11 
The dry application of these poisons in the form of a powder, which is 
dusted over plants, is more popular as a means against the cotton 
worm in the South, where the rapidity of treatment possible by this 
method, and its cheapness, give it a value against this insect, in the 
practical treatment of which prompt and economical action are the 
essentials, This method is also feasible for any low-growing crop, 
such as potatoes, young cabbages, or other plants not to be immedi- 
ately employed as food. The third method consists in the use of 
the arsenicals in the form of poisoned baits, and is particularly avail- 
able for such insects as cutworms, wireworms, and grasshoppers in 
local invasions. 
The wet method.—Either Paris green, arsenite of copper, arsenite of 
lime, or London purple may be used at the rate of 1 pound of the 
poison to 100 to 250 gallons of water, or 1 ounce to 6 to 15 gallons. 
The stronger mixtures are for such vigorous foliage as that of the 
potato, and the greater dilutions for the more tender foliage of the 
peach or plum. An average of 1 pound to 150 gallons of water is a 
good strength for general purposes. The poison should first be made 
into a thin paste in a small quantity of water and quicklime added in 
amount equal to the poison used, to take up the free arsenic and 
remove or lessen the danger of scalding. An excess of lime will do 
nce injury. The poisons thus mixed should be strained into the spray 
tank or reservoir, care being taken that all the poison is pulverized 
and washed through the meshes of the strainer. The use of the lime 
is especially desirable in the case of the peach and plum, the foliage 
of which, particularly the former, is very tender and easily scalded. 
To the stronger foliage of the apple and most shade trees Paris green 
may be applied without danger at the strength of 1 pound to 150 gal- 
lons of water; with London purple it is always better to use the lime. 
The method of preparation of arsenate of lead has already been indi- 
cated. Lime is not needed with this arsenical. 
If it be desirable to apply a fungicide at the same time, as on the 
apple for the codling moth and the apple scab fungus, the Bordeaux 
mixture * may be used instead of water, adding the arsenical to it at 
the same rate per gallon as when water is used. The lime in this fun- 
gicide neutralizes any excess of free arsenic and makes it an excellent 
medium for the arsenical, as it removes liability of scalding the foli- 
age and permits an application of the arsenical, if necessary, eight or 
ten times as strong as it could be employed with water alone. 
The arsenicals can not be safely used with most other fungicides, 
such as the sulphate of copper, eau celeste, or iron chloride solution, 
the scalding effects of these being greatly intensified in the mixture. 
The dry method.—The following description applies to the pole- 

@ See F. B. 243, Fungicides and Their Use in Preventing Diseases of Fruits. 
127 
