NOTKS UPON CKLERY. 205 



August 15 a second application was made as before, except that a 

 weaker solution* of the copper carbonate was used. A heavy 

 rain followed in a short time, and little result could be anticipated 

 from this application. I was then necessarily absent from Ithaca 

 for a month, and further applications were not made. Thus the 

 work was left in rather indefinite shape to await earlier experi- 

 mentation another season. The results at least suggest that car- 

 bonate of copper may be used to advantage. At the time of set- 

 ting, young plants (leaves only) might be dipped in a weak 

 solution of this fungicide, and subsequently the growing plants 

 sprayed at intervals of two weeks with a solution of the same 

 strength. Any of the spraying apparatus used for potatoes would 

 sufiice for this work. Growers should be extremely careful not 

 to set plants which are in any way spotted in the seed bed ; and 

 if the sets are purchased, use none in a lot showing any indica- 

 tion of the disease. 



The fact that the spores of the fungus have been found to ger- 

 minate after passing the winter on the dead leavesf of the previous 

 season will suggest to progressive growers the need of destroying 

 all refuse matter and diseased material. Bits of diseased material 

 will remain, however, and this alone indicates that rotation is a 

 good thing where it is practicable. Again, the fungus spreads 

 rapidly upon wilted plants, especially in muggy weather, so that 

 care should be taken to collect and destroy the product of sucker- 

 ing. A disease of the common wild parsnip so closely resembles 

 this celery blight that many botanists consider them forms of the 

 same disease ; so it may be well to rid the borders and fence rows 

 of the wild parsnips. 



Artificial Cultures of the Fungus. 



The length of the fruiting hyphae and conidia are largely dependent upon 

 the amount of moisture in which they are developed, and probably some- 

 what inversely upon the vigor of the leaf. On leaves placed in a moist 

 chamber the condition is much as represented in Figure 48, c and d (pro- 



" This formula consisted of 



Copper carbonate 6 ozs. 



Ammonia water ( 26° ) 2 pints. 



Water 45 gals. 



t Report U. S. Dept. Agriculture, 18S8, p. 399. 



