TWO EPIDEMICS OF POTATO BLIGHT AND ROT. 1 75 



and it is doubtful if a large excess of lime adds to the fungi- 

 ciflal value of the mixture. Experiments have shown, however, 

 that an excess of lime materially decreases the adhesive quali- 

 ties of the mixture. "Those mixtures are best in adhesiveness, 

 and in efficiency, in which the approximation of equal parts of 

 copper sulphate and lime are maintained." * 



One season's experiments conducted at this Station indicate 

 that the prepared or hydrated lime will give equally good results 

 as stone or lump lime used in making bordeaux mixture, judged 

 by the appearance of the foliage and by the yield per acre at 

 harvest time.** 



Guess work is very frequently substituted for weights and 

 measures, and the amount of" lime and copper sulphate, or the 

 stock solutions of these ingredients in a given amount of spray 

 varied with the ability or judgment of the maker. One remark- 

 able case was found where the individual prepared his stock 

 solution of copper sulphate as follows : 50 pounds of the crys- 

 tals were placed in a sack and suspended in a 50 gallon barrel 

 of water in the usual way and allowed to dissolve. Then as 

 fast as 5 or 10 gallons of this stock solution were taken out an 

 equal amount of water was put in to replace it and this con- 

 tinued through the season. From time to time another 50 

 pounds of blue vitriol would be dissolved in the liquid. Thus 

 it will be seen that except for the first lot of stock solution 

 removed none used was of standard strength throughout the 

 season. Bordeaux mixture prepared from such stock solutions 

 cannot be exj^ected to produce satisfactory results. 



Properly prepared bordeaux mixture should contain 5 pounds 

 each of copper sulphate and lime to 50 gallons of water, and the 

 ingredients should be weighed and measured. The copper sul- 

 phate should be dissolved and the lime slaked in separate ves- 

 sels. Never four concentrated solutions of lime and copper 

 sulphate together. The most adhesive and satisfactory mixture 

 is prepared by diluting each strong solution with half of the 

 water and then these two dilute solutions should be united 

 quickly and thoroughly mixed at once. Full directions for 

 preparing bordeaux mixture are contained in a circular entitled 



* Crandall, C. S. 111. Exp. Sta. Bui. 13S, p. 218. 



** Woods, C. D. Me. Expt. Sta. Bui. 98, p. 191-200 (1903V 



J 



