GUIGNARDIA 167 



is furnished with an opening at the apex through which the 

 spores escape. This opening or mouth may be a minute hole 

 at the apex of the perithecium, or it may be prolonged into a 

 beak of variable length in different species. The perithecia 

 are always minute, and may be scattered singly on the host, 

 or aggregated in immense numbers on a stroma, or compact 

 mass of fungus hyphae of variable form. The spores are 

 produced in asci contained in the perithecium. Conidial 

 stages are abundant in this group, and present great variety 

 of form and structure. 



There is no recent work in English on the classification of 

 the Pyrenomycetes. 



Saccardo, A. P., Sylloge Futigorum, etc., 1 and 2. 



A. Spores continuous ( = 1 celled), hyaline {sometimes 

 tinged yellow). 



GUIGNARDIA (Viala and Ravaz) 



Perithecia innate, lenticular, usually with a projecting 

 mouth, membranaceous ; asci 8-spored ; spores elongated, 

 continuous, hyaline ; paraphyses absent. 



Black rot of grapes. Undoubtedly the most destructive 

 fungus parasite with which American viticulturists have to 

 cope. Ever since its introduction into Europe in 1885 along 

 with vines brought from the United States to replace those 

 destroyed by the Phylloxera, it has proved very destruc- 

 tive, more especially in the case of vines growing in the open 

 air. Both conidial and ascigerous forms of reproduction are 

 known, and the characteristics of the disease are so well 

 marked, that it cannot be mistaken for any other form of 

 disease affecting the vine. Guignardia Bidwellii (Viala and 

 Ravaz) is the name of the fungus causing all this injury and 

 loss. On the leaves the fungus causes irregularly circular, 

 small, sharply defined, dead spots, these sometimes encroach 

 on each other and form irregularly shaped patches, which in 

 course of time become more or less covered with minute 

 black perithecia, often arranged in concentric lines, on both 

 surfaces of the diseased spot. This condition of the fungus 

 was at one time called Phoma uvicola (Berk, and Curt.). Near 

 the succulent green tips of the shoots the spots are usually 



