GRAPE-SPRAYING EXPERIMENTS IN MICHIGAN IN 1909, 15 



in wliirh the fungus has become thoroughly established and very de- 

 structive, there being a diti'erence of 86.4 i^er cent between the amount 

 of rot on the nnsprayed checU and the best sprayed plat. 



In Mr. Giddings's vineyard, which had been thoroughly sprayed 

 the previous year, there was practically no loss from black-rot on 

 the portions sprayed with P.onlcaux mixture, v/hile the loss on the 

 check was 39.8 per cent. 



The best fungicide used was Bordeaux mixture, and of the differ- 

 ent formulas for this the 4-?>-50 has always given good results. The 

 3_2-50 mixture gives promise of being a good fungicide, as about 

 the same results were obtained with it as with the 4-3-50 formula. 

 Tt may prove as efficient as the 4-3-r)0 formula, l)ut should be tested 

 more thoroughly. 



Of the two nonstaining compounds used, neutral copper acetate 

 and ammoniacal copjoer carbonate, the former was found to be the 

 better fungicide. For (■om])arison, see Plate III, figures 1 and 2. It, 

 however, injured the foliage badly when used throughout the season, 

 but seemed to have no ill effect as a final application. 



The lime-sulphur compounds are not suitable fungicides for grapes, 

 the self-boiled because it does not control the rot, and the commer- 

 cial lime-sulphur because it does not control the rot as Avell as the 

 Bordeafix mixture and is very injurious to the vines. 



Of the adhesive compounds used, the results with resin-fishoil soap 

 were better than those Avith the iron sulphate. The addition of 2 

 pounds of soap to 50 gallons of the mixture used in the last appli- 

 cation seems to do as much good as where it is added in all sprayings. 



The disease can be controlled with five applications of 4—3-50 Bor- 

 deaux mixture thoroughly applied, soap being used in the last appli- 

 cation. " Thoroughly applied " means that every portion of the vine, 

 and especially the foliage and fruit, receives a coating of spray 

 mixtun 



Approved : 



James Wh.son, 



Secretary of Ar/rleulture. 



Wasiiixoton, I). C'., June 10, 1910. 



o 



[Cir. 65] 



