DISEASES OF CELERY 83 



knot seems to appear on plants growing on soils 

 which have been heavily manured shortly before 

 planting to celery. Very little is known about this 

 disease, but, as a remedy, it may be desirable to 

 devote the land to some other crop for two or three 

 years. 



Prevention and Control of Celery Diseases. — 

 While there are no specific remedies for the diseases 

 of celery when they become established, consider- 

 able may be accomplished by way of preventing and 

 controlling them. If celery is being grown on a 

 large scale it will be advisable to begin the pre- 

 ventive measures while the plants are in the plant 

 bed, and continue the treatment until the blanch- 

 ing process begins. Thorough spraying every ten 

 da3^s or two weeks with mixtures containing cop- 

 per, especially ammoniacal carbonate of copper and 

 Bordeaux mixture, will generally be sufficient to 

 prevent the diseases getting started. As a result 

 of experiments conducted at the Maryland agricul- 

 tural experiment station by Dr. C. O. Townsend ^ it 

 was demonstrated that shading was of some assist- 

 ance in combating the blight of celery, but that com- 

 plete immunity was obtained by spraying frequently 

 with the ammoniacal carbonate of copper si^lution. 

 This solution is prepared by dissolving i ounce 

 of copper carbonate in just enough ammonia water 

 to completely dissolve the copper and then dilute 

 to 9 gallons with cold water. The strength of 

 commercial ammonia water varies so greatly that 

 no definite amount can be given, but it is generally 



1 Maryland Expr, Sta. Bui. No. 74. 



