132 MASSACHUSETTS HORTICULTURAL SOCIETY 



Diseases of Indoor Sweet Peas. 



The following are some of the more important diseases which 

 attack greenhouse sweet peas. 



Root rot, Corticum ragum B. and C. 



This trouble is of considerable importance to greenhouse men. 

 The disease may destroy the entire stand, or cause it to be uneven, 

 thus necessitating several resowings. Severely infected plants 

 have practically no root system. In less infected plants only one 

 or two rootlets may be destroyed. The fungus produces a brown- 

 ing effect of the root before total destruction sets in. In very early 

 stages of infection the seedlings are seen to have a wilted appear- 

 ance; as the disease progresses the infected seedlings fall over and 

 collapse. The fungus is not confined to the roots alone. It is 

 often seen to work its way up the stem and produce a constricted 

 area marking it off from the healthy part. The fungus being a 

 soil organism is usually introduced with manure, infection taking 

 place at any part of the roots or stems. In the latter case reddish 

 sunken spots are observed at the base. Root rot is primarily a 

 seedling disease, although older plants, too, may be affected. Such 

 plants linger for some time and are valueless. Corticum vagum is a 

 soil fungus which attacks a number of other greenhouse as well as 

 outdoor plants. In this case, the organism either produces a 

 damping off among young seedlings, or deep cambium lesions on the 

 stem. With sweet peas the injury is the same. Root rot is intro- 

 duced in the greenhouse with infected soil or manure. Over water- 

 ing and a sour condition of the soil favors the disease. 



FusARiUM Wilt, Fusarium latkyri Taul). 



This disease is of much greater importance to greenhouse men 

 than root rot. The writer has known of instances where the dis- 

 ease has ruined the entire crop of indoor sw^et peas. After several 

 resowings, the owners gave up in despair the attempt to grow it 

 further. Florists should do everything to prevent its introduction 



