LAESTADIA. 217 



found right on into autumn, even throughout the winter. 

 Hibernating sclerotia are also produced, the cells of which grow 

 out directly into septate conidiophores with oval conidia. 

 Perithecia, externally resembling pycnidia, are formed in May 

 and June on the fallen berries of the preceding year. The 

 asci have gelatinous walls, which swell and burst so as to 

 ejaculate their spores. Viala and Kavaz successfully infected 

 living grapes by means of the larger conidia, and also by 

 the germinating ascospores. 



The disease is one of the most dreaded in America. It has 

 been found also in Europe, having been observed in France 

 since 1885, though not as yet in Germany, Switzerland, Italy, 

 or Spain. Moist situations are favourable to it. As with 

 other diseases of the vine, the various varieties have different 

 powers of resistance, and a judicioiTS selection of varieties may 

 prove a good preventive measure. According to Viala, the 

 black-rot is found in the United States on both wild and 

 cultivated vines, but never on the fruit of Vitis rupestris, V. 

 Berlancieri, V. cinerea, V. Ziusecomii, V. Monticola, and V. 

 candicans, and very rarely on their leaves. The "vine-stocks" 

 themselves suffer little or nothing from the disease. Eathay 

 says that Vitis riparia, V. rupestris, and V Solonis, so im- 

 portant as grafting-stocks, are seldom affected ; the green 

 shoots of other species, however, may be attacked and the 

 disease be transmitted through the graft-slip. 



For combating the disease, Galloway, Prillieux, and I'Eeluse 

 recommend Bordeaux mixture.^ 



Laestadia buxi (Desm.). The perithecia of this species are 

 found as. tiny points on yellow spots on the lower surface of 

 green leaves of box. This fungus, regarded by Desmazieres as 

 saprophytic, is said by Briosi and Cavara to be parasitic. 



PLEOSPOREAE. 



Physalospora. 



The perithecia are formed under the epidermis, but are 

 otherwise devoid of covering ; they contain asci and paraphyses ; 

 the spores are one-celled, and ovoid or elliptical. 



^For details see Itathay (loc. cit.), the American bulletins, etc. 



