16 Farmers’ Bulletin 1282. 
Extensive experiments showed that a dust containing less than 
4 per cent of commercial nicotine-sulphate solution did not secure 
an efficient killing, and also that the slight increase in the percentage 
killed with strengths above 6 per cent did not justify the increased 
cost of the extra nicotine sulphate. It was determined that for 
ordinary commercial purposes, a 5 per cent strength was most satis- 
factory, considering both the killing obtained and the cost per 
pound. : 
The following figures, showing the cost of dusting, were furnished 
by a cabbage grower, who successfully checked an infestation of this 
aphis in his fields, using the hand dusters described: 
On cabbage less than half grown: 
Dust, SO Mounds Atel ar Cents seeesses = she = keene *_ $4.50 
Labor at to.25: PCr Gay 222. eee a Se eee eae 1. 65 
Total, cost: pervacret a=.” eee 2 Re eae 6.15 
On cabbage over half grown: 
Dust, s0;pounds; ats b cent sae os eee 7. 50 
Labor «at $3.25: Der daya— =e ee ee 1, 85 
meee Seg Hos 
With a one-horse duster it is possible to cover a little over an acre 
of infested cabbages an hour, applying any desired amount of dust 
up to about 60 pounds per acre. While this machine is more waste- 
ful of material than the hand dusters, its greater speed considerably 
reduces the cost of application, as shown by the following: 
Total’ Coste per-accres=—— > saa!) a p: 
S00;poundssdusteati) centsl. == sae es eee $45. 00 
One: man Jand*thorse;perdsay = eee 5. 00 
Total. cost for 10O°acres 22-24 (se ee ee ee eee 50. 00 
Total’cost- per acress 22k s _ Sa i Ae es ee 5. 00 
This gives a cost of $5 per acre, as compared with $6.15 with the 
hand machines. 
THE PEA APHIS.° 
The pea aphis is well distributed over nearly the entire country, 
and under favorable conditions multiples with great rapidity, caus- 
ing severe losses to the pea crop. This happens far too often to suit 
the pea grower, who, in order to prevent this loss, must adopt con- 
trol measures. .In many localities the growing of peas has been 
largely abandoned because of the regular appearance of this pest. 
All forms of peas and sweet peas, as well as other legumes, are sub- 
ject to attack. 
®'The price of nicotine dust has been high, but, due partly to adjustment of economic 
conditions and particularly to greater competition in its manufacture and sale, this price 
will undoubtedly be lowered somewhat another season. Labor prices may also be lower. 
Therefore, in figuring the cost of dusting the local price of both labor and dust must be 
considercd, as they will probably differ from those given in this bulletin. 
8 (Maerosiphum) Illinoia pisi Kalt. 
