10 MAINE AGRICUIvTURAIv SXPERIMI^NT STATION. I905. 



gypsum is formed, leaving a deep blue solution of hydrate of 

 copper. If desired, the spray may be applied immediately after 

 preparation, as the small amount of finely divided gypsum will 

 not interfere. Prepared in this manner, the solution contains 

 about the same amount of copper hydrate as the ordinary Bor- 

 deaux mixture. It may be diluted indefinitely with water with- 

 out a precipitate forming. The solution should be kept in well 

 stoppered bottles and is best if used within 48 hours after 

 preparation. 



In case complete solution of the copper hydrate is not obtained, 

 add a little more of solution No. 2 of sucrate of lime. As pre- 

 pared, the soluble Bordeaux is, because of the sugar, much more 

 expensive than regular Bordeaux carrying the same amount of 

 copper. In the experiments here reported the soluble Bordeaux 

 carried about one-half, one-fourth and one-seventh as much 

 copper as the usual mixture. 



The field of potatoes selected for the experiment was upon the 

 farm of Mr. Clarence A. Powers, Maple Grove. It was planted 

 to Green Mountains, and the rows were of such length that 12 

 rows made about an acre. The rows ran east and west. The 

 field was apparently quite uniform, and sloped slightly toward 

 the south and east. The potatoes were liberally fertilized, and 

 thoroughly cared for during the growing season. The soluble 

 Bordeaux as well as the regular Bordeaux mixture was applied 

 with a one-horse Getchell sprayer that was provided with a 

 powerful pump and an agitator that kept the solutions thor- 

 oughly stirred. Vermorel nozzles were used, so that with the 

 pressure obtained the materials were all applied in a fine spray. 



The arrangement of plots and their treatment was as follows : 



Plot A. Twelve rows (one acre) on south side of field, 

 sprayed with regular Bordeaux mixture. 



Plot B. Twelve rows (one acre) next north were treated 

 with soluble Bordeaux at such a rate that the copper applied at 

 each application was equivalent to about 2^ pounds of sulphate 

 of copper to the acre. 



Plot C. Twelve rows (one acre) next north were treated 

 with soluble Bordeaux equivalent to i^ pounds of sulphate of 

 copper each application. 



