THE SPRAYING OF PLANTS. PART I. THE HISTORY AND PRINCIPLES OF CHAPTER I. EARLY HISTORY OF LIQUID APPLICATIONS. MAN's power over the organisms which injure cultivated plants was never so great as it is at the present time. One by one these enemies have been carefully studied, the history of their lives determined, and their habits observed. Only by understanding them thoroughly can proper steps be taken to check their ravages in the most economical and efficient manner; yet it is within comparatively recent years that this first step was taken to obtain the mastery over them. Formerly, when a pest injured a plant, it was no uncommon practice to apply any remedies or materials that came to hand, regardless of their probable efficiency. It was not generally the weakest point of the organism that was assailed. In many cases it was not even the proper organism which was held responsible for the injury. Nevertheless many valuable discoveries came from these varied and desultory treatments, and some of the remedies most highly prized to-day were discovered merely by chance, not very many years ago. Present knowledge and methods of investigation, largely founded upon this experience, enable us to arrive at conclu sions which, from the outset, are founded upon a sound and logical basis. It is fortunate that this is the case. The number of the enemies of cultivated plants is either now more numerous than formerly, or the attacks are much more energetic. It is undoubtedly true that the maladies of cultivated plants are much more widespread. This fact is mostly due to the greater food supply, and to the greater ease with which most of the injurious forms can pass from one part of the country to another, because the cultivated areas lie so close together. If a plant is grown to any considerable extent, it is easy for its enemies to spread over the entire region in which it is cultivated. Physical barriers are almost without value in checking this spreading of disease. The ocean is only a partial exception, since such close means of communication have been established between all parts of the globe that this obstacle is now of little avail. Some diseases have not yet been able to overpass it, but as it has proved of little hindrance in so many cases, it is probable that ultimately the enemies and diseases of plants will be as widespread as are the plants upon which they flourish. Weedy plants, insects, and possibly also fungi, are frequently more destructive in a new country than in their old home. They are freed from the enemies or conditions which formerly kept them in check, and in some cases they are the cause of very serious disturbance, although originally they may not have been markedly destructive. Farmers and fruit growers cannot fence out the many forms of insects and fungi which live upon their crops and which are as anxious for a harvest as the grower is. It is a fight between the grower and the pest, and it must be admitted that the latter has generally had the best of the battle. The farmer has not been properly equipped. He has often had invisible foes to contend with, foes which he did not understand, and which he could not assail. It frequently occurred that an entire crop was ruined in a day or two, and the cause remained unseen and unknown; and even if it was visible, almost the only remedy upon which the grower could rely with certainty was mere force, first catching the pest and then destroying it. As this could be done with profit only in rare cases, it was little better than no remedy, and the general result was that the insect or the fungus obtained an ample supply of nourishment, and the grower took what was left. Indeed, this method is still followed by many cultivators, but it is not the safest, nor is it the most profitable one. The best is generally the most profitable commodity, and the poorest is the least so; and the grower of to-day has it in his power to produce the best. It rests entirely with him whether his apples shall be wormy or not, whether his trees shall retain their foliage or lose it from disease. There are few evils that affect his crops which he cannot control, in many cases almost absolutely. Only a few diseases remain which still refuse to submit to treatment, but the number is rapidly decreasing, and the time will come when these also will disclose some vulnerable point which will allow of their destruction. Foremost among the operations by means of which cultivated plants are protected from their enemies, is spraying. This consists in throwing upon plants any fluids, or semi-fluids, in the form of a fine rain or mist. It rests upon the general principle of covering the plants, or the parts of plants to be protected, with a thin but uniform layer of some material that is poisonous, caustic, or offensive to the organism which it is desired to destroy. The word "spraying," as understood in this connection, has not been in general use more than ten or fifteen years, for the operation previous to this time was practiced only to a very limited extent. It was then referred to as "syringing," from the fact that hand syringes were generally used as a means of making the applications. This term is still in common use among florists and gardeners, whose daily duty it is to throw water upon their plants either for the purpose of promoting growth, or in order to keep them free from foreign matter, such as insects or