This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
A spray may be effective (1) by hitting the enemy, (2) by placing poison before the depredator, and (3) by protecting the plant with a covering unfavorable to the growth of the pest. The cautious farmer insures his crop against injury by insect or vegetable parasites by spraying. The fruit-grower asks, "Do I need to spray this year? My trees are not blossoming." "Certainly," we answer, "spray to protect the foliage from possible injury by insect or fungous disease." Healthy foliage is essential to the protection of health and vigor and fruit-buds. Spray this year for next year's crop.
Insecticides kill by contact or by means of a poisonous principle; their efficiency depends largely on the time and thoroughness of the application. If applied too soon they may be dissipated before the insects appear; if applied late the injury is only partly prevented, because insects feed less voraciously and are harder to kill as they approach maturity in the larval stage. With the vegetable parasite, the case is not essentially different. The tree is covered with a thin coating which destroys spores of fungi resting there and prevents other spores from germinating. Fig. 1326 shows the stage of development of fruit-bud calling for bordeaux mixture and paris green. The keynote to success is thoroughness. Hasty sprinklings are worse than useless; they discourage and disappoint the beginner. Full protection is not afforded unless each leaf, twig and branch has been covered. Time is the next most important factor bearing on success. The early spray is most effective. This applies particularly to the treatment of fungous diseases. Spray before the buds open.
Get ahead of the enemy.
Bordeaux mixture was first applied with a broom (Fig. 1327). Poison distributors were first made in America for the protection of cotton, potato and tobacco. There are five general types of pumps: (1) The hand portable pump, often attached to a pail or other small reservoir, suitable for limited garden areas. (2) The knapsack pump carried on a man's back and operated by the carrier. The tank is made of copper, holds five gallons and is fitted with a neat pump which may be operated with one hand while the nozzle is directed with the other. This pump has been modified recently so that all the pumping is done when the sprayer is filled and before it is placed on the shoulders.
Fig. 1330. A garden barrel pump.
Fig. 1331. An orchard barrel pump.
Excellent for spraying small vineyards and vegetable-gardens. (3) A barrel pump; a strong force-pump fitted to a kerosene barrel or larger tank suitable for spraying young trees; may be mounted on a cart, wagon, or stone-boat, depending on the character of the ground and size of trees. (4) A gear-sprayer; being a tank provided with a pump and mounted on wheels. The pump is operated by power borrowed from the wheels as they revolve, and transferred by means of chain and sprockets. Suitable for vineyards and field crops, which may be satisfactorily covered by the spray as the machine moves along. For this reason it is not adapted to orchard work. (5) The power sprayer; power being furnished generally by gasolene, sometimes by compressed air. When the trees are large and the orchard over 5 acres in extent, a power sprayer will usually pay. Some of these various types of machinery are shown in Figs. 1328-1335. In recent years the spraying of field crops and shade trees has developed rapidly. The spray pumps have been adapted to this work by the use of special attachments. For the field crops, nozzles are distributed along a horizontal arm, which makes it possible to cover a wide strip.
The sprayers for shade trees are equipped with a more powerful pump, which is usually multiple-cylinder. The pump must be capable of delivering a large quantity of material each minute under a pressure of 200 to 300 pounds. The nozzles for this work are of the solid stream type and are usually fitted with interchangeable tips varying from 1/8- to 1/4-inch aperture. In order that the tops of high trees may be reached by the spray mixture, it is necessary to use a long extension rod, as well as very high pressure.
Fig. 1332. Square tower, giving more working space for the nozzle-men than the conical form.
Fig. 1333. A power sprayer for orchard use.
Fig. 1334. A traction power sprayer, for street and park trees.
Fig. 1335. Spraying park trees with the machine shown in Fig. 1334.
The essentials of a good pump are (1) durability: secured by having working parts made of material least susceptible to the action of the various spray solutions, friction considered; (2) strength: obtained by a good-sized cylinder, substantial valves, wall and piston; (3) easily operated: found in a pump with a long handle, large air-chamber and smoothly finished working parts. A pump should be strong enough to feed two leads of hose and throw a good spray from four nozzles. Nearly all spray mixtures require constant stirrings to prevent settling and insure uniformity, and an agitator is a necessary part of the equipment.
Much of the efficiency of a spraying machine depends upon the nozzle. It should be chosen for the particular work to be done, rather than for any special design. The development of nozzle construction has been rapid, new features being embodied as necessity demanded, until today there are four main types, each of which is intended, for specific work: (1) The Bordeaux nozzle is the oldest of the modern types. It came into general use about 1890 and was at first universally adopted for all spray work. It throws a stream which may be regulated from a solid jet to a coarse fan-shaped spray, both of which are too coarse for general use. The Bordeaux has, however, one place in the list of modern spray nozzles and that is for the codlin-moth spray. For this application it is desirable to force the material into the calyx cups of the developing fruit and no nozzle does this quite so efficiently as the Bordeaux. (2) The Vermorel was the next step in development after the Bordeaux. It was very much superior to the latter, breaking the material up into finer particles, and was generally used until about 1906. This nozzle, however, does not possess any desirable features not found in the disc types and therefore has no special uses in modern spraying. (3) The disc nozzles are standard for general spraying work.
They are represented by a large number of sorts, each made by different manufacturers, but all working on the same principle. The material is whirled inside of the nozzle before it reaches the final outlet, thus breaking it up into finely divided parts and producing the desired mist. The material is lastly passed through a disc, which may have either a large or small opening. For orchard and small crop spraying, the small opening is used, in which case the nozzle should be 3 to 7 feet from the object to be sprayed. For taller orchard trees and for small ornamental trees, the large opening is used. This produces a solid jet which breaks into finer particles at a distance from the nozzles, depending upon the pressure used. (4) Shade tree nozzles, to be used only for spraying very tall ornamental trees, and in connection with at least 300 pounds pressure. They throw a solid stream 30 or more feet in the air, at which point the material is broken into a coarse mist. This type came into use at the time of the introduction of the brown-tail and gypsy moths in the New England states, and has since been widely used for parks, estates and forest spraying. c.