ACCIDENTS, DISEASES, PARASITES. 181 



5th. Verdet gris. Georges Beucker*, of Montpellier, 

 recently recommended the use of verdet gris or bibasic acetate 

 of copper against mildew, used in the proportion of 1 part per 

 ] 00 parts of water. According to the author, the solution 

 should be prepared in the following manner: 



About 50 parts of dry granulated verdet gris are dissolved 

 in 500 parts of water three or four days before using, and the 

 mixture stirred as often as possible during this interval. 



The day the treatment is to be applied 20 parts of this 

 preparation are poured through a copper sieve into 200 parts 

 of water. These 200 parts of water contain 2 parts of verdet, 

 therefore the solution contains 1 per cent. This liquid is 

 applied with spray-pumps in the ordinary way. 



Experiments made at the School of Agriculture, Mont- 

 pellier, with verdet gris constantly gave results equal to 

 those obtained with Bordeaux mixture, and it proved to be 

 more adherent. 



6th. Sucrate of copper. Copper forms with sugar a 

 compound capable of preventing the development of mildew. 

 Michel Ferret proposed adding molasses to kydrocarbonate 

 of copper, and originated the following mixture : 



"Two parts of sulphate of copper are dissolved in 15 parts of 

 water ; 3 parts of commercial soda are added to this solution. 

 After the precipitation is completed one-fifth to one-half 

 part of molasses are added, and the mixture left for twelve 

 hours, after which 100 parts of water are added. 



" The mixture thus obtained is of a deep-green colour, easily 

 detected and very adherent ; the part dissolved by the sugar 

 acts directly when applied. The part precipitated prolongs the 

 action of the mixture by dissolving in drops of rain or dew. 



"Experiments proved this year (1889) that this new 

 mixture was more effective on grapes than those used so far." 



Experiments made with sue rate of copper in 1 890 at the 

 School of Agriculture, Montpellier, did not allow us to ascer- 

 tain its action on mildew, as this disease did not appear in 

 the experimental plots ; but the mixture did not remain on 

 the leaves as long as the mixture of Dauphinee or verdet gris. 

 It appears desirable, therefore, to wait for other trials before 

 expressing a definite opinion on the subject. 



Mode of application of cupric compounds. Cupric com- 

 pounds prevent the germination of the conidia or spores 



* Georgns Bencker was the first to suggest th* ue of verdet gris in 1886. See Progrts 

 Agricole, Montpellier, vol. xii, pasje 90, 1889 ; vol. xiv, page 510, 1890 ; and vol. xxvii, pjge 

 222,1897, [Truiisls.] 



