GNOMONIELLA 173 



As the fungus is abundant on the blackthorn, wild plum, 

 and bullace, such should be removed from the neighbourhood 

 of young fruit-trees, which are liable to infection until ten 

 years of age. 



Massee, Gard. Chron., Sept. 27, 1902. 



,, Jonrn. Board. Agric, 9, p. 361 (1902). 



DITOPELLA (De Not.) 



Perithecia formed in the bark of the host, immersed, osti- 

 olum protruding ; asci many-spored, spores elliptical or 

 ovoid, subhyaline, continuous. 



Alder twig blight. The tips of the twigs are killed by 

 Ditopella fusispora (De Not). The bark of the injured parts 

 is of a red-brown colour, which contrasts strongly with the 

 green colour of the healthy portion of the shoot. The fruit 

 of the fungus, under the form of minute black dots, is 

 scattered over the diseased portions. 



Spores, 15-25 x 2-3 //.. 



Plowright., Gard. C/iron., June 17, 1899, p. 392. 



GNOMONIELLA (Sacc.) 



Perithecia sub-membranaceous, beak central or lateral ; 

 asci 8-spored ; spores elongated, continuous, hyaline, rarely 

 subfiliform ; paraphyses absent. 



Alder leaf spot. Klebahn has shown that the fungus 

 known as Leptothyrium alneum (Sacc), which occurs under 

 the form of minute, shining, black dots the perithecia on 

 yellowish spots on living alder leaves, is the conidial stage 

 of the ascigerous fungus (Gnomoniella tubiforviis, Sacc). 



Conidia sausage-shaped, curved; hyaline, 8*5 X 1*5-2 fi. 



Perithecia of ascigerous form develop on dead, fallen 

 leaves in the spring. Immersed, with a stout, long beak 

 protruding from under side of leaf; asci cylindric-clavate, 

 60-70X11 13 /x; 8-spored; spores hyaline, unsymmetrically 

 elliptical, T2-i5X5-6'5 /x. 



Klebahn, Zeiischr. Pflanzenkr., 18, p. 140 (1908). 



