How To Avoid Pests
THE PESTS OF GARDEN PLANTS
The life-history of plant pests and ground vermin, with the best means of saving various crops from their ravages, are dealt with in a series of valuable leaflets issued by the Ministry of Agriculture and Fisheries. These leaflets embrace a very large number of subjects, several of which belong to the farm and the orchard and are beyond the scope of the present volume. Others are rarely met with, but concerning those which are common to the majority of gardens we offer information which will, we hope, enable readers to safeguard their crops from disaster.
When adverse weather operates injuriously on vegetation the plagues that infest garden plants usually acquire increased power in proportion to the degree of debility to which vegetation is reduced. This circumstance perfectly accords with the general law of Nature, and is full of instruction as to the means of saving plants from serious injury by vermin. The keen, dry east wind that so often jeopardises fruit crops is usually followed by visitations of fly and maggot, and in this case the cause is beyond human power or forethought. But neglect of watering and air-giving to pot plants can be avoided. Good cultivation not only insures fine specimens, but is often the means of preventing the plants from failing under the attacks of Aphis, Mealy Bug, and other enemies against which the gardener has to fight an unceasing battle.
Insects are among the frailest of living creatures and they perish at a touch. As they breathe through the pores of the skin, water alone—the promoter of life and cleanliness—is death to them; and they are still more subject to sure destruction when to the water is added an active poison, such as tobacco, or a substance that adheres to them and stops the process of breathing, such as glue, clay, sulphur, soft soap, and the numerous preparations that are specially made to annihilate insect hosts.
The various stages through which the larger insects pass place them within our power at some period of their existence. The butterfly may float beyond the reach of harm, but in the caterpillar or the chrysalis state it can be dealt with effectually. Again, we may be powerless to destroy the Chafer grubs as they feed or hibernate beneath turf, but in their perfect state as Cockchafers or Rose Chafers many may be beaten down during quiet evenings, and others can be shaken from Roses at dawn or sunset. A knowledge of the life-history of injurious insects will suggest what is to be done and the right time for doing it, so that often by simple treatment they may be destroyed.
The expense of preparing mixtures and washes may be in some degree lessened by economy of application. A drenching-board fitted on a firm frame, should be provided in every place where plant-growing is carried on to any extent. The board should slope from a resting ridge at the base. The plant in its pot may be laid on the board, with the bottom of the pot against the resting ridge, and a pail should be put to catch the liquid used as it drains from the plant after syringing. Every general washing or fumigating should be followed by another at an interval of from a week to a fortnight, because, although the first operation may kill every insect, there will be many living eggs left, and these renew the race, and very soon bring the plants into as bad a state as ever, unless consigned to a happy despatch as their parents were. In some cases it will be more economical to feed than to destroy the vermin; and, as a rule, feeding vermin does not add to their numbers, in the same or any future season, for insect life is so strangely dependent on certain conditions of temperature, &c., that if the season is not favourable to a particular kind it will be scarce, no matter how plentiful it may have been in a previous year. In the case of the Turnip Fly, feeding is frequently the cheapest and surest way of saving the crop. It is customary with Dahlia-growers, and, indeed, with the growers of florists' flowers generally, to sow Lettuces where the flowers are to be planted, for so long as Lettuces are on the spot Slugs and Snails will prefer them to other food. As the Lettuces themselves serve the purpose of traps, the Snails and Slugs congregated about them may, towards evening, be caught and destroyed.
In using a mixture for the first time, it is advisable to try it on one plant only, and that, of course, the worst in the collection affected. If the preparation is too strong, the truth will be declared by the state of the plant within twenty-four hours; thus a little caution may prevent a great loss. Another good rule is to employ the several remedies in a rather weak state until experience has been gained, for not only has the strength of the medicine to be considered, but the management of the patient before and after it is administered. It is above all things important to be thorough in the cleansing of plants, because they succumb rapidly to the attacks of insects, and should be effectually and promptly cleaned or consigned to the fire. If left in a foul state they spread the infection to all around. In the space at our command it is only possible to notice a few of the garden pests, and we begin with one of the most frequent and troublesome of plant foes.
