

BRIEFER ARTICLES 



THE PERFECT STAGE OF THE ASCOCHYTA ON 



THE HAIRY VETCH 



It is quite well known that species of the form-genus Ascochyta 

 produce a disease of the vetch, pea, and other leguminous plants. In 

 the autumn of 1908 I collected a number of affected pods of the hairy 

 vetch (Vicia villosa) which was growing on the farm of Cornell Uni- 

 versity. These were placed in a wire cage and partly covered by 

 some leaves and grass used as a mulch for Rhododendron maximum in 

 my garden. It was hoped that the perfect stage might be obtained. 

 During early May in 1909 the cage was taken to the laboratory, and 

 a few pods were found on which there were a number of perithecia 

 which proved to belong to the genus Sphaerella (Mycosphaerella), 

 although pycnidia of the Ascochyta were present on the same pods. 

 They were at some distance from the perithecia, and by using care it 

 was not a difficult matter to obtain an abundance of ascosppres for 

 making pure cultures in bean pod agar, and also for inoculation of 

 vetch seedlings. 



The germination of the ascospores was studied and the growth of 

 the colonies was observed up to the formation of pycnidia and pycno- 

 spores identical with those formed on the vetch pods, evidence that this 

 Sphaerella was the perfect stage of the Ascochyta of the vetch. Inocula- 

 tions of vetch seedlings were made with pycnospores obtained in pure 

 culture from sowings of ascospores. These were somewhat slow in 

 taking, but on May 18 a few brown spots appeared on the stems, and on 

 May 24 some of the leaves were dead and pycnidia of the Ascochyta 

 were present. 



On May 13 ascospores taken directly from the pods of the vetch 

 were sown on vetch seedlings. On May 17 brownish depressed spots 



* 



were present on the stems. By May 18 these spots had encircled the 

 stem and the terminal shoot was thus killed. Again on May 15 asco- 

 spores were placed on young vetch seedlings. On May 18 a few of the 

 leaves were dead and pycnidia were present. By May 22 the disease 

 had spread somewhat and more pycnidia of the Ascochyta were formed. 



537) 



r e inoculated with asco- 



[Botanical Gazette, vol. 54 



