Brave Rose, alas, whose art thou? In thy chair
    Where thou didst lately so triumph and shine
A worm doth sit, whose many feet and hair
    Are the more foul the more thou art divine.
This, this hath done it; this did bite the root
    And bottom of the leaves, which, when the wind
Did once perceive, it blew them under foot,
    Where rude, unhallow’d steps do crush and grind
        Their beauteous glories. Only shreds of thee,
        And those all bitten, in thy chair I see.
Herbert.

 

The diseases to which the Rose is liable are generally owing either to the presence of various Cryptogamic plants, or to the attacks of certain insects whose larv? are supported at the expense of the plant. Among Cryptogamic parasites which have been observed upon rose-bushes, and which infest chiefly the Provence and other rough-leaved roses, the following are the most troublesome:

Rust.—The rust, when examined by a magnifier, is found to consist of minute yellow spots, each of which is a fungus, Lecythea Ros?. It is common and injurious to roses, as it frequently covers all the leaves. The most effectual mode of preventing its spreading is to cut off with care and burn all the infected branches, which will sometimes render necessary the destruction of the whole plant.

Mildew.—The minute fungus which produces mildew is called by botanists Sph?rotheca pannosa. It appears like a gray mould on the smaller stems and blistered leaves. It is a very troublesome enemy to the Rose, and will sometimes put at defiance every application for its destruction.[Pg 141] The most effectual is smoking with sulphur, dusting with dry flowers of sulphur, or syringing with sulphur water. The former should only be practiced by a skillful hand, as too much sulphur-smoke will sometimes entirely kill the plant.

Mould is due to a minute gray fungus, Peronospora sparsa, and manifests its presence by the appearance of irregular pale brownish spots upon the upper surface of the leaf. Upon the under surface of these spots the mould will be found.

Other species of fungi attack the Rose, but they are not sufficiently troublesome to the cultivator to need enumeration here.

The insects which infest the Rose are quite numerous, and their attacks are more or less injurious. The majority of those which are found on the plant in the state of perfect insects are comparatively harmless. The most injurious are those whose larv? feed on the leaves and pith of the trunk and limbs, and thus destroy the plant; while the perfect insect, like the Green-fly, will simply stop the growth and impair the health of the tree, by fastening upon the green and tender bark of the young shoots, and devouring the sap. It is highly desirable that amateur cultivators should devote more time to the study of Entomology, for upon an intimate acquaintance with the habits of these minute depredators depends, in a greater degree than is generally supposed, the success of cultivation. Our own leisure is so limited, that we have been able to devote very little time to this subject; and we can find no work that treats in detail the insects that attack the Rose. We simply give some account of the most troublesome ones drawn mainly from Harris’ Insects Injurious to Vegetation.

Green-Fly, or Plant-Louse.—Aphis Ros?.—This very common insect is a scourge to roses, from the facility of its[Pg 142] reproduction, and its numerous progeny sometimes entirely cover the leaves, the young sprouts, and the flower buds. Devouring the sap, they are very injurious, and, when numerous, sometimes destroy the plant, while they soil every part on which they collect. The most common species is of a pale green, but there is a variety of a dingy yellow. Many are destroyed by small birds, but they have other enemies, as the larv? of the Coccinellas, or Lady-birds, and other insects destroy large numbers. The first eggs of the Green-fly are deposited in the autumn, at the base of the buds, and are hatched in the early part of the following spring. Generation after generation is then rapidly produced, numbering sometimes eight or ten before autumn. These are produced alive, and without the intervention of the male. Reaumur estimated that a single Aphis might produce six thousand millions in one summer. The first hatching can be prevented by washing the plant with soft soap and water, or with whale-oil soap, before the buds commence swelling. When the plant is infested with them, it can be washed with tobacco-water and then rinsed in clean water. If in a house, fumigation with tobacco is better. An English writer recommends washing in a decoction of an ounce of quassia to a quart of water, as a very effective and safe remedy. Fumigation is, however, the must thoroughly searching remedy, and can be easily applied to plants in the open air, by means of an empty barrel inverted over the plant, and a pan of burning tobacco.

Gall-Flies.—Several species of Cynips, or Gall-flies, attack the rose, their punctures, made for the purpose of depositing their eggs, being followed by variously formed excrescences containing the larv?. The Bédéguars, formed by the puncture of the Cynips Ros?, were formerly employed in medicine as astringents. Harris enumerates the American species as follows:

Cynips bicolor.—“Round, prickly galls, of a reddish[Pg 143] color, and rather larger than a pea, may often be seen on rose-bushes. Each of them contains a single grub, and this in due time turns to a gall-fly. Its head and thorax are black, and rough with numerous little pits; its hind-body is polished, and, with the legs, of a brownish-red color. It is a large insect compared with the size of its gall, measuring nearly one-fifth of an inch in length, while the diameter of its gall, not including the prickles, rarely exceeds three-tenths of an inch.”

