GRAPE-SPRAYING EXPERIMENTS IN MICHIGAN IN 1909. 5 



I, fio-. 2, B.) Ivot ap[)eared on the yoiinj;- lu'iries on July 5, and from 

 that date until the grapes were harvested there were only a few brief 

 periods that one could not find black-rot in all stages of development 

 on the fruit. The latest that it was seen developing cm the leaves was 

 September 29, when fresh spots were found rather abundantly on 



the younger leaves. 



EXPERIMENTS. 



The spraying experiments for the control of black-rot were carried 

 on in 1909 in the same general way as in previous years. A number 

 of different mixtures were used on separate plats in the vineyards in 

 which work Avas done, in order to determine their comparative value 

 as fungicides, as follows : 



(1) Bordeaux mixture, prepared with commercial copper sulphate, 

 fresh stone linic, and water, in the order given, was used according 

 to the following formulas : « 4-4-50 ; 4-3-50 ; 4-2-50 ; 3-2-50. 



(2) Xeutral copper acetate, prepared by dissolving 1 pound of 

 neutral copper acetate in 50 gallons of Avater. 



(3) Ammoniacal copper carbonate, prepared by dissolving G ounces 

 of copper carbonate in 3 pints of strong ammonia and adding it to 50 

 gallons of Avater. 



(4) Self-boiled lime-sulphur, prepared by putting 10 pounds of 

 fresh stone lime in a barrel and adding a little cold Avater; then 10 

 pounds of sulphur, and enough Avater to slake the lime into a paste. 

 After the lime had slaked, the mixture was diluted to 50 gallons. 



(5) Connnercial lime-sulphur, prepared by mixing 1 gallon of 

 commercial lime-sulphur Avash Avith 75 gallons of Avater. 



The tAvo ^"ineyards in which the work Avas done Avere the David 

 Engel \ incynrd. nef.r PaAv PaAv. I'ecently leased by Mr. Roy L. Tuttle, 

 in cooperation Avith whom the work Avas carried on, and the C. C. 

 Giddings vineyard, near LaAvton. Avhich Avas one of the vineyards 

 used in the experiments conducted in 1908. 



TIIK KXPERIMENTS IN MR. CIDDINGS's VINEYARD, NEAR LAAVTON, MICH. 



The vineyard of Mr. Giddings contains Concord vines trained after 

 the Kniff'en system. The plats Avere about one-third of an acre in 

 area. The check of the previous year '' Avas used, Avhich furnishes .some 

 data upon the effect of spraying the same vines for Iavo successive 

 years as compared Avith alloAving the grapes to go unsprayed for that 

 length of time. The mixtures Avere applied with the same geared 



" In writing formulas for Bordeaux mixture, the quantity of copper sulphate 

 is given first, lime second, and AA-ater last; for cxaniiile, 8-2-50 Bordeaux 

 mi.xture means 3 pounds of copi)er suli)hate. '2. ]miuiu1s of liiiic. and enough water 

 to mak(^ ."jU gallotis of the mixture. 



''See ■"Till' Cmiti'ol of IMaiU-Kot of tlie (inipe," Bulletin 155, Bureau of Plant 

 Industry. T. S. Dcpi. of .\irriculture. 

 [Cir. »;.".) 



