44 
Colorado Experiment Station 
4. Arsenate oe Lead 
Arsenate of lead (paste) .3 to 6 pounds 
Water .100 gallons 
It is better to purchase arsenate of lead than to attempt to make it. 
This is the standard spray for codling moth and other biting insects. 
It has replaced the other arsenicals in practically all cases. 
This poison is so completely insoluble in water that it can be used 
in most any strength without injury to foliage or fruit. The fineness 
of the particles causes it to settle very slowly, and consequently it can 
be more evenly distributed than most arsenical compounds. In adhe¬ 
siveness it is superior to other arsenicalsi, but has the fault of not killing 
as qiiirkly as Paris green. 
Arsenate of lead is sold in both the form of a paste and as a pow¬ 
der. Under the National Insecticide Law, the paste must not contain 
more than 50% water and must contain arsenic equivalent to 123^% 
arsenic trioxid (AS^Os). The water soluble arsenic must not exceed 
the equivalent of three-fourths of one percent of arsenic. 
The paste has been more generally used than the powder, but if 
the powder is fine enough to remain in suspension when mixed with 
water, the results will be as good. One pound of powdered arsenate 
of lead is equivalent to two pounds of the paste form. 
In preparing both the paste and powder forms for the spray tank, 
mix them first into a very thin paste. Never throw* them as a mass 
into the spray tank. 
5 . Zinc Arsenic 
This is an arsenical compound that is comparatively new as an in¬ 
secticide. It is being quite extensively used on the Pacific coast as a 
substitute for arsenate of lead. This is a light fluffy powder containing 
arsenic equivalent to 40 percent arsenic trioxid. It goes into suspen¬ 
sion in water very readily and remains in supension better than arsen¬ 
ate of lead or Paris green. In IQ 12 , severe burning resulted in many 
apple orchards on the Western Slope where it was being tried out by 
the growers. One pound is equivalent to three pounds of arsenate of 
lead. 
6 . Bordeaux Mixture and the Arsenites 
Bordeaux mixture has been a standard fungicide for many yearq, 
and besides the fungicidal properties, it acts as a repellant to certain 
insects, especially the flea-beetles. It has also been demonstrated that 
it has the effect of lessening the burninp- effect of Paris gr-en, ars-nite 
of zinc and other arsenicals. without in]urine their poisoning qualities. 
Such a mixture will destroy both insects and fungi at one application. 
A standard formula for Bordeaux mixture is: 
Bluestone (copper sulphate). 4 pounds 
T,ime (unslacked) . 5 ponr-ls 
Water . 5 gallons 
