895. 