Cynips dichlocerus, “or the gall-fly with two-colored antenn?, is of a brownish-red or cinnamon color, with four little longitudinal grooves on the top of the thorax, the lower part of the antenn? red, and the remainder black. It varies in being darker sometimes, and measures from one-eighth to three-sixteenths of an inch in length. Great numbers of these gall-flies are bred in the irregular woody galls, or long excrescences, of the stems of rose-bushes.”

Cynips semipiceus.—“The small roots of rose-bushes, and of other plants of the same family, sometimes produce rounded, warty, and woody knobs, inhabited by numerous gall-insects, which, in coming out, pierce them with small holes on all sides. The winged insects closely resemble the dark varieties of the preceding species in color, and in the little furrows on the thorax; but their legs are rather paler, and they do not measure more than one-tenth of an inch in length.”

Rose-Slug, Selandria Ros?, of Harris, who gives the following account: “The saw-fly of the rose, which, as it does not seem to have been described before, may be called Selandria Ros?, from its favorite plant, so nearly resembles the slug-worm saw-fly as not to be distinguished therefrom except by a practiced observer. It is also very much like Selandria barda, Vitis, and pygm?a, but has not the red thorax of these three closely allied species. It is of a deep and shining black color. The first two[Pg 144] pairs of legs are brownish-gray or dirty white, except the thighs, which are almost entirely black. The hind legs are black, with whitish knees. The wings are smoky, and transparent, with dark brown veins, and a brown spot near the middle of the edge of the first pair. The body of the male is a little more than three-twentieths of an inch long, that of the female one-fifth of an inch or more, and the wings expand nearly or quite two-fifths of an inch. These saw-flies come out of the ground at various times between the twentieth of May and the middle of June, during which period they pair and lay their eggs. The females do not fly much, and may be seen, during most of the day, resting on the leaves; and, when touched, they draw up their legs, and fall to the ground. The males are more active, fly from one rose-bush to another, and hover around their sluggish partners. The latter, when about to lay their eggs, turn a little on one side, unsheathe their saws, and thrust them obliquely into the skin of the leaf, depositing in each incision thus made, a single egg. The young begin to hatch in ten days or a fortnight after the eggs are laid. They may sometimes be found on the leaves as early as the first of June, but do not usually appear in considerable numbers until the twentieth of the same month. How long they are in coming to maturity, I have not particularly observed; but the period of their existence in the caterpillar state probably does not exceed three weeks. They somewhat resemble the young of the saw-fly in form, but are not quite so convex. They have a small, round, yellowish head, with a black dot on each side of it, and are provided with twenty-two short legs. The body is green above, paler at the sides, and yellowish beneath; and it is soft, and almost transparent like jelly. The skin of the back is transversely wrinkled, and covered with minute elevated points; and there are two small, triple-pointed warts on the edge of the first ring, immediately behind the head. These gelatinous and sluggish[Pg 145] creatures eat the upper surface of the leaf in large irregular patches, leaving the veins and the skin beneath untouched; and they are sometimes so thick that not a leaf on the bushes is spared by them, and the whole foliage looks as if it had been scorched by fire, and drops off soon afterward. They cast their skins several times, leaving them extended and fastened on the leaves; after the last moulting they lose their semi-transparent and greenish color, and acquire an opaque yellowish hue. They then leave the rose-bushes, some of them slowly creeping down the stem, and others rolling up and dropping off, especially when the bushes are shaken by the wind. Having reached the ground, they burrow to the depth of an inch or more in the earth, where each one makes for itself a small oval cell, of grains of earth, cemented with a little gummy silk. Having finished their transformations, and turned to flies, within their cells, they come out of the ground early in August, and lay their eggs for a second brood of young. These, in turn, perform their appointed work of destruction in the autumn; they then go into the ground, make their earthy cells, remain therein throughout the winter, and appear in the winged form, in the following spring and summer.

“During several years past, these pernicious vermin have infested the rose-bushes in the vicinity of Boston, and have proved so injurious to them, as to have excited the attention of the Massachusetts Horticultural Society, by whom a premium of one hundred dollars for the most successful mode of destroying these insects was offered in the summer of 1840. About ten years ago, I observed them in gardens in Cambridge, and then made myself acquainted with their transformations. At that time they had not reached Milton, my former place of residence, and have appeared in that place only within two or three years. They now seem to be gradually extending in all directions, and an effectual method for preserving our[Pg 146] roses from their attacks has become very desirable to all persons who set any value on this beautiful ornament of our gardens and shrubberies. Showering or syringing the bushes with a liquor, made by mixing with water the juice expressed from tobacco by tobacconists, has been recommended; but some caution is necessary in making this mixture of a proper strength, for if too strong, it is injurious to plants; and the experiment does not seem, as yet, to have been conducted with sufficient care to insure safety and success. Dusting lime over the............