312 STATE BOARD OF AGRICULTURE. 



"*. FOREWORD. 



The results of spraying experiments to control the black rot of the 

 grape in Michigan are presented in this bulletin. 



These experiments were made by Messrs. Shear and Hawkins of the 

 Bureau of Plant Industry, U. S. Department of Agriculture, and the 

 account of their work and results turned over to this Station for pub- 

 lication by Dr. B. T. Galloway, chief of the Bureau of Plant Industry. 



It is hoped that the information here presented will be of value to the 

 grape growers in sections where the black rot is a serious trouble. 



R. S. SHAW, 



Director. 



GRAPE SPRAYING EXPERIMENTS IN MICHIGAN, 1907-8. 



BY C. L. SHEAR AND LON A. HAWKINS. 



Special Bulletin No. 49. 



In 1906, so far as we could learn, but six sprayers were in use in the 

 Lawton grape belt. Interest in spraying and confidence in its results 

 have so increased that most of the growers have secured sprayers and 

 are in most cases satisfactorily controlling the black rot. In the sum- 

 mer of 1908 at least 200 spraying outfits were found in use and perhaps 

 there were others of which we did not learn. Thirteen different kinds 

 were represented. 



The work of 1907 was commenced in two vineyards in the vicinity of 

 Paw Paw, but in one vineyard, that of Mr. J. M. ToAvers, it was dis- 

 continued on account of partial loss of the crop by frost and insects. 



The work in the other vineyard, that of Mrs. Emma R. Smith, was 

 continued throughout the season. This consisted of Concord vines about 

 2.5 years old, trained after the Knifiin system with the rows running 

 north and south. The fruit the previous season had been almost totally 

 destroyed by rot. Four plats adjoining each other were selected. The 

 three sprayed plats contained about .46 of an acre each, and the check 

 .115 of an acre. 



The fungicides used were as follows: 5-5-50 Bordeaux; 4-4-50 Bor- 

 deaux; .3-3-50 Bordeaux. For the sixth and seventh applications, Bur- 

 gundy mixture, composed of 1 lb. copper sulphate and II/2 ^^^- sodium 

 carbonate to 50 gallons of water, was used in order to avoid too much 

 "staining of the fruit. The work was done with a carbonic acid gas 

 sprayer. (See Plate I, Fig. 1). The first applications w^ere made with 

 fixed nozzles and the last three with trailers, the nozzles being directed 

 by hand. In order to determine the percentage of rot present on the 



