This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Gardeners have often things of a very vexatious stamp to deal with, not the least of which is to be found in the various insects which infest our plants and trees. Wherever there are plants grown, even in the best-kept gardens, there insects will sometimes be found; and though every one wishful of being completely successful in the cultivation of either fruits, flowers, or vegetables, trys to keep them free from these pests, yet in by far too many instances it is extremely difficult to keep them under at all seasons, especially during the spring and summer months, when, if the working staff fits the requirements of the place very tightly, as it too often does, the insects have it pretty much to themselves just then. It is very trying, even to the magnanimous temper which gardeners ought to be possessed of, to have the objects of one's care to a greater or less extent marred in beauty and hurt in health by the attacks of insects. Partly, we suppose, on that account, and partly for the sake of filthy lucre, which notwithstanding is a very handy article, there are various "insecticides" manufactured and sold, having, according to the vendor's way of thinking, properties of the most destructive character to all kinds of insect-life peculiar to the inmates of our gardens.
From experience, we know some of these insecticides fulfil the promises made for them by their inventors; but to use them even on what could not be named a large scale, comes to be very expensive: and so gardeners continue in the old ways of patiently brushing and sponging off the mealy bugs and "scale " in variety, infestors of the inmates of their greenhouses and stores, destroying others with the essential poisons found in tobacco, the effects of which, on the portion of the human family which uses it, is said to be seen in a degeneracy of muscle, and other evils to which flesh is not heir to. The fumes of sulphur are called into request for the extermination of other vermin; whilst in some instances they are individually stamped out by the unaided use of the hand. Boiling water is, so far as we know, certain death to all kinds of animal life: even the Trichinae, which our Continental Teuton brethren swallowed with their pork, had to succumb to the power of this agent. Acting on this fact, some have used water sufficiently hot to destroy insect life, though harmless to the plants infested, with the greatest success.
We have had occasion to use it in a somewhat extensive manner lately for the destruction of scale and bug on stove and greenhouse plants, and so satisfactory have the results proved to us, that we cannot forbear mentioning it as an inducement to brother gardeners to try it for themselves. From experience, we knew soft soap and hot water to do its work as a plant-cleanser well and quickly; so we had no fear of the results. A change of situation in the end of last year brought us into contact with plants and fruit-trees on which the insects just now in question were pasturing in any number. The Camellias, some of large size, and planted out in the conservatory, were being sponged with cold water when we took possession. In a wonderfully short space of time they were as dirty as ever; and by the time they were flowering their best, the leaves were black with smut. Directly the flowering was over, operations were commenced by syringing them thoroughly and forcibly with soap and water, so hot that it was painful to hold the syringe with the naked hand. Most of the trees were also sponged with the same solution as hot as possible, and again syringed with it, and afterwards with cold water, leaving every leaf clean and shining.
Two of the largest we were obliged, through press of work, to let go without the sponging. Though the insects were as effectually cleared off these as off the others, the whole of the dirt could not be induced to peal off the leaves, though a good deal of it did. In June a new colony of them simultaneously took possession of the trees, and the first wet morning all hands were set to work, the same sort of reception being given to them as to their predecessors. The whole of the trees were sponged as before, and all through the summer have been very thoroughly washed with cold water, applied at a strong pressure. Only one scale has been found since. They are now, September 3, being subjected to a hot-water syringing and sponging as before, which we hope will see them into next summer without needing more. Far from the hot water harming them, they have made a strong growth, and in some cases the flower-buds will have to be thinned very considerably. The same treatment will be found equally successful to clean such plants as Ixoras, Crotons, Oranges, Stephauotis, Gardenias, Francisceas, etc.
In a case of Cucumbers, which got infested with mealy bug, by syringing weekly with soap and water at 110° to 120° we exterminated them without in the slightest degree hurting either the foliage or fruits. Through circumstances over which we had no control, the inmates of our second vinery got colonised with red-spider from one end of the house to the other. Though it appeared rather a formidable job to wash every leaf in a house over 30 feet in length, still something had to be done, and washed they were with the soft soap and water as hot as could be used. At the end of two days every leaf was free from the destructive pest without effecting the least noticeable injury. The precaution of sulphuring the pipes was also taken, and prevented the reappearance of the enemy. Occasionally filling vineries with the fumes of sulphur is a sure preventive to red-spider, if everything else in the way of precaution and good cultivation is followed; but if once the spider gains a footing, the best and quickest plan is to sponge all leaves on which the spiders are, at the same time sulphuring the pipes. It is possible to get rid of them by sulphur alone; but to effect this it must be applied at a strength that will damage the younger leaves.
