Family Leguminosae 277 



Symptoms. On the stem the trouble appears as 

 numerous elongated lesions. These spread to such 

 an extent as actually to girdle the affected stem. On 

 the leaves are formed oval spots, grayish in the center, 

 and limited by a dark band. The pods too become 

 badly attacked and the symptoms there resemble 

 those on the stems. The disease works its way from 

 the pods to the seed within. 



The Organism. The causative fungus has two 

 spore stages. The pycnidia bear the hyaline, two 

 celled spores and are formed within the dead tissue of 

 the affected stems, leaves, or pods. The pycnidial 

 stage is known as Ascochyta pisi Lib. The winter or 

 ascospore stage has only recently been discovered 

 by Stone, 1 who found it on pods and stems previously 

 affected, and on culture media. The fungus may be 

 carried from year to year as dormant mycelium within 

 the seed, or in the ascospore stage. 



Control. Seed treatment will not be of any value 

 since the fungus is hidden within the seed. No out- 

 side treatment is capable of reaching the parasite 

 within. Seed should be secured from localities 

 known to be free from the disease. Rotation of 

 crops is also recommended. Giving the field a 

 rest from peas or hairy vetch for at least three 

 years is recommended. In badly affected local- 

 ities, susceptible varieties, such as French June, 

 Market Garden, American Wonder, should be dis- 

 carded. The Alaska variety is claimed to be more 

 resistant. 



1 Stone, R. E., Annates Mycol., 10 : 564-592, 1912. 



