46 The Spraying of Plants. 



parts of the country. The second treatment should be made 

 three weeks later, and a third again in three or four weeks. In 

 case of necessity a fourth should be made early in September. 

 He further advised that the material should be applied lavishly, 

 during the first treatment in particular, and that the leaves 

 should be thoroughly covered. He also said that it should be 

 made a point to cover the young grapes, a recommendation 

 which does not appear to have been made before. When the 

 Bordeaux mixture was first coming into use, Millardet said one 

 should be careful not to strike the grapes, and he also made the 

 statement that if only a small amount of the mixture fell upon 

 the leaf it would still afford ample protection. Experience evi- 

 dently had shown that the work cannot be done too thoroughly. 



Patrigeon did not favor the use of powders for the following 

 reasons : they require moist foliage to adhere well ; they can be 

 applied only when the air is still ; more applications have to be 

 made ; and the vines are not so well protected. 1 



He considered as entirely unfit for use upon foliage the simple 

 solution of copper sulphate, and the eau celeste of Audoynaud, 

 because they burned the leaves. The materials which could be 

 advantageously applied were reduced to those mixtures or solu- 

 tions that contain copper in the form of the hydrate (hydrate 

 oxide} or of the hydrocarbonate. There were several of these 

 already in use. 



Patrigeon was the first to use and to advise the use of the 

 ferrocyanide of potassium as a test for determining the proper 

 amount of lime required in making the Bordeaux mixture. 2 

 His directions were to add to the Bordeaux mixture a few 

 drops of a 20 per cent solution of this chemical. So long as 

 dissolved copper exists in the mixture, the addition of the 

 fsrrocyanide of potassium causes a reddish brown precipitate 

 to appear. Lime should be added till no change takes place 

 when the reagent is added. Some vineyardists used blue 

 litmus paper for the same purpose. 3 



During these years the diseases which affect grapes received 

 by far the most attention. Jouet and Prillieux were among 



1 Jour. d'Ag. Prat. 1890, May 8, 660. See also, "Reunion publique des 

 Viticulteurs du Midi," held at Montpellier, March 4, 1890. 



2 Ibid. May 15, T01. 



a A. Petit, L& Progres Agrieole, 1890, June 1, 441. 