Aphis in some form or other is the most persistent and perplexing of plant pests. The Green Fly is the enemy of the softer kinds of vegetation, and the Blue and the Black Fly are common plagues of the Peach-house and the orchard. The tender body of the Aphis is instantly affected by conditions unfavourable to its life, and it is therefore easily killed; but its marvellous power of reproduction renders its extinction impossible, for in every instance a few escape, and very soon re-establish their race. Two methods for the destruction of Aphis are in vogue. One is fumigation by tobacco, either pure or in some of the numerous preparations offered, including several popular insecticides which have nicotine as a basis. These are both clean and effective. When a houseful of plants is infested no time should be lost, and the evening is most suitable for dealing with the pests. The plants ought to be quite dry and the house closely shut. A dense cloud of smoke without flame is required. Allow the smoke to do its deadly work during the night. Early next morning syringe the plants freely, and in the course of an hour or so give air. The other remedy is to use one of the many liquids which are inimical to the life of Aphis and other insect pests. To economise the liquid it is advisable to fill a pail or tub and immerse the plants individually. Take one in the right hand and spread the fingers of the left hand over the surface of the soil to prevent an accident; then turn the plant over and plunge the foliage in the liquid, moving it up and down briskly two or three times. If this is not practicable syringe the plants, taking care to wet the leaves on both sides. On the following day syringe with pure soft water.
Rose trees may generally be cleansed of fly by means of the garden engine and pure water only, the essential point being to direct the water on the trees with some amount of force for several evenings in succession whenever the fly threatens to obtain the mastery.
Soft soap dissolved in water makes a cheap and effectual wash for exterminating all kinds of Aphis, and to these ingredients quassia may with advantage be added. One pound of soft soap will suffice for ten gallons of water, into which stir the extract obtained by boiling one pound of quassia chips in water. Pot plants can be dipped in it as already advised, or the solution may be applied by means of the syringe. On the following day the plants should be cleansed with pure soft water.
The Bean Aphis, also known as the Bean Plant Louse, or Black Dolphin (Aphis rumicis). Our illustration shows the wingless female and pupa natural size and magnified. The pupa is black with greyish white mottlings, while the female is deep greenish black in colour. This insect commonly attacks the young shoots and tops of Broad Beans. It is well to cut off the infected tops and burn them. Should the attack be repeated spray the Beans with a solution of soft soap and quassia.
The Pea Siphon-Aphis (Siphonophora pisi, Kalt).—Among the aphides peculiar to vegetables this is one of the most common.
American Blight, or Woolly Aphis, generally appears first on trees grafted on dwarfing stocks, particularly the bad forms of the Paradise Apple. Rapidly the mischief spreads, healthy trees become infested, and unless checked an orchard is speedily ruined. Andrew Murray says that in bad cases of American Blight it is sometimes necessary to root up and burn all the trees, and let the ground remain unplanted for a year or two. Fruit trees should be examined periodically for this pest, and immediately the woolly spots are detected small tainted boughs should be pruned away, and from the mainstems and large branches diseased spots can be pared off. The operation may need a bold and vigorous hand if the trees are to be saved, and it is important that every scrap should be burned. There is almost certain to be a further appearance of the Blight, which should be destroyed by one of the many remedies known to be effectual. Fir Tree Oil Insecticide has proved to be an excellent remedy. Gishurst Compound, in the proportion of eight ounces to a gallon of water, with sufficient clay added to render it adhesive, makes a capital winter paint for Apple trees. But there is no cheap remedy equal to soft soap for smothering American Blight in the crannies of the bark. The soap may be rubbed into the diseased spots, or as a wash it can be brushed into the boughs.
Our illustration shows a piece of Apple twig with the aphides and their woolly material natural size. The enlarged figures represent the winged female and the wingless larva of the Apple Blight Aphis (Schizoneura lanigera). The insect is deep purplish brown in colour, and the well-known bluish white cottony material naturally exudes from it.
