274 SEVENTEENTH AND EIGHTEENTH 



in many sections of the state the entire crop of cucum- 

 bers and muskmelons has been destroyed. 



Leaf Mold {Alternaria hrassicae, var. nigrescens Pegl.). 

 This disease has also occurred on muskmelons. It can be 

 distinguished from the blight by the lack of angularity in 

 the spots produced. 



Cabbage Diseases. 



Club Root (Plasmodiophora brassicae Wor.). This dis- 

 ease has been found in several widely separated sections of 

 the state. It produces gall-like swellings on the roots, due to 

 the abnormal development of the host tissues. The plant 

 is greatly weakened and heads poorly, if at all. The cause 

 of the disease is one of the slime molds. These are peculiar 

 organisms that in one stage of their life closely resemble 

 the lower animal forms, but in other stages take a form and 

 a manner of living that seem to make it necessary to call 

 them plants. The parasite may live in the soil for several 

 years and cabbage set where the disease existed the previous 

 year are almost certain to be infected. See (b), plate 16. 



Celery Diseases. 



Leaf Blight (Cercospora apii Tres.). This is a very 

 serious pest of gardeners. The fungus produces brown 

 spots on the leaves, often causing them to turn yellow and 

 take a sickly appearance. 



Bean Diseases. 



Anthracnose [CollctotricJmni lindeiiutthianiDn (Sacc. et 

 Magn.). Bri. et Cav.]. This fungus may attack the leaves 

 of the host but is more common on the pods. Here it 

 produces dark spots with a reddish border. The fungus 

 spreads through the pods to the seeds, producing brown or 

 vellowish discolorations on these. The disease has been so 



