Arsenical Poisons in the Orchard

by A. S. Packard


AS is well known, about fifty per cent. of the possible apple crop in the Western states is sacrificed each year to the codling moth, except in sections where orchardists combine to apply bands of straw around the trunks. But as is equally well known this is rather a troublesome remedy. At all events, in Illinois, Professor Forbes, in a bulletin lately issued from the office of the State Entomologist of Illinois, claims that the farmers of that state suffer an annual loss from the attacks of this single kind of insect of some two and three-quarters millions of dollars.

As the results of two years’ experiments in spraying the trees with a solution of Paris green, only once or twice in early spring, before the young apples had drooped upon their stems, there was a saving of about seventy-five per cent. of the apples.

The Paris green mixture consisted of three-fourths of an ounce of the powder by weight, of a strength to contain 15.4 per cent. of metallic arsenic, simply stirred up in two and a half gallons of water. The tree was thoroughly sprayed with a hand force-pump, and with the deflector spray and solid jet-hose nozzle, manufactured in Lowell, Mass. The fluid was thrown in a fine mist-like spray, applied until the leaves began to drip.

The trees were sprayed in May and early in June while the apples were still very small. It seems to be of little use to employ this remedy later in the season, when later broods of the moth appear, since the poison takes effect only in case it reaches the surface of the apple between the lobes of the calyx, and it can only reach this place when the apple is very small and stands upright on its stem, It should be added that spraying “after the apples have begun to hang downward is unquestionably dangerous,” since even heavy winds and violent rains are not sufficient to remove the poison from the fruit at this season.

At the New York Experimental station last year a certain number of trees were sprayed three times with Paris green with the result that sixty-nine per cent. of the apples were saved.

It also seems that last year about half the damage that might have been done by the Plum weevil or curculio was prevented by the use of Paris green, which should be sprayed on the trees both early in the season, while the fruit is small, as well as later.

The cost of this Paris green application, when made on a large scale, with suitable apparatus, only once or twice a year, must, says Mr. Forbes, fall below an average of ten cents a tree.

The use of solutions of Paris green or of London purple in water, applied by spraying machines such as were invented and described in the reports of the national Department of Agriculture by the U. S. Entomologist and his assistants, have effected a revolution in remedies against orchard and forest insects. We expect to see them, in careful hands, tried with equal success in shrubberies, lawns and flower gardens.