COPPER SPRAYS ON IRISH POTATO TUBERS. 13 
Connecticut were well infected with late blight before any Bordeaux 
spray was applied. All the plants died early; consequently, it is not 
surprising that the tubers showed no effect of the Bordeaux spray, 
probably because they were formed before the first spray was applied 
and were therefore too far advanced to derive any benefit from the 
sprays. The New Jersey results for solids were not higher for the 
tubers from the copper-sprayed than for those from the unsprayed 
plants in the case of all samples examined, although the average 
figures were higher for the tubers from the Bordeaux-sprayed plants. 
A discussion of the use of Bordeaux spray on potatoes in New Jersey 
by Lint (30) is interesting in this connection. He considers the cli- 
mate, cultivation, and fertility of the field to be important factors in 
determining to what extent Bordeaux is beneficial to the potato. <Ac- 
cording to this author, Bordeaux prolongs the life of the vines and 
affords the best control of fiea beetle, although increased yield of 
tubers does not consistently result from the application of Bordeaux 
to potato plants in New Jersey. 
It has been the writer’s experience that an occasional sample of 
tubers from a check plot will run higher in solids, starch, and nitrogen ~ 
than a sample from a Bordeaux- or other copper-sprayed plot. This 
is the exception to the rule, however, and may be due to the inclusion 
among the tubers selected for analysis of a potato or several potatoes 
that are not hard and firm. Sometimes one of the tubers in a hill is 
a little softer than the rest, probably because the food supply has 
been limited or checked in some way. In work of this kind average 
figures are undoubtedly the only criterion. 
1920 DATA. 
Arlington Experimental Farm, Va—tin the spring of 1920 experi- 
ments were carried out at Arlington Experimental Farm, using Irish 
Cobbler, Early Ohio, and Early Rose varieties of potatoes. Spald- 
ing Rose, Gold Coin, Irish Cobbler, and McCormick potatoes were 
grown in the fall. A 44-50 Bordeaux spray, a Pickering spray, a 
10-10-50 Bordeaux, and a 0-4—50 spray were used. The check plots 
and all the copper-sprayed plots received a lead arsenate spray. The 
figures reported in Table 4 are the averages for 53 sets of tubers 
separately analyzed. ; 
TABLE 4.—Yield and composition of tubers from sprayed. and unsprayed potato 
plants, Arlington Experimental Farm, Va., August and October, 1920. 
| Yield Composition of tubers. 
j from 
Variety. Treatment. 2 rows, 
each 100 | solids. | Starch. | Nit 
feet long. : tarch. itrogen. 
Early potatoes (August): Pounds. | Per cent.| Per cent. | Per cent. 
Trish Cobbler }....... A-4-5O"Bordeaw® ) 585050 ook See Oe 357 19. 91 14, 20 0.372 
IDSC see eee Check, (olcop per) Bxn.sc schoo os 321 19, 59 13. 70 . 368 
1D be ema IPICKCLING SULA Veen eine cee cece 340 20. 64 14. 50 - 383 
ines ee 10-10-50 Bordeaux. -:.............-. 341 20. 42 14. 70 . 367 
1) 3 SU See 0-4-50 spray (No copper)..-..-.....-.- 350 19. 85 13. 90 356 
a Olea ss: 4-4-50 Bordeaux... 2..2...2...0200-- 217 19.17 13. 90 412 
Oe sews Chock (noicoppen)i- cose ee 216 19. 28 13. 90 - 410 
Deere. 5225. iPickerins Spray reeeeeraee see aoe eee 211 19, 44 14. 70 . 433 
ar! ase *e0ss. 52-)4=4-50 Bordeaux - soi iel ites. oe .c 245 20.18 14, 38 . 367 
OP re Wie ce oe. Check @.0:copper) aes 2 2 228 18. 97 13. 60 -326 
ot Seiten wooo Pickering Spray sedssoee sees. eee 229 20. 86 14, 83 364 
1 Average of 2 sets. 2 Average of 4 sets. 