The Carrot Fly (Psila rosæ, Fab.), with its larva, pupa, and perfect insect, is illustrated natural size and enlarged. The ochreous shining larvæ live upon the tap-roots of the Carrot, and by eating into them cause them to rot. In colour the body of the fly is an intensely dark greenish black, with a rusty ochreous head. The presence of the larvæ in the root is made known by the change in the colour of the leaves from green to yellow, and the attacked plants should be promptly forked out entire and burned.
It is well to dig the ground in autumn, so that the earth may be exposed to the frosts of winter and the pupæ to the attention of birds. After sowing, spray the Carrot bed with paraffin emulsion. Spray again after germination, and a third time when thinning is finished. The emulsion to be made by dissolving half a pound of soft soap in a gallon of boiling water. While still boiling, pour the liquid into two gallons of paraffin and churn thoroughly until a buttery mass results. This will keep for a long time in tins. Before use, dilute with twenty times the quantity of water—soft water if possible. This is an excellent preventive. After the work of thinning, the fly may also be kept off the plants by scattering over them ashes, sand, or earth, impregnated with paraffin. Carbolic powder and soot are both disagreeable to the insect. It has been observed that when singling the disturbance of the soil is favourable to the operations of the Carrot Fly. A copious watering when the task is ended will firm the earth round the remaining roots, and prevent the fly from easily getting down to deposit eggs.
Carrots and Parsnips are often attacked by the larva of a Carrot Moth (Depressaria cicutella), which spins webs for security while feeding, and sometimes works havoc among the foliage. A simple remedy is to shake the caterpillars from the leaves of the plants, when they can be destroyed by the use of lime.
Celery Fly.—The apparent blisters in Celery leaves are spots deficient of leaf-green, which the larva of the Celery Fly has eaten. Dusting newly-planted Celery with lime or soot may do something to prevent the fly from laying its eggs, but the most certain preventive is to boil half a pound of coal tar in one gallon of water for twenty minutes, add fifty gallons of clear water, and syringe the plants about noon once or twice from the middle to the end of June. When once the grub has made a home, it should be crushed by pinching the leaf between the finger and thumb, or the injured portions of the leaves should be cut out and burned. In doing this it must always be remembered that the leaves are as much needed by the plant as the roots, and every leaf removed tends to diminish the vigour of the plant. Our illustration shows the Celery Fly (formerly known as Tephritis onopordinis, but now called Acidia heraclei) natural size and magnified. This fly is also destructive to the leaves of Parsnips, and is named onopordinis from its habit of frequenting the Cotton Thistle (Onopordon Acanthium). The larva is white to very pale green, the fly is shining tawny. An Ichneumon Fly detects the larva of the Celery Fly in the Celery and Parsnip leaves, and lays its eggs in the body of the larva. These parasites, named Alysia apii, assist in reducing the numbers of the Celery Fly.
All Celery refuse should be destroyed by fire. Infested ground may, if suitable, be trenched, bringing the subsoil to the surface and burying the top soil containing the pupæ. Frequent rough digging and the exposure of fresh surfaces to be searched by birds will also do something to abate the number of this pest. But in bad cases it will be necessary to resort to gas-lime, which poisons the pupæ and eventually benefits the soil, although in the season immediately following its use crops may be less satisfactory than usual.
Onion Fly.—Onions are frequently attacked by the larvæ of the Onion Fly, and in some instances the entire crop is destroyed. Our illustration shows the natural size of the fly and maggot, with magnified representations of both. The fly lays six to eight eggs on an Onion plant, generally just above the ground. These eggs hatch in from five to seven days, according to the temperature, and the maggots at once burrow into the Onion. The result is soon visible in the discoloration of the leaves which turn yellow and begin to decay. Several generations of the insect, the scientific name of which is Phorbia cepetorum, appear in the course of a single season. A close ally is the Cabbage Root Fly (P. brassicæ), the destroyer of Cabbage roots.
