COPPER SPRAYS ON IRISH POTATO TUBERS. 1% 
tatoes under them dug. The dirt was shaken from the vines and 
the adhering roots, and the soil was wiped from the tubers. The 
vines and tubers were then weighed together and separate weighings 
of the tubers were made. From these data the percentage of tubers © 
in terms of the total weight of the vines plus tubers was calculated. 
TABLE 7.—Weight of potato vines and tubers, Presque Isle, Me., 1921. 
: Bordeaux-sprayed. | Pickering-sprayed. No (Gheeky 7 ay 
ae Date : : 
Variety. weighed. | 
Vines.| Tubers. | Vines. | Tubers. |Vines.| Tubers. 
| | 
| 4 
| Lbs. | Lbs. | Perct.| Lbs. | Lbs. | Perct.| Lbs. | Lbs. | Per ct. 
¥eish Copbler:.... - ----..-==- July, 262 | 7-50))-*3.00,| 28.5.) 97.25, |=.2.50.} 25-6. |, 9.75.1 22.50 20. 4 
Tees ees Oe ee De pee Aug. 152) 5.25 )°5275.) 52:3) 7-00 | 7200 | 50°07) 5525 | 5.25 50. 0 
US Rae See ee eee Sept. 173| 3.50} 8.50] 70.8| 3.25; 9.00] 73.5] 2.50] 11.25] &81.8 
Harly*ivose: 5-25 -4 &leosb Na Pay Pd AT AGM | ry i gS Seed Per eaters 6.00} 2.75 31.4 
ES Se OE Pane Aug. 192] 6.75 | 6.75} 50.0 |.....-- Pes Cee 6.75 | 6.75; 50.0 
Vee = = ee Se eee ea Sept. 143}] 6.25 | 13.75 | 68.8 |.....-- eesti ps |e eS 4.75 | 13.00 | 673.2 
esivhy. Obi os E Rae 7S 21 Y 6507275 | QOET Eee Pisce Th OS 8.25] 2.50] 23.3 
eee eee a Aug. 182] 7.25 | 6.75} 48.2 |....... [sa5255 Bete 8.25 | 8.00 49.2 
yet SoU Seg Sept. 133] 4.25] 8.25] 66.0 |.....-- ee haere 4.00} 8.00! 66.7 
Green Mountain........--- Aug. 231] 10.75 | 4.00} 27.1-/#11.50 | #5.00 | 430.3 | 8.50 | 2.75 | 24.4 
LG eels Seen oe eee Aug. 2372] 7.00} 5.50] 44.0] 5.25] 4.00] 48.2] 5.75) 4.00 41.0 
Tee eee ae EATER 29 Ee EE Sees 28 44.25 |44.00 |} 448.5 | 5.00) 5.00 50.0 
= CLR ee Sept. 203 3.38 | 7.38 | 68.6 | 44.00 | 48.75 | 468.6 2. 25 | 7.25 | ©76.3 
He OOS Se te Septs 205). 252)| ee [ern diab P10! 50P 7.4 (LL) lee Mies 
[PS ae Pee ae domss etry) | 59.50 | 576.0 | 
1 Date of first analysis. 
2 Date of second analysis. 
3 Date of last analysis. 
¢ Barium-sprayed. 
* Nickel-sprayed. 1 
6 The check vines at time of last analyses were dead or partly dead and therefore lighter than the 
vines of the copper-sprayed plants. These figures are not comparable with the other data. 
The data presented in Table 7 show that when the potato vines 
were growing, that is, while they were green, a higher propor- 
tion of tubers to vines plus tubers was usually found in the copper- 
sprayed than in the unsprayed plants. At the time the first weigh- 
ings were made, as soon as the tubers were about an inch in diameter, 
the infiuence of the copper sprays was shown. The results in Table 
7 indicate that the stimulating effect of the copper is largely shown 
by the increased weights of tubers rather than by increased weights 
of the vines and that it is exerted early in their development. As the 
tubers are the storehouse for the starch formed in the leaves, the per- 
centage of starch in the tubers would naturally increase. At the 
time the last analyses of the tubers were made the unsprayed vines 
had partly dried and therefore were lighter than the corresponding 
vines for the copper-sprayed plants. The data for these samples are 
not directly comparable with the rest of the data. 
INFLUENCE OF STRENGTH AND NUMBER OF APPLICATIONS OF COPPER SPRAYS 
ON COMPOSITION OF TUBERS. 
Several samples of tubers grown in New Jersey during the season 
of 1920 were analyzed for solids and nitrogen. Some of the plots 
from which samples were taken had received a 10-10-50 Bordeaux 
spray; others had received a 5-5—50 Bordeaux spray; a third plot 
had been treated with a 24-24-50 spray; while some of the plots had 
received no copper spray. The results for solids and nitrogen in 
