The Black Rot of the GR.\.rE and Its Control. 403 



to about seven acres, was chosen for the experiment. This vineyard 

 is situated about 2 J miles east of Romulus and is under the direction of 

 Mr. H. B. Cushman. For several years previous nothing had been 

 picked commercially from the vineyard because the Rot had destroyed 

 the entire crop. During these years sections had been cultivated and 

 pruned but not sprayed. On one of these sections the plat was chosen. 

 It was thought that the Rot would be serious in this vineyard even 

 though the summer should be a dry one. This proved to be true. 



The area was divided into six plats, each consisting of seven rows and 

 equal in area to about one acre. Between each two plats was a check 

 row, seven in all, thus making the check rows also equal in area to 

 about one acre. (See map, page 402). It was found that these rows 

 did not make reliable checks since it is impossible, in spraying the adjoin- 

 ing rows, to prevent the spray from blowing on them, and consequently 

 these check rows received more or less of the mixture. In order to check 

 the results of these check rows and thus secure the most reliable check, 

 two solid check plats were chosen, one of them to receive cultivation 

 and the other to be left uncultivated. This plan enabled us to determine 

 the value of spraying and also the value of cultivation as factors in 

 the control of the Rot. 



As to the number of applications, at least four seemed necessary, 

 and we found in 1907 that six had given as good results as a greater 

 number. Our plan was to determine the most economical number of 

 applications within this range. 



It is important to determine the minimum strength of mixture that 

 will control the disease, since spraying materials are expensive. The 

 work of 1907 had shown that 5-5-50 gave as good results as stronger 

 solutions, consequently there was no need of going above that strength. 

 It was felt, however, that a weaker mixture would be equally effective 

 and therefore it was decided to use 4-4-50 in order to determine 

 whether it was strong enough. 



The work of the previous season had shown that the time of the 

 application for effective control depended largely on weather conditions. 

 One plat was planned in view of determining whether this was true 

 and, if so, what were the conditions which determine the time of appli- 

 cation. (See plat 4.) 



The general plan and map of the work for 1908 is given in Fig. 107. 

 In area each plat is equal to about one acre. The rows (seven to each 

 plat) are nine feet apart and the vines ten feet apart and each row 

 contains sixty-four vines. 



