178 MASS. EXPERIMENT STATION BULLETIN 279 



Copper-lime dust*' was applied between 6 and S a. m. by means of a hand 

 duster. 



Potash fish-oil soap was used as a sticker with the Bordeaux mixtures and 

 with milk of lime at the rate of 3 or 4 pounds to 50 gallons. The sprays adhered well. 



It was evident that neither milk of lime nor Bordeaux mixture, even with 

 the addition of fish-oil soap, protected onions against thrips. All plots, includ- 

 ing the checks, were therefore sprayed with nicotine sulfate 1:1000, with fish-oil 

 soap 3 or 4 pounds in 50 gallons, as recommended by Bourne (3), often enough 

 to prevent injury by these insects. 



Sprays were applied between 6:30 and 9:30 a. m. The spraying, with the 

 exception of the applications made July 30 and August 5 in 1929, was done with 

 the power sprayer which Bourne (loc. cit.) has described. With this machine, 

 spray materials were applied at a pressure of 100 to 150 pounds. This outfit 

 was equipped with a spray boom by means of which 6 rows of onions (l3 inches 

 apart) were sprayed at one time. 



It was necessary to use another power sprayer in 1929 on the two days named 

 above. This involved carrying a hose from the sprayer through the field, and 

 on these dates onions were sprayed by hand, but at a pressure of 200 pounds. 

 This resulted in a much less uniform coverage and the expenditure of more 

 gallons of spray per acre. 



At the end of each season, onions were screened to remove those less than 

 Ij inches in diameter. The yields per acre of onions above this size which 

 were harvested from each plot each year are recorded in Tables 1, 2, and 3 for 

 the years 1929, 1930, and 1931 respectively. 



A thorough coverage of the plants, using the power sprayer described b}' 

 Bourne (loc. cit.) required approximately 250 gallons of spray per acre for each 

 application, as an average for the entire season. An acre could be sprayed wdth 

 this outfit in approximately 1^ hours. This figure represents the time spent in 

 actual spraying and also makes allowance for the necessary refilling. 



Estimates of cost of application are based on these figures. No estimates of 

 depreciation of the spray outfit or other items of overhead were included, since 

 these would vary according to the machinery used and could not be figured 

 accurately on an acreage basis. 



The cost of four applications of Bordeaux mixture 4:4:50, including labor 

 and materials, was $19.40 per acre. This included two applications in which 

 nicotine sulfate was added for the control of thrips. The cost of materials alone 

 for the Bordeaux and fish-oil soap combination was $2.85 per acre for one appli- 

 cation. The addition of nicotine sulfate increased the cost to $5.35 per acre. 



On a similar basis, the total cost of six applications of 4:4:50 Bordeaux 

 (including two in which nicotine was added) was $26.60 per acre. 



The 8:4:50 Bordeaux was applied twice (including one application with nico- 

 tine) at a total cost of $12.50 per acre. For three applications in which nicotine 

 was included once, the total cost was $17.50 per acre. The cost of materials 

 alone for Bordeaux of this strength with fish-oil soap was $4.25 per acre for each 

 application. The addition of nicotine sulfate raised this figure to $6.75 per acre. 



Milk of lime was applied six times (including two applications with nicotine) 

 at a total cost of $18.20 per acre. 



In every case, potash fish-oil soap was added to the Bordeaux mixture and 

 milk of lime to increase the adhesiveness of the spray and give more uniform 



•^ Cuarantood to contain not less than 19% nionoliydratcd copixT sulfate and not over Sl% 

 inert ingredients. 