Thrips are another family which are troublesome to get rid of. It is well, on the slightest appearance - even if but one is seen - to fumigate immediately, repeating it three or four times in a fortnight, filling the house slowly and as full as possible. "The Squire's Gardener" some years ago advised using the nail of the thumb to catch them as a means of keeping a winter Cucumber free from them. Acting on the hint, we have repeatedly used the point of a knife wetted with which to catch them; we got over them quicker than with the thumb-nail. Taken as a whole, Ferns are a class of plants requiring more time and care to keep clean than any other. Owing to the delicacy of their structure, such rough measures cannot be resorted to as in the case of other plants. Gymnogrammas and Nothoclcenas go scot-free from all sorts of insects. Some of the Adiantums are but slightly troubled with them, but the generality of this order of Cryptogams require constant watching to keep them clean. Where Ferns have got badly infested with scale, it is the best plan to cut them over close to the soil and let them start afresh - keeping a sharp look-out, meanwhile, that they do not again effect a footing.
That beautiful Fern Pteris tricolor is seldom seen in good condition, though it is not a difficult one to cultivate, solely because of the damage done to it by scale. The Pteris family are very subject to insects, and the only means of doing them well is to keep a constant eye to them: moving those which it is not possible to keep clean to a lower temperature makes a great difference. Lomaria gibba and its varieties suffer much from Thrip if grown in too high a temperature. Young plants of the normal variety are line for room-decoration. We find them do well in a cold frame, shaded during the summer season. Greenfly sometimes attacks Adiantums of the cuneatum section. A dusting of snuff or tobacco-powder, which is quite as effective, and much cheaper than snuff, is the best means of getting rid of these. These do not stand fumigating except when they are comparatively at rest, when a slight doze will not harm them.
We have seen much labour expended on fruit-trees to clear them of scale. The Peach and Plum trees here were in places completely covered with them: we had the affected parts painted with linseed-oil, by which they have been cleaned. In the ' Handy-Book of Fruit Culture under Glass' water at a temperature of 160° is shown to entirely rid the trees of these insects. The same means will insure the destruction of American Blight. Hot water is also destructive to ants; it may be used hot enough to kill the vermin without hurting the roots of plants. The same means may be resorted to to kill wood-lice - a vermin which is classed as the Gardener's friend in ' Our Garden Friends and Foes,' though quite erroneously. Mice sometimes get troublesome; where a cat is objected to there is nothing like poisoning them. Phosphor-paste will be found excellent for destroying all sorts of vermin as well as these. Worms often prove mischievous to the gardener; lime sprinkled on the surface either of lawns, walks, or pots, and then watered, or dissolved in the water and then applied, is equally effective. It is not safe to apply lime to all sorts of plant.
Then there are caterpillars, which devour the leaves of our Gooseberries, eat up breadths of Cabbages wholesale, or prey on the foliage of our tender plants: hand-picking, when once they are there, is as effective as any plan; but prevention to a considerable extent may be secured by keeping the ground constantly stirred amongst the bush-fruit and green crops in the winter, renewing the soil on the surface where the Gooseberries are grown, and burying that taken off deeply between the rows. Slugs may be kept down by a free use of the hoe, and keeping everything in the shape of withered leaves and decaying matter clear away from all crops and flowers. Then there are the various flies which attack Turnips, Cabbages, etc., and which may be destroyed most effectually by wetting the plants and then dredging with dry sand.
The very best way of keeping crops and plants free from insects and vermin is by high cultivation and continually watching for the first trace of the enemy, then using speedy means of extermination.
We hope that amongst the number of your readers who may favour us by reading our imperfect " paper" may be found some one who could put us on to a plan by which we could clear the kitchen-garden here of wireworm: means have been tried, but without success. We can only keep summer-planted Cauliflowers and so forth from "clubbing" by refraining from planting them at all. R. P. B.