40 Farmers’ Bulletin 1128. 
insects. While the cost of the concentrated article is high, the 
extent to which it may be diluted 
makes the spray compare favorably 
in cost with other contact sprays. 
Nicotine is extracted from refuse to- 
bacco, principally stems, by different 
commercial concerns, and is put on 
the market in several grades and 
strengths. The 40 per cent nicotine 
sulphate, containing 40 per cent of 
nicotine, is the solution principally 
used, although weaker grades of 
nicotine may be employed, provided 
care is taken that the spray be 
made so as to contain- not less 
than 0.05 or 0.06 per cent of actual 
nicotine. . 
Nicotine may be added either to 
the winter-strength lime-sulphur so- 
lution for the San Jose scale or to 
the dilute lime-sulphur solution and 
arsenate of lead spray employed in 
the control of insects and diseases of 
fruit and foliage. It may also be 
used in Bordeaux mixture and arse- 
nate of lead spray without interfering 
with its effectiveness or in an arse- 
nate of lead, milk of lime, and water 
spray. In orchard spraying the 40 
per cent nicotine sulphate is used at 
the rate of about three-fourths of a 
pint to 100 gallons of water, lime-s~! 
phur solution, or Bordeau\ muix- 
ture. When used in water i.e ad- 
dition of soap at the rate of 4 
or 5 pounds to 100 gallons adds 
much to its spreading power and 
efficiency. Soap should not be used 
with lime-sulphur solution, but may 
be used in Bordeaux mixture. Where 
only a small quantity of spray is 
required the nicotine sulphate may 
be used at the rate of 1 teaspoonful 
Fic. 32.—A colony of the black peach aphis to a gallon, or 1 ounce to 8 gallons 
on peach twig heavily infested by a species oa water. 
of parasitic four-winged fly. Enlarged. of s itt 
>] 
