GNOMONIA. 223 



epidemic disease of the cherry {Prunns acinm and F. Crrasus), 

 observed for several years past in Xorth Germany and else- 

 where. The fungus attacks the leaves, and there the mycelium 

 grows. The leaves wither prematurely, but remain all winter 

 hanging from the tree by a reddish-brown mycelium. I'ycnidia 

 and perithecia are produced in the leaves, the latter reaching 

 maturity in spring, when the two-celled ascospores are ejaculated. 

 Tlie pycnidia contain short conidiophores bearing hook-shaped 

 conidia. The fruit is also attacked, and ripens unequally, so 

 tliat the cherries are distorted ; then they crack and rot. 



Frank has succeeded in carrying out artificial infection. This 

 takes place in June, and immediately on germination the germ- 

 hypha produces an attachment-disc on the host-epidermis, whence 

 a hyphal filament penetrates the epidermal wall, grows through 

 the cell, and reaches an intercellular space. A thick septate 

 uiyetdium is formed and spreads, especially amongst the spongy 

 parenchyma. There is no stroma, and the peritliecia hibernate 

 on dry leaves. 



Frank recommends the plucking and burning of dead leaves 

 hanging on the trees. This must of course be done throughout 

 the whole district attacked. In one part of Prussia (Altenlande) 

 this precaution was taken twice each winter for two years, 

 with the result that the disease, which had long completely 

 ruined the cherry crop, disappeared, and the harvest increa.sed 

 to its former amoiiut. 



Gnomonia quercus-ilicis Berl.^ causes brown spots mi Lmvcs 



of (Jiinms Ilr.r. 



VALSEAE. 



Mamiania. 



Perithecia produced in a black stroma, from which their long 

 necks project. The asci have a thickened apex, and contain 

 eight oval hyaline sp(n'('s with one or two cells. 



Mamiania ( Gnomoniella) fimbriata Pers. (Britain and I'.S. 

 America). The stromata of this appear in summer as little 

 black cushions on the leaves of the hornbeam (Carpinus). The 

 perithecia are developed in these spots, and their long black 

 beaks projecting distinctly above the surface of the leaf cause 



iBerlese, Bhista di Patohijia verjefa/e, i. 



