93 



On one of the branches of the Cosmia numerous peritheca were found, 

 black and flattish, about 400/x across, often elongated with the drying 

 of the tissue in which they were imbedded. These bore strongly bi- 

 locularly marked spores T8-2*9 x 5*2-7*4^, and averaging about 3 x 

 6/ot, being rather rod-shaped with rounded ends 

 and sometimes not quite straight. 



All the stems were covered with the growth of 

 Botrytis, probably B. vulgaris. 



A number of species of Botrytis are known to 

 be associated with diseased conditions of various 

 useful plants, and are believed in some of the 

 cases to be the actual cause of the disease. In 

 other cases it is uncertain whether they are 

 cause or merely accompaniment. No previous 

 case is known to me of Botrytis on Cosmia in this 

 country, and it is not possible for me to say from 

 the specimens sent whether this fungus is the 

 cause of the plants dying off as described. 

 There was no doubt that the stems examined 

 were thoroughly infested, but whether or not 

 the fungus was the prime cause the material at 

 hand did not permit me to say. 



Fig. 106. Terminal portion of 

 one of the branches of the 

 fungus shown in Fig. 105, 

 more highly magnified. 



X400 



Fig. 105. Botrytis found 

 growing on stems of 

 Cosmia. The specimen 

 shown was one of the 

 smaller growths men- 

 tioned in the text. 



Outbreaks of Botrytis are usually found only 

 on rank growths in damp places, and the fungus 



appears only after the plants are beyond recovery, so that in the past 

 it has been the custom to describe the species of this genus as growing 



on " dead and decaying matter." This 

 may, however, have been a mistake, 

 in fact certainly was a mistake in 

 some cases. 



Remedies. Examine the plants and 

 ascertain what are the first symptoms 

 of the disease ; then pull up and des- 

 troy all plants that show any such 

 symptoms. Unless this is done it is 

 probable that the disease will spread 

 to other Cosmia plants, and to plants 

 of other varieties. Spraying with Bordeaux mixture has been shown 

 to be effective against some species of Botrytis, and may be tried with 

 hope of success in this case. 



Fig. 107. Terminal por- 

 tion of the aerial hypha 

 of the Botrytis shown 

 in Fig. 105, with the 

 spores removed ; 

 showing the recep- 

 tacles on which the 

 spores are clustered. 



