148 



THE FUNGI WHICH CAUSE PLANT DISEASE 



Fig. 104. — P. trifolii. Ascus and paraph- 

 yses; germinating spores. After Ches- 

 ter. 



spores hyaline, 10-14 fi long; paraphyses numerous, filiform. A 

 Phyllosticta thought to be its conidial stage has been reported.*' 

 On dead spots in leaves of alfalfa and black medick. 

 P. trifolii (Bernh.) Fcl. 



This is closely related to, perhaps identical with, the last species. 

 Sporonema (Sphaeronaema) phacidioides Desm. is supposed to be 



its conidial form. This co- 

 nidial stage has not however, 

 been observed on alfalfa. 



Ascocarps mostly epiphyl- 

 lous, on dead spots, averaging 

 0.5 mm. broad, yellowish or 

 brownish; spores elliptic 10- 

 14 X 5-6 IX. 

 Conidia in cup-shaped pyc- 

 nidia which are numerous, small, light brown; disk cinnamon- 

 colored; conidia ovoid-oblong, 5 |i, bi-guttulate. 



P. tracheiphila Miiller-Thurgau ^^ is found upon the grape in 

 Europe. 



P. salicis (Tul.) Pot. occurs on Salix. Conidia ( =Glceosporium 

 saUcis). 

 P. ribis, Kleb."-" 



Apothecia appear in the spring on dead leaves of the previous 

 season; saucer-shaped, fleshy, somewhat 

 stalked; asci clavate, spores hyaline, 

 ovoid; paraphyses simple or branched, 

 slightly clavate, rarely septate. 



Conidial phase (=Glceosporium ribis) 

 on the leaves of the host forming an 

 abundant amphigenous infection; acer- 

 vuli stromatic ; conidiospores commonly 

 19 X 7 M, varying from 12-24 x 5-9 /i, 

 escaping in gelatinous masses. 



On red and white currants less com- 

 monly on black currants and gooseberries both in Europe and 

 America. 



The ascigerous stage of this fungus was demonstrated by 

 Klebahn " in 1906 to be genetically connected with what had been 



Fig. 106.— p. ribis. Apothe- 

 civuu in section. After Kle- 

 bahn. 



