THE FUNGUS CAUSING BLAST AX!) ^^CAI.D. If) 



exposed. In most cases Ihcy ;iic lliickly aiul evfiily distribiiled oxer 

 tlie surt'aec of the leaf, except for the iiifi-e(iueiit occasions when only 

 a portion of the h'af has been killed l)y the fnni2.iis (IM. II, ii<>s. 1 and 

 2). Matnre pycnidia contain <rreat numbers of i)ycn()spt)res, bearing; 

 at their apexes a rather inconspicuous appendage consist inn; • of 

 granular matter, which appears to be embediled in a somewhat gelat- 

 inous substance. They are borne on short, sinipk> sporophores 10-1.") fj. 

 long. These pycnospores are hyaline, obovoid, with the ajK'X fre- 

 quently truncate, and measure from 10..") to i-\St by 5 to (> j-i. The 

 apjxMidage is usually about the length of the spore, or somewhat less, 

 and cui-ved (PI. II, fig. -^, a, h, c). At maturity these pj^cnospores 

 are expelled from the jjycnidium in a small gelatinous tendril or 

 threadlike mass, being held together by the gelatinous substance of 

 the spore appendages as Avell as the free gelatinous matter which 

 appears to be i)roduced within the pycnidium and forms a thin layer 

 about the pycnospore. 



Ascoc/evoiis form. — The ascogenous perithecia are much less fre- 

 quently found than the i)ycnidia. The perithecia resemble the pyc- 

 nidia very closely in form, size, and other characteristics (PI. II, 

 fig. 10). In fact it is almost or (piite impossible to determine, in the 

 absence of asci or p3^cnospores, to which form a i)articular fi-uiting 

 body may belong. The perithecia seem to have a denser, somewhat 

 more opaque wall than the pycnidia, and they contain oblong, or 

 somewhat clavate, short-stipitate, or sessile asci, the spore-bearing 

 portion varying from 52 to 60 by 9 to 12 /x, the total length being (JO 

 to 80 /A (PI. II, fig. 11). The asci contain eight hyaline, or, when 

 old, slightly yellowish brown, short elliptical or snbrhomboid asco- 

 spores, having the contents rather coarsely granular (PI. II, fig. 12). 

 They vary in size from 13 to 16.5 by G to 7 ju,. No paraphrases have 

 been found. The characters of the ascogettious form of this fungus 

 seem to agree most nearh^ with Ihose of the genus Guignardia and 

 correspond ver}^ closely to the black-rot fungus of the grape {Guig- 

 nardia huhvellii (Ell.) V. & R.). The pycnidial stage of G>ik/nnrdia 

 hidireJJii, as described and illustrated by Viala ^"^ and others, differs 

 from the ])ycnidial stage of the cranberry scald fungus in scarcely 

 any particular except in the absence of the spore appendage. A 

 recent careful study of fresh pycnidia of Guignardia hidwellii show^s 

 that its pycnospores also bear a similar appendage. It is, however, 

 shorter and less easily distinguished than that of Guignardia vaceinii, 

 and soon disappears in mounted specimens. The appendage in the 

 case of the cranberry fungus is very constant and characteristic. 



The cranberry scald fungus is rather generally distributed through- 

 out the cranberry-growing sections of this country. Pycnidia have 

 been found on either leaves, flowers, or fruit in West Virginia, New- 

 no 



