acre over no spraying. At Cornell Experiment Station' one application of Bordeaux mixture, and three of Bordeaux mixture and Paris green, increased the yield 103 bushels per acre, while another' year six sprayings increased the yield 48 bushels per acre. At Vermont Experiment Station' two applications have in general proved most profitable. The (N. Y.) Geneva Experiment Station recommend, as the result of their trials to the year 1904, that spraying commence when the plants are 6 to 8 inches tall and thorough applications to be made at intervals of ten to fourteen days during the season, making five to seven applications in all.

Insecticides are materials used to destroy injurious insects. Poison is spread on the leaves to destroy leaf-eating insects, and materials that kill by contact are used against insects that suck plant-juices. For poisoning the first class there are on the market a number of preparations, which may be grouped as follows:*

1. Standard Remedies.-Scheele's Green, Paris Green, London Purple, Hellebore.

2. Commercial Substitutes.—Paragrene, Green Arsenoid, Green Arsenite, Pink Arsenoid, Laurel Green, Arsenate of Lead, Disparene.

3. Home-made Remedies.-Arsenite of Lime, Arsenite of Soda, Arsenate of Lead, Arsenite of Lead. 4. Proprietary Remedies.-Bug Death,' Black Death," Hammond's Slug Shot,' Quick Death, Knobug,

1 (N. Y.) Cornell Bul. 140, p. 402. 2 (N. Y.) Cornell Bul. 196, p. 48.

3 Vt. Bul. 106, p. 230.

From (N. Y.) Geneva Bul. 243, P. 329.

For analysis, see (N. Y.) Geneva Bul. 190, p. 289.

etc. In most of these the amounts of arsenical compounds present is small.

Contact Remedies-Standard.-Whale Oil Soap, Carbon Bisulphide, etc.

While some of the poisons in Group 4 (proprietary) have value, they are too expensive, and the work of various experiment stations shows that Paris green or arsenate of lead are cheaper and generally much more effective poisons.'

Paris green rarely occurs on the market pure. In New York the law requires that it contain 50 per cent. of arsenious oxide or white arsenic. Often some of this arsenic is soluble in water, and in such cases it is liable to burn foliage. If more than 4 per cent. of water soluble arsenic is present the sample should be condemned.

Paris green tends to sink to the bottom of the spraybarrel; hence, unless kept well stirred, the concentrated solution applied at the last may burn the foliage. It should be applied at the rate of about 1 pound per acre, in not less than 100 gallons of Bordeaux mixture. When applied dry, mix 1 pound of Paris green with 50 pounds of land plaster, flour, slaked lime, or any other dry powder.

At (N. Y.) Geneva Experiment Station, in 1904, Paris green was applied to potatoes at the rate of 3 pounds per acre in 150 gallons of water. Four applications were made during the season, and no injury to the foliage occurred. The results show that Paris green is of distinct fungicidal value, and that it in

1 Me. Bul. 68, 87, 98.

creased the yield of potatoes from 175 bushels per acre, on plats where bugs were removed by hand, to 221 bushels per acre, and that it was better applied in water than in lime water.

Lead Compounds.-Insoluble arsenate and arsenite of lead are recommended because they contain no injurious soluble arsenic, a heavy dose will do no harm, they lead all other materials in remaining in suspension, they adhere to the foliage, and they can be easily made at home and their purity insured. The articles required are sugar of lead (acetate of lead), costing 74 cents per pound, wholesale, and arsenate of soda, costing 5 cents per pound, wholesale, at present. They may be dissolved in cold water, but for quick solution hot water is better. The formula for making pound of arsenate of lead-enough for 100 gallons-is:

Pre

Dissolve 24 ounces of sugar of lead in 1 gallon of cold water, and 10 ounces of arsenate of soda in 3 quarts of water, both in wooden vessels.' When dissolved, pour together into the spraying-tank. pared in this way, it is superior to any ready prepared sample. Of the latter there are several makes, which may be used if but a small amount is required. "Swift's Arsenate of Lead" may be purchased in a white powder form or as a paste; it is easily mixed with water, but both forms settle more quickly in the spraytank than the freshly made. Disparene retails at 25 cents per pound, and is a heavy white paste which finally mixes well with water, but takes some time.

1 Cal. Bul. 151. (N. Y.) Geneva Bul. 243.

It has great adhesive power, and will not burn foliage. The Adler lead compounds are similar.

Arsenite of lead is made by dissolving separately 12 ounces of sodium arsenite and 4 pounds of sugar of lead, then pouring them into 150 gallons of water. The home-made mixture remains in suspension longer than the prepared. Pink arsenoid is arsenite of lead colored; it is no more dangerous to foliage than Paris green, and is cheap. It will remain in suspension about twice as long as Paris green.

Green arsenoid (copper arsenite) sometimes contains considerable soluble white arsenic, and is then dangerous to foliage, especially in a dry climate or time.

White arsenoid (barium arsenite) is dangerous to foliage.

Calco green and laurel green do not contain enough arsenic to render them of much value, and some samples cause serious injury to foliage.'

Paragrene is a prepared compound containing, in some cases, considerable soluble "white arsenic,” which is objectionable.

Arsenic and lime is a cheap mixture. Boil 1 pound of white arsenic, costing 7 cents per pound, with 2 pounds of lime in 2 gallons of water for forty minutes and add to 150 or 200 gallons of water. It cannot be safely applied alone, even with the addition of considerable lime, but may be used in Bordeaux mixture. The copper sulphate in the Bordeaux mixture seems to prevent the caustic action. If the lime and arsenic

fail to combine, the mixture is dangerous.

1 Vt. Report, 1899, p. 271. Cal. Bul. 151, p. 24.

Cost of Spraying and Profits Derived.-In 1903, at the farm of J. V. Salisbury & Son, Phelps, N. Y., the total expense of spraying' 14 acres five times was $55.76, the items being as follows:

504 pounds of copper sulphate, at 6 cents. $30.24

8 bushels of lime, at 35 cents

12 pounds of white arsenic, at 51⁄2 cents

55 hours' labor for man, at 171⁄2 cents 47 hours' labor for team, at 171⁄2 cents Wear of sprayer

2.80

.66

9.63

8.23

4.20

A good showing, considering that there was no blight

this year.

64 bushels per acre on 14 acres (896 bushels), worth. $448.00 Less cost of spraying

Net profit on 14 acres
Net profit per acre

55.76 $392.24

28.01

Mr. Salisbury sprayed potatoes for his neighbors at 80 cents per acre and furnished everything. In other experiments conducted in 1904 by the Geneva Experiment Station, the cost of each application was as low as 61 cents per acre, and the net profit as high as $60.00 per acre.

1 (N. Y.) Geneva Bul. 241, p. 275.