DISEASES OF CELERY 87 



in this manner. This is an easy way to dispose of 

 the refuse, but at the same time a dangerous pro- 

 ceeding if the land is to be devoted to celery the 

 following season. 



Pithiness of Celery. — The term ''pithy" is em- 

 ployed to designate any form of soft or hollow stem 

 in the mature celery plant. In a bed of celery plants 

 there are frequently a few of a bright green color 

 which outgrow the others and usually have hollow 

 stems. These rank-growing plants are called 

 "sports" or "rogues," and they can generally be de- 

 tected when the plants are removed from the plant 

 bed. Seed from a poorly-selected strain of celery 

 will frequently produce a large percentage of plants 

 that do not differ in appearance from the others, but 

 which develop pithy or hollow stems during the 

 growing season. 



A special strain or type, such for example as the 

 Golden Self-blanching variety, is obtained by cross- 

 ing and a certain number of the plants are con- 

 stantly reverting to the original parent types. In 

 order to keep the strain pure it is necessary that 

 the seed growers should continually cull out all 

 plants that do not conform to the desired type. The 

 French growers of celery seed have attained a high 

 degree of perfection in maintaining pure strains, 

 and until it has been shown that American-grown 

 seed will produce as good results as the French it 

 will be desirable to plant only the imported article. 

 At the present time about 85 per cent, of the Golden 

 Self-blanching celery seed used in America is pro- 

 duced in France and adjacent territory. Seed grown 



