We are just now in the epoch of the control of insects and plant diseases by means of applications of substances. This epoch will never pass ; but in time we shall give greater emphasis to such an organi zation of the business of plant-growing as to circumvent the difficulties. We seem to have passed the epoch of mere plant doctoring,—a suggestion, no doubt, from the prevalent medi cine-habit in man—whereby we hope to kill the insect or cure the disease by putting some substance into the "circulation" of the plant ; but the day of quacks has not gone by. It would seem to be needless to say to any person that he would better get expert professional advice, when he is in diffi culty with insects or plant diseases, were it not for the fact that it is necessary to say it. Howbeit, the person to whom this needs to be said will not read this book, so that we may at once pass on to profit able matters.
Kerosene Emulsion.—Hard, soft or whale-oil soap, pound ; boiling soft water, 1 gallon ; kerosene, 2 gallons. Dissolve the soap in the water, add the kerosene and churn with a pump for 5 to 10 minutes. Dilute 4 to 10 times before applying. Use strong emulsion for all scale insects. For such insects as plant-lice, mealy-bugs, red spider, thrips, weaker preparations will prove effective.
Cabbage-worms, currant-worms, and all insects which have soft bodies, can also be successfully treated. It is advisable to make the emulsion shortly before it is used.
For San Jose scale, use 1 pound of whale-oil soap and dilute in proportion of one part to six of water. Especially effective in summer to kill the young and tender lice.
Miscible or "Soluble" Oils.—Recently various oils that emulsify readily when poured into water have been put on the market. Some persons have found them to be of great value and others report poor or indifferent results. Emulsified with twelve to fif teen times their quantity of water, they are applied to dormant trees for scale.
Distillate Spray.—In order to overcome some of the difficulties in the making and use of kerosene emulsion, California citrons growers are now using a mechanical mixture of a special distillate of petroleum and water. The mixture is prepared by a sort of churn propelled by a gasoline engine, and the same engine applies the spray. For scale insects and mites on citrons fruits.
Tobacco Water.—Prepared by placing tobacco leaves and stems in a water-tight vessel, and then covering them with hot water. Allow to stand sev
eral hours, dilute the liquor 3 to 5 times, and apply. For soft-bodied insects.
Whale-oil Soap.—On dormant trees for San Jose scale, dilute 2 pounds to 1 gallon water ; for sum mer use on scale or aphis, 1 pound to 5 to 7 gallons. Dissolve in hot water if wanted quickly.
of quicklime should be added. Repeated applications will injure most foliage, unless the lime is used. Paris green and Bordeaux mixture can be applied together with perfect safety. The action of neither is weakened, and the Paris green loses its caustic properties. Use at the rate of 4 to 12 ounces of the arsenite to 50 gallons of the mixture. It is sometimes used as strong as 1 pound to 50 gallons, but this is usually unsafe and generally unnecessary. This is the old and best known insecticide, used for potato beetle, codling-moth, canker-worm, tent-caterpillar and very many other insects.
Arsenate of Lead.—See page 44.
White Arsenic.—White arsenic, being cheaper and of more constant strength than Paris green, is becoming increasingly popular as an insecticide. It may he safely used with Bordeaux mixture, or separately if directions as to its preparation are carefully followed ; if, how ever, these are neglected, injury to foliage will result. It is unwise to use white arsenic without soda or lime. Methods numbers one and two are recommended as the least likely to cause injury.
(1) Arsenite of Soda for Bordeaux Mixture.—To a solution of 4 pounds salsoda crystals in 1 gallon of water, add 1 pound of white arsenic and boil until dissolved. Add water to replace any boiled away, so that 1 gallon of stock solution of arsenite of soda is the result. Use 1 pint of this stock solution to 50 gallons of Bordeaux.
(2) Arsenite of Lime.—(a) If used alone (not in con nection with Bordeaux) white arsenic should be prepared thus:—To a solution of 1 pound of salsoda crystals in a gallon of water, add 1 pound of white arsenic and boil until dissolved. Then add 2 pounds of fresh slaked lime and boil 20 minutes. Add water to make 2 gallons of stock solution. Use 1 quart of this stock solution to 50 gallons of water.
(6) Boil 1 pound of white arsenic in 2 gallons of water for one-half hour and use the solution while hot to slake 2 pounds of good, fresh quicklime. Add water to make 2 gallons of stock solution, and use 1 or 2 quarts of this to 50 gallons of water or Bordeaux mixture.