1893.] PUBLIC DOCUMENT — No. 33. 223 



merely the practice of what should be ruling principles in 

 every greenhouse, cleanliness and watchfulness. 



In conclusion, it may be of interest to review briefly the 

 Ivnown parasitic species of Sclerotinia. We need notice only 

 those which are capable of really parasitic life, and are thus 

 truly disease-producing fungi. Sclerotinia Libertiana F'k'l., 

 the above-described species, was one of the earliest studies. 

 Our first exact knowledge of it is due toDeBary,* Brefeldf 

 and Mattirolo,$ who described the sclerotia and the perfect 

 form, while later DeBary § worked out the very interesting 

 conditions on which its parasitic life depends. He cultivated 

 it on a great variety of plants, including the turnip), l)eet, 

 carrot, radish, potato, petunia, zinnia, l)ean and others. 

 Brefeld found it attacking the Jerusalem artichoke, and 

 Frank || observed a disease of rape produced l)y it. It is 

 probal)le, too, that the disease of hemp oliserved l)y Ticho- 

 .mirofi" 1[ in Russia is due to the same species. The cucumber 

 has been found by Smith** to ])e attacked by a fungus which 

 he identified as Botrytis vulgaris, l>ut which he regarded as 

 only a saprophyte. It was })robaljly the conidial stage of 

 this Sclerotinia, and the discovery of its perfect form on the 

 same host is therefore very natural. Many additions to the 

 list of its host-plants are likely to be made. 



Sclerotinia Fuckeliana DeBary is one of the best known 

 of these forms. It attacks especially the leaves and fruits 

 of the grape vine in Europe, and is found on the herbaceous 

 parts of various plants, chiefly in its conidial form, known 

 as Botrytis cinerea. Although, as in Scl. Libertiana, the 

 conidial form usually reproduces itself persistently, the 

 sclerotia give rise under fiivorable conditions, when just 

 matured, to the Botrytis form. When older, they })roduce 

 the spore cups of the perfect form. These facts make the 

 demonstration of the connection of the two forms much 

 easier than in Scl. Libertiana. A disease of onions de- 



* Morphologie and Physiologic der Pilze, pp. 35, 60, 201 : 1866. 



fBotan. Unters. ober Schimmelpilze, IV., p. 112: 1881. 



J Nuovo Giornale Botanico Italiano, XIV., 200 : 1882. 



§ Botanische Zeitung, 1886, Nos. 22-27. 



II Die Krankheiten der Pflanzen, p. 530 : 1880. 

 % Bulletin Soc. Naturalistes de Moscou : 1868. 

 ** Gardeners' Chronicle, XXV., p. 173 : 1876. 



