16 BULLETIN 1146, U. S. DEPARTMENT OF AGRICULTURE. 
samples and the average solids content for the three sets was 93.92 
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. WIRE fe 80 wae ete ie Rk (ar eg ee ETS 
Flot | spray used rield.a | Flot Spray used Yield 
| 
- } | 
Aroostook farm: Pounds | Pounds Pounds. 
Early Rose..... 2 | Bordeaux..-.-....- 2128 1 | Check (no copper)... 2107 |=255.- 
Early Ohio..... 7 = ee deascr) Gs5 me 2106 Seeks d022. Ase 2\995}5-6- 238 
Trish Cobbler...| 5A | Check (no copper)... 868 | 5B-|..<.- it eee eee eee: 724 1,592 
13 3 as eee 6 | Bordeaux.......... 864 7 | Pickering -.....-....| 780 1,644 
en Moun- | 8A | Check (nocopper).-| 1,020} 8B | Check (mocopper)... 821 1,841 
in. 
Doss4- =: 9 | Bordeaux......-... 1,070 tO 3} Baran: . 53s). Sse 850 1, 920 
Dos 11A | Pickering.........- 1,046 | 11B |....- do ee eee 909 1,955 
Kneeland farm: 
Ggeen Moun-| 1A | Bordeaux.......... 7234. 1B), Bordeaux 52-7 355. 636 2,751 
ain. 
DOs sss. 2A | Proprietary spray-.- 63 2B | Proprietary spray... 707 2, 682 
DOs se ee 3A | Check (no copper).. 583 | 3B | Check (no copper)... 532 2,376 
Dore Ss 3C | Barium spray....-- 671 | 3D {| Bariumspray...-..-- 733 | 2,859 
Dine ae 4A | Bordeaux.-........ 732.| -4B | Bordeaux -:_......:- 660 |.--..--.- 
Doo 2 FACT Pickerme 2225 _s oe 664 | 5B | Pickering........... 716 | 2,760 
Bey = 27 sae 6A | Check (no copper)... 648 | 6B | Check (no copper)... G13,|- etic 
1 DY ees 6C | Barium spray..-.-- 744 | 6D | Barium spray-....... Tih ie eee 
Wot. eee! 7A | Proprietary spray. - 625 | 7B | Proprietary spray-..! TEISK CE Ste 
i 
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. 
2 Yields from 50 hills each. 
8 Yield from 2 plots in case of Aroostook farm; yield from 4 plots in case of Kneeland 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 follow 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) 
Me., at the time the analyses of the tubers reported in Table 1 were 
made. As a rule, eight healthy potato plants were pulled and the} 
Ne ee ee a ee ee ee ee ee ee | 
a Aa eo ee er oe hee 
. 
; 
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