dust. It is essentially a term which, in this country, is used in connection with plants grown wholly or partially in a greenhouse or in some similar structure. Spraying, on the other hand, is a term now used by farmers and fruit-growers to designate a similar operation, but the plants treated are grown entirely out of doors, and pure water is rarely used. The operation of both syringing and spraying is, however, the same; namely, the throwing of liquids, more or less finely divided, upon plants or other objects. It is impossible to tell when plants were first syringed. It is very probable that the value of the operation was understood as soon as the cultivation of plants began to attract serious attention. The immediate causes which led to the practice were undoubtedly the same as those now existing. Foliage almost invariably looks brighter and fresher when wet, and one instinctively feels that if the appearance of a plant is improved by a certain operation, the general health of the plant is improved to an equal degree. The removal of insects or any injurious substances would have a similar effect, and all good gardeners would feel a temptation to improve their plants in this simple way. Insects and diseases have unquestionably troubled cultivators from the time plants were first grown. Remedies would naturally be sought, and it appears that these older gardeners were controlled by the same feeling which even to-day often manifests itself in connection with the taking of medicine: the worse the drug smells or tastes, the more good it is supposed to do. Early in the seventeenth century Parkinson advised the use of vinegar to prevent canker on trees, and the recommendation was supposed to rest upon a very firm foundation.1 One old record 2 giving instructions for making liquid applications of an insecticide reads as follows: "Cantharides (Cantarides) are flies which attach themselves to the branches near the upper parts of trees, especially on the ash. They may be destroyed by pouring or throwing on the tops of the trees, by means of a small pump, water in which has been boiled some rue." Ruta graveolens is probably meant. This herb has a strong, heavy, and very disagreeable odor, and a sharp, bitter taste. If such qualities make a plant a good insecticide, rue should be one of our most valuable remedies. It seems very probable that the idea of selecting materials which are offensive to the senses was uppermost in the minds of those who first had occasion to use them, for most of the earlier substances recommended are of 1 John Parkinson, "Paradisus," The Ordering of the Orchard, Chap. viii. 550. 1629: "The canker is a shrewd disease when it happeneth to a tree; for it will eate the barke round, and so kill the very heart in a little space. It must be looked into in time before it hath runne too farre; most men doe wholly cut away as much as is fretted with the canker, and then dresse it, or wet it with vinegar or cowes pisse, or cowes dung and urine, &c. untill it be destroyed, and after healed againe with your salve before appointed." 2 "La Théorie du Jardinage," 166, 1711. See also Deane, "The Newengland Farmer," 177-184. this character. A great variety of materials must have been tested again and again by various persons independently of each other. Those materials which possessed real or imaginary remedial values, or which from their very nature appeared to possess them, remained in use until something that promised better could be found. Thus it came that at the close of the eighteenth century, and early in the nineteenth, the number of things recommended against various diseases was large, and some of the compounds possessed considerable insecticidal value. The following examples may here be cited: "In the year 1763, there appeared in the papers of Marseilles a remedy for plant-lice. The applications should be made by means of a small tin syringe having a nose pierced by about one thousand holes. The instrument is filled with water in which lime has been slaked, previously mixing with the clear liquid some bad tobacco, finely powdered; this should be used at the rate of a handful to two liters of the liquid. The trees are syringed with the mixture, and although the foliage remains uninjured the pests are destroyed. But after four or five days the trees should be again syringed, using clear water." 1 "But many of the plant-lice may be destroyed by passing the leaves upon which they are found between two sponges wet with tobacco water. Ground tobacco powder spread upon the insects will kill them instantly. One may also use with it the water of slaked lime or of strong soap, soot, sage, hyssop, wormwood, and other bitter or strong-smelling herbs. Soot, lime, and soap have the disadvantage of staining the leaves, fruits, and the plants to which they are applied. Tobacco and wormwood leave small particles upon the portions treated. Other materials are often without value. Tansy, hellebore, rue, leek, bitter gourd, and long pepper have the disadvantages mentioned above. Petroleum, turpentine, and other oils are also recommended; but care must be taken in their use, since they also act upon the plants, making them sick or even killing them." 2 "First wet the trees infested with lice, then rub flowers of sulphur upon the insects and it will cause them all to burst." 8 166. 1 J. A. E. Goeze, "Geschichte einiger schädlichen Insecten." Leipzig, 1787, |
