^ 



150 



MISSOURI BOTANICAL GARDEN. 



decomposed tissues takes place. 



apparently 



growin 



hastened by a dissolution of the cellulose walls by an enzym 

 secreted by the fungus. The younger, 

 of the plant are. favorite places for attack. The petioles 

 of the leaves are often rotted away at the base, the leaves 

 droop, and the fungus grows down through each leaf, rot- 

 ting it, often forming sclerotia on the thinner portions. 



Sometimes older caul r .__„ «„•»«. „,. 



and rotted off, before the head becomes diseased. 



Pure 



cultures of the fungus were obtained from the 



cauliflower in February, 1904, and grown in potato, 



rice 



and agar tubes. 



These all formed prominent sclerotia in 

 a few weeks, only a few being produced in each tube. At 



B 



tained 



& 



compari- 



son. These bore numerous smaller sclerotia. Sclerotia 

 from old, dry cultures of both species were placed in pots 

 of soil, previously sterilized in an autoclave at 15 pounds 

 pressure for three hours. They were barely covered with 

 the soil and placed in a moist room, and kept in moist soil 

 for about three months. In seven weeks the Sclerotinia 

 sclerotia threw out from each a number of brown or gray 



stalks, 



upon the stalks. 



a convex cup, bi 



more 



d 



haped 



ped 



wh 



mature. In color they were a light brown. 



The apothecia contained eight-spored asci. The asco- 

 spores were slightly" granular, but without guttules. In 

 poured agar plates they germinated readily and developed 

 rapidly into dense white fluffy colonies. T ie mycelium 

 was destitute of conidia at every stage. In less than two 

 weeks sclerotia were formed on colonies transferred to potato 



or rice tubes. 



th both the ascospores from 



the apothecia and the mycelium from pure cultures pro- 

 duced the typical rot of the cauliflower, control plants 