Among the numerous methods of preventing attack and of destroying the grubs the following are worth attention:—
Where this pest proves very troublesome it may be desirable to transfer Onion growing to new ground until the infested land has been purged of the pupæ. Instead of throwing useless Onion material on the waste heap to afford the fly a home for its eggs, every scrap should be burned. As the preparation of an Onion bed approaches completion, powdered lime well mixed with soot, in the proportion of two bushels of the former to one of the latter, may be sown evenly over the surface and raked in. Sand impregnated with paraffin sown along the drills has answered as a preventive. Vaporite is a destroyer of the pupæ; this preparation has proved deadly to ground vermin generally. Earthing up the Onions was proved by Miss Ormerod's experiment to be effective. The objection to this procedure is the probability of enlarged necks which are not wanted. An emulsion, composed of one pint of paraffin, one pound of soft soap mixed with ten gallons of water, thoroughly churned by a hand syringe and sprayed over the young plants in a fine mist, is a valuable preventive. The dose may be repeated after rainfall, if necessary. The quantities named suffice for a small plot only. Soapsuds are destructive to the maggots, disagreeable to the fly, and beneficial to the young plants. The suds should be sprayed over the bed from a watering can on the first appearance of a yellow colour in the grass. As a final suggestion reference may be made to a singular fact which we do not profess to explain, viz. that transplanted Onions are very seldom touched by grub. The modern practice of raising seedlings under glass in January or February, and planting out in open beds in April, offers the advantage of a long season of growth combined with comparative immunity from attack by the Onion Fly.
Turnip Fly, or Flea, is well known to the gardener, and is the most troublesome of all the aërial pests of the farm, and one with which it is most difficult to cope, not only because of its general diffusion and numbers, but because it produces a succession of broods throughout the summer, and is therefore always in force, ready to devour the crop immediately it appears. The so-called 'Fly' is a small beetle named Haltica (Phyllotreta) nemorum, strongly made, and decidedly voracious. The larvæ are not to be feared, except that, of course, they in due time become beetles. In the perfect state this winged jumping insect makes havoc of the rising plant of Turnips, but the crop is only in danger while in the seed-leaf stage. It is in the spring and early summer chiefly that the ravages of these insects occasion perplexity, for they awaken from their winter torpor active and hungry, and have a ready appetite for almost any cruciferous plant. Hence we see the leaves of Radishes pierced by them, and all such weeds as Charlock, Cuckoo Flower, Hedge Garlic, and Water Cress serve them for food until the Turnip crops are on the move, when they will travel miles, even against the wind, to wreck the farmer's hopes. The Cabbage Flea (Haltica oleracea) in some districts is equally troublesome, if not more so. Whole Cabbages may be destroyed by this pest, and even Hops are often ruined by it.
Preventive and remedial measures that can easily be carried out in a garden may be impracticable on a farm. We propose to enumerate them briefly as they occur to us, leaving the ultimate choice of weapons to those who may unfortunately find occasion to use them.
One precaution is to insure a quick germination of the seed and strong growth of the plant in its seed-leaf stage. The cotyledons are tender and tasty, perhaps sugary from Nature's process of malting; and while the seed-leaf is assailable the Haltica makes the best of the shining hour. The seed sown should be all of one age, and the newest possible, because of the need for a quick and strong growth. When a powerful artificial is sown with the seed, the quantity of seed must be increased, as a proportion may be killed by the manure. It is important always to drill Turnip seed; broadcasting seems to invite the Fly—at all events, a drilled crop is generally safer. Before sowing, the seed may be soaked in paraffin or turpentine. Of the two the latter appears to be the more successful in keeping the insects at bay.
Rolling an infested plant disturbs and weakens the insects and stimulates the young plant.
The sprinkling of slaked lime over the seedlings is at once a safe and an efficient process, and possesses the additional advantage of being beneficial to the plant. We are aware that it does not always succeed, but we are inclined to attribute the failure to a bad quality of the lime, or a careless method of employing it. There should be enough put on to make the plants white, and they will be none the worse for the whitening. Dustings of fine ashes or soot are scarcely less effective, but salt must not be used, for it injures the plants and does not hurt the beetle. All such dustings should be done in the early morning, while the plants are wet with dew. To apply a dusting at midday, when the sun shines gaily, is to waste time, and probably many of the recorded failures might be explained if we knew at what hour and in what sort of weather the work was done. Nets and sticking boards have been tried and found effectual, and yet such things are rarely used. A board thickly covered with white paint, drawn over the plot on a still, sunny day, soon becomes a black board by the myriads of Halticas that jump at and remain attached to it, the victims of their extravagant love of light. Old sacks soaked in paraffin and drawn over the drills impart a disagreeable flavour to the leaves, and a very fine spray of paraffin distributed by a machine specially constructed for the purpose has proved effective.
