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BULLETIN 1 14*;. r. s. DEPARTMENT OF AGRICULTURE. 



samples and the average solids content for the three sets was 23.92 

 per cent from the Bordeaux-sprayed plants, as compared with 21.69 

 per cent for the tubers from the check vines. The two samples of 

 the American Giant variety from New Jersey had practically the 

 same content of solids and the tubers from the Bordeaux-sprayed 

 vines had but slightly higher contents of starch and nitrogen. 



The average results for the tubers from the four States show that 

 the general effect of the copper sprays is to increase the solids 

 content of the tubers. 



1921 DATA. 



Presque Isle, Me. — The 1921 experiments were conducted at 

 Presque Isle, Me., to determine the influence of Bordeaux, Pickering, 

 and barium-water sprays, all containing copper, on the yield of 

 tubers. The data were compared with data obtained from check or 

 noncopper-sprayed plants in each case. All of the plants received an 

 arsenical spray. 



Table 6. — Yield from 3 varieties of potatoes, Presque Isle, Me., 1921. 





Front plots. 



Rear plots. 





Variety. 



Plot 

 No. 



Spray used. 



Yield.! 



Plot 

 No. 



Spray used. 



Yield.i 



Total.' 



Aroostook farm: 



Early Rose 



Early Ohio 



2 



4 



5A 



6 



8A 



9 



11A 



1A 



2A 

 3A 

 3C 

 4A 

 5A- 

 6A 

 6C 

 7A 





Pounds. 



2 128 



2 106 



868 



864 



1,020 



1,070 

 1,046 



723 



639 



583 

 671 

 732 

 664 

 648 

 744 

 625 



1 



3 



5B 



7 

 8B 



10 

 11B 



IB 



2B 

 3B 

 3D 

 4B 

 5B 

 6B 

 6D 

 7B 



Check (no copper). . . 

 do 



Pounds. 

 2 107 

 299 

 724 

 780 

 821 



850 



909 



636 



707 

 532 

 733 

 660 

 716 

 613 

 711 

 711 



Pounds. 



do .• 





Check (no copper). . 



do 



1, 592 

 1,644 



Do 





Green Moun- 

 tain. 

 Do 



Check (no copper). . 



Check (no copper). . . 



1,841 

 1,920 



Do 





do 



1,955 



Biieeland farm: 







2,751 



tain. 

 Do 



Proprietary spray. . 

 Check (no copper). . 

 Barium spray 



Proprietary spray. . . 

 Check (no copper). . . 

 Barium spray 



2,682 



Do 



2,376 



Do 



2,859 



Do... 





Do... 







2,760 



Do... 



Check (no copper). . 



Barium spray 



Proprietary spray. . 



Check (no copper). . . 



Barium spray 



Proprietary spray. . . 





Do 





Do 









1 Yield from 2 rows, 300 feet long, in case of Aroostook farm potatoes; yield from 2 rows, 225 feet long, 

 in case of Kneeland farm potatoes. 

 8 Yields from 50 hills each. 

 * Yield from 2 plots in case of Aroostook farm; yield from 4 plots in case of Kheeland farm. 



From the data from the Aroostook farm and from the Kneeland 

 farm (Table 6) it is evident that the copper-sprayed plants generally 

 gave an increased yield of tubers. In 1921 there was no late blight 

 (Phytophthora infestans) in northern Maine. The reason for using 

 copper sprays in this locality is to control this fungus. Increased 

 yields seem to follpw the application of these sprays in seasons when 

 no late blight was prevalent. 



PROPORTION OF TUBERS TO VINES PLUS TUBERS. 



The weights of vines and tubers were determined at Presque Isle, 1 

 Me., at the time the analyses of the tubers reported in Table 1 were 

 made. As a rule, eight healthy potato plants were pulled andithej 



