GRAPE-SPRAYING EXPERIMENTS IN MICHIGAN IN 1909. 13 



shown in Plate I, figure 2, .1, while in the other plat there Avere 4.3 per 

 cent of the grapes destroyed by rot (see PI. I, fig. 2, B), giving a 

 difference of 8().4 per cent as the value of spraying. Practically the 

 difi'erence was 95.7 per cent, as none of (he grapes on the check were 

 harvested. Tlie cost of spraying per acre in 1000 was found to be as 

 follows: 



Table V. — Coxi of Nprai/iiui I (icic irilh .'i-:i-50 lionleauc mixture. 123 gaUons 



Jiciiif/ (ipiilicd. 



Copper sulphate, 10 pounds, at TiJ cvuts $0.55 



Liuip. ~}j pounds, at two-thirds cent .05 



Miin and team, one hour, at 'Jn cents . :>5 



Total cost of one aiipli<"iti<)n with ti.xcd nozzles !_ __' :L .$0.95 



When trailers are used: 



Two men to carry trailers, at l.~) cents . liO 



Total cost of one ;ii)plication when trailers ;ivr used 1.25 



Cost of five applications : 



Three applications with fi.xed nozzles, at 05 cents ^__ 2. S5 



Two api)Iications with trailers, at .$1.25 2.50 



Total cost of five applications to 1 aci-e, three with fixed 



nozzles and two with trailers 5.35 



GENERAL CONCLUSION. 



In comparing the results with the dift'erent formulas for Bordeaux 

 mixture used there seems to be very little to choose. There was prac- 

 tically no difference in their fungicidal value in Mr. Giddings's 

 vineyard, Avhile in Mr. Tuttle's the percentage of difference, though 

 con.siderably greater, was not particularly striking. 



The plats sprayed with 4—3-50 Bordeaux mixture with soap added 

 gave the lowest percentage of rot, and this mixture is probably the 

 best for general use. The results with the 3-2-50 formula, however, 

 were very good, and it is possible that it is as good a fungicide as 

 any of the other mixtures. The addition of soap in the last spraying 

 onW considerably reduces the expense and seems as efficient as where 

 it is used all through the season. Soap should not be added later 

 than July 15 where the season is like that of Michigan. The use of 

 soap at later dates is liable to injure the sale of the fruit, as the 

 mixture is very adhesive, and if the latter part of the season is dry 

 it will still be on the grapes when they are picked. 



In view of the results of the work of the season of 1909 and of the 

 previous two years, the recommendations for spraying in INIichigan 

 are as follows: 



First application, when the shoots are from 8 to IG inches long, 

 using 4-3-50 Bordeaux mixture to cover the young growth before 

 it becomes infected. 



[Clr. 65] 



