EXPERIMENTS IN THE CONTROL OE GRAPE ANTHRACNOSE. 



on its treatment abroad. As the climatic conditions of American 

 and European vineyards differ, as well as the varieties of grapes 

 usually grown in them, it was thought that it might be necessary to 

 modify the treatment of the disease as practiced in Europe, in order 

 to adapt it to American vineyards. The experiments described in 

 this circular were accordingly taken up by the writer, under the direc- 

 tion of Dr. C. L. Shear, Pathologist, of this Bureau, to see whether 

 the disease could be controlled in this country by the use of a solution 

 of iron sulphate and sulphuric acid in water, which is employed 

 extensively in Europe. It was also considered worth while to 

 experiment with applications of other fungicides to the dormant 

 vines and to try the effect of summer sprays in comparison with 

 the iron-sulphate and sulphuric-acid treatment mentioned. 



EXPERIMENTATION. 



The experiments which are here reported were conducted at 

 Lawton, Mich., in a vineyard of Champion grapes belonging to Mr. 

 John Robinson. In this vineyard in 1909 about two-thirds of the 

 fruit had been destroyed and the young wood seriously injured by 

 anthracnose. The vines selected for experimentation were a block 

 of about 600 where the disease had been the most severe. This block 

 was divided into nine plats, seven of which were to be treated and 

 two to remain untreated as controls. The order in which the treated 

 plats and controls w r ere arranged is shown in Table I. 



Table I.- 



-Treatment (riven plats of grapevines at Lawton, Mich., in 1910, 1911, and 

 1912 and the results obtained in 1911 and 1912. 



[Cir. 105] 



