Solutions of Copper in Fimgicides. 41 



The Bordeaux mixture still retained its supremacy wherever 

 it was used in comparative trials. Prillieux made one of the 

 most satisfactory tests in this direction in his work on the 

 black rot in 1888. 1 He used, in addition to the Bordeaux mix- 

 ture, eau celeste, pure solutions of copper sulphate, sulphostea- 

 tite, and Carrere powder. The relative value of these materials 

 was in the same order as they are here mentioned. The vines 

 treated with the powders were attacked by the disease appar- 

 ently as much as those which had received no treatment. The 

 dates of treatment apparently had some effect on the efficiency 

 of all the materials. The first applications seem to have been 

 made too late, for Frechou said 2 he had obtained excellent 

 results from the use of sulphosteatite and also of the Carrere 

 powder. Lasserre controlled 3 the black rot well by applying 

 only 1 kilo copper sulphate and 1| liters ammonia in 1 hecto- 

 liter of water. His first treatments were made April 28, and 

 he ascribes his success to the timely beginning of the work. 

 He believed that the success of Prillieux might have been 

 even more complete if his applications had been made earlier 

 in the season. 



During 1889 a new problem was occupying the minds of the 

 leading French experimenters. It was the general belief that 

 the Bordeaux mixture was too slow in its action, since practi- 

 cally none of the copper contained in it was soluble in pure 

 water. Another reason was advanced for this tardy action of 

 the Bordeaux mixture: Millardet and Gayon said 4 that no cop- 

 per could be absorbed by foliage until all the excess of lime 

 had been formed into the carbonate. This process was- sup- 

 posed to require from a week to a week and a half. They 

 said 5 that the change took place faster during a fine rain, bufc 

 even then it appeared that the immediate action of the mixture 

 as soon as applied was, at the best, but very slight. The greater 

 the excess of lime, the longer appeared to be the time required 

 for the copper to enter into solution. 



1 Jour. d'Ag. Prat. 1S83, Dec. 20, 898. 



2 Ibid. Dec. 13, 851. 



3 Ibid. loc. cit. 



* Ibid. 1890, Feb. 20, -27-2. 



5 " Nouvelles Recherches sur le Developpement et le Traitement du Mildiou et 

 de TAnthracnose," Millardet et Gayon, 1887, 8-18. 



