SCLEROTINIA 267 



numbers of sclerotia, varying in size from a turnip seed to that 

 of a pea, white, then black externally. When the stem is solid 

 the sclerotia are formed in its substance, and visible on the 

 surface. If diseased stems are allowed to lie and decay on 

 the ground, or even if they are placed on a heap in some out- 

 of-the-way corner, the sclerotia remain on the ground when 

 the stems decay, and the following spring give origin to 

 several brown, funnel-shaped ascophores borne on long, 

 slender stems. The spores from these fungi infect plants on 

 the spot, or are blown about by wind, and start the disease in 

 a new locality. 



In the case of plants producing tubers or fleshy roots, as 

 mangolds, turnips, potatoes, etc., the mycelium also passes 

 downwards into these parts, and eventually forms sclerotia, 

 more especially if sweating occurs after storing. If such 

 infected tubers, etc., are planted disease follows. 



It is not definitely known as to whether a Botrytis condi- 

 tion s present. De Bary, who first accurately studied the 

 fungus, considers that there is no Botrytis stage. Other 

 investigators, however, state that this phase does occur. 

 When the spores of the ascophore fruit first germinate, the 

 mycelium cannot directly attack living plants as a parasite, 

 but requires to live for some time as a saprophyte, obtaining 

 its food from humus, and afterwards passes on to the para- 

 sitic condition. 



The sclerotium is usually elongated, and sometimes is 

 2 cm. long, although generally shorter. From 1-4 ascophores 

 spring from a sclerotium, at first closed, then funnel-shaped, 

 finally almost flat, pale brown, 3-7 mm. across. Spores 8 in 

 an ascus, elliptical, 9-13 X 4-6 /*. 



Diseased stems should be burned, and not allowed to lie 

 about, for the reasons given above. In flower-beds, etc., 

 where this disease has previously existed, two inches of the 

 surface soil should be removed, and replaced by fresh soil 

 mixed with a little quicklime. Green stable manure favours 

 the disease. 



De Bary, A., Bot. Ztg., 1886, p. 458. 



Drooping disease of paeonies. A very injurious parasite 

 that has been called Sclerotinia paeoniae (Massee), but which 

 may not eventually prove to be a distinct species, often causes 

 the stems of paeonies to droop and die within the course of 



