DETAILED ACCOUNT OF SPECIFIC DISEASES OF PLANTS 51I 



Fig. 183. — Details of cranberry scald fungus (Guignardia vaccinii). i, A cran- 

 berry leaf, showing pycnidia of Guignardia vaccinii thickly scattered over the under 

 surface; a, a cranberry blossom blasted by Guignardia vaccinii, showing pycnidia on 

 calyx, corolla, and pedicel; b, a blasted fruit, showing pycnidia. 2, A vertical section 

 of a single pycnidium of Guignardia vaccinii from a cranberry leaf, showing pycno- 

 spores in various stages of development. 3. An immature pycnospore of the same 

 fungus, showing the partially formed appendage; a, the same, showing a little later 

 stage of development; h and c, fully developed pycnospores and appendages. 4, 5, 

 6, 7, 8, and 9, Various stages in the germination and growth of pycnospores oiGuig- 

 nardia vaccinii grown in weak sugar solution; 4, 5, 6, and 7, 72 hours after sowing; 

 8 and 9, 86 hours after sowing. 10, A vertical section of a perithecium of Guignardia 

 vaccinii, showing asci, from a cranberry leaf collected in New Jersey. 11, Three 

 asci, with ascospores showing variations in length of the stipe and the arrangement 

 of the spores; a and b, from perithecia on a leaf; c, from a pure culture. 12, A fresh, 



