lo Feb., 19 1 2.] Vine Diseases in France. u-j 



Burgundy Mixture (Copper-Soda). 



The chief objection to this mixture is its rapid deterioration, especially 

 in hot weather. It must therefore be prepared in small quantities, as re- 

 quired. The usual formula is : — Copper sulphate, 2 lbs. ; crystallized 

 carbonate of soda (common washing soda), 2| lbs. ; and water, 10 gallons. 

 Owing to the variable composition of washing soda, it is better to proceed 

 according to the last directions given for Bordeaux mixture, checking 

 neutrality with phenolphthalein paper. The sheet quoted above recom- 

 mends the use of water free soda (Solvay soda) instead of washing soda. 

 Two solutions are made, one of 2 lbs. copper sulphate in 5 gallons water, 

 and one of i lb. of Salvoy soda in 5 gallons of water. The second is 

 poured into the first with constant stirring. 



Any dry spraying substance, from previous lots, causes rapid deteriora- ■ 

 tion ; all vessels must, therefore, be kept thoroughly clean. The addition 

 of sugar will have no effect in keeping it in good order, as with Bordeaux, 

 but cream of tartar or Rochelle salt may be used for the purpose; 2 ozs. 

 of whichever salt is preferred should be dissolved in the water for the 

 second solution before the Solvay soda is added. In other respects, the 

 preparation is the same. The addition of either of the above salts will 

 enable the copper soda mixture to keep for a few days. Any copper soda 

 mixture whicli shows a heavy greenish sediment is useless, since it will no 

 longer adhere. 



According to R. Brunett {Revue de Viticulture, 19th January, 191 1), 

 Burgundy growers were dissatisfied, last season, with copper soda, which 

 they have hitherto mainly used, and are preparing to adopt Bordeaux 

 mixture in future. 



Copper-Soap Mixtures. 



Owing to its alkalinity, soap can take the place of lime or soda in the 

 preparation of copper mixtures. Its action in lowering surface tension 

 augments the wetting power considerably, and this is perhaps the main 

 advantage to be derived from its use. Adherence is good whilst fresh, but 

 diminishes rapidly with keeping. Like copper-soda, copper-soap must be 

 prepared immediately before it is used. Equal quantities of copper 

 sulphate and soap powder are used. For a i| per cent, mixture this would 

 mean, for every 10 gallons of water, \\ lbs. copper sulphate, and \\ lbs. 

 powdered soap. Dissolve each substance in 5 gallons of water and mix 

 thoroughly, pouring soap into copper, not the reverse.* 



Copper- soap mixtures are not new ; they have been in favour in some 

 quarters since first recornimended by M. G. Lavergne at the close of the 

 last century, but they have not come into very general use. Se\-eral of 

 the proprietary spray powders, which merely require mixing with water to 

 be ready for use, are mixtures of soap and copper sulphate. 



Quite recently. MM. "\>rmorel and Dantony have recommended a new 

 aopp\?r-soapt which seems to have much to recommend it. It is of 

 colloidal nature; when diluted, it wets well and does not deteriorate on 

 keeping. It is prepared as follows : — 



Dissolve I lb. of copper sulphate in 10 gallons of water; dissolve 4 lbs. soan (free 

 from alkali in excess) in 10 gallons of water. Pour the copper into the soap (con- 

 trary to the usual practice). Opertain^ thus, instead of the usual voluminous, 

 grealsy precipitate of copper soap, one obtains an opaque, greeny-blue liquid, with 

 a surface tension as low as plain soap solution, which wets the bunches just as 

 alcohol would 



* I.. Dearullx . Progres Agricole, 24th .\pril, 1910. 

 t Revue de Viticulture, 1st June, 1911. 



