As to nozzles for spraying it may be said that there is no one pattern that is best for all purposes. For most uses in home grounds the cyclone or vermorel type (Fig. 233) will give best satisfaction. The pump manufacturers supply special nozzles for their machines.
Insecticide spraying formulas.
The two classes of insecticides are here described,—the poisons (arsenites and white hellebore) for chewing insects, as the beetles and all kinds of worms; the contact insecticides, as kerosene, oils, soap, tobacco, lime-sulfur, for plant-lice, scale, and insects in such position that the material cannot be fed to them (as maggots in the underground parts).
Paris green.—The standard insecticidal poison. This is used in varying strengths, depending on the insect to be controlled and the kind of plant treated. Mix the Paris green into a paste and then add to the water. Keep the mixture thoroughly agitated while spraying. If for use on fruit trees, add 1 lb. of quick lime for every pound of Paris green to prevent burning the foliage. For potatoes it is frequently used alone, but it is much safer to use the lime. Paris green and bordeaux mixture may be combined without lessening the value of either, and the caustic action of the arsenic is prevented. The proportion of the poison to use is given under the various insects discussed in the succeeding pages.
Arsenate of lead.—This can be applied in a stronger mixture than other arsenical poisons without injuring the foliage. It is, therefore, much used against beetles and other insects that are hard to poison, as elm-leaf beetle and canker-worm. It comes in the form of a paste and should be mixed thoroughly with a small quantity of water before placing in the sprayer, else the nozzles will clog. Arsenate of lead and bordeaux mixture can be combined without lessening the value of either. It is used in strengths varying from 4 to 10 lb. per 100 gal., depending on the kind of insect to be killed.
Arsenite of soda and arsenite of lime are sometimes used with bordeaux mixture.
White Hellebore.—For wet application, use fresh white hellebore, 4 oz.; water, 2 or 3 gal. For dry application, use hellebore, 1 lb.; flour or air-slaked lime, 5 lb. This is a white, yellowish powder made from the roots of the white hellebore plant. It loses its strength after a time and should be used fresh. It is used as a substitute for the arsenical poisons on plants or fruits soon to be eaten, as on currants and gooseberries for the currant-worm.
Tobacco.—This is a valuable insecticide and is used in several forms. As a dust it is used extensively in greenhouses for plant-lice, and in nurseries and about apple trees for the woolly aphis. Tobacco decoction is made by steeping or soaking the stems in water. It is often used as a spray against plant-lice. Tobacco in the form of extracts, punks, and powders is sold under various trade names for use in fumigating greenhouses. (See page 188.)
Kerosene emulsion.—Hard, soft, or whale-oil soap, 1/2 lb.; water, 1 gal.; kerosene, 2 gal. Dissolve the soap in hot water; remove from the fire and while still hot add the kerosene. Pump the liquid back into itself for five or ten minutes or until it becomes a creamy mass. If properly made, the oil will not separate out on cooling.
For use on dormant trees, dilute with 5 to 7 parts of water. For killing plant-lice on foliage dilute with 10 to 15 parts of water. Crude oil emulsion is made in the same way by substituting crude oil in place of kerosene. The strength of oil emulsions is frequently indicated by the percentage of oil in the diluted liquid:—