Finally, this, in common with all other insects in the winged state, needs a dry air and some degree of warmth for its health and happiness. Many kinds of larvæ need moisture, but no winged insect can abide moisture long, and herein is a clue to the eradication of Turnip Fly. By the simple process of spraying the plant three or four times a day, until it is out of the seed-leaf, and the danger is over, it is possible in the garden to wash out the Haltica; and any kind of insecticide or flavouring, such as quassia, may be mingled with the water to render the plants distasteful to the insects.
The illustration on page 422 shows the Turnip Fly in its three stages, and in each case of the natural size and magnified seven diameters.
Daddy Longlegs, or Crane Fly, in its perfect form of a fly (Tipula oleracea) does no harm, but the grubs, known by the familiar name of 'leather-jackets' owing to the toughness of their skins, are terribly destructive. During late summer and autumn the female fly deposits its eggs in large numbers in turf, in garden soil and amongst garden refuse. The eggs are hatched in a fortnight or so and the dark grubs lie in the ground through the winter, inflicting their maximum, amount of injury to young crops in spring and early summer. Where song birds are scarce the Tipula is capable of utterly destroying grass and of seriously ravaging the Kitchen Garden; but cultivation, aided by the robins, thrushes, nightingales, and other birds, will keep the insect within bounds, even after a hot summer favourable to its increase. Where this pest is known to exist, an application of Vaporite at the time of preparing ground for sowing or planting will destroy many of the grubs. The regular use of the hoe is also to be recommended, for by the disturbance of the soil the enemy is exposed to the sharp eye of the robin and other feathered gardeners.
Root-knot Eelworm.—One of the worst pests that a Cucumber-grower has to deal with manifests itself by the presence of minute warts or nodosities, chiefly on the rootlets. These warts, which are caused by the action of innumerable small thread-like worms named Heterodera radicicola, range from the size of a pin's head to that of a pea, and when they are present in large numbers the total failure of the Cucumber crop is the invariable result. The eelworms are probably introduced to Cucumber-houses in infected water. Each worm is about one-seventyfifth of an inch in length and is at first coiled up inside a transparent egg. At maturity the eggs crack open, and the worms on emerging bore into the most tender rootlets, and there lay their eggs. These eggs speedily hatch inside the plant and new eelworms are produced, which traverse the rootlets in every direction.
These Heterodera are by no means peculiar to the Cucumber; they attack the roots of Tomatoes and Melons, and the roots, stems, and foliage of many other plants. Our illustration shows some very small Cucumber rootlets, natural size, with the eelworms in the eggs, and also emerging from and free of the empty eggshell (enlarged eighty diameters).
Immediately symptoms of the pest are apparent from the wilting of the foliage and stems, all infected plants should be removed and burned. The soil must also be cleared out and the interior of the house thoroughly washed with a solution of carbolic acid in water:—one part of the former to eight parts of the latter. To purify the infected soil, use a solution of carbolic acid (one part) and water (twenty parts) and saturate three times, at intervals of a fortnight. Another remedy is to mix weathered gas-lime freely with the soil. In either case the soil will be unfit for use for at least six weeks after treatment. When the house has been well cleansed, fresh compost should be used, to which the addition of lime and soot, mixed with the soil, will be beneficial.
Mealy Bug.—This plague is by no means confined to plants under glass. In the case of a lot of stove plants badly affected, the desperate course of committing the whole to the fire, and then repairing and painting the house, is often the cheapest in the end. We have known a Pine-grower compelled to destroy a houseful of plants that have been infested by the introduction of a plant from a buggy collection. Mealy Bug may be known by its mealy, floury, or cottony appearance. It has a great fancy for Grape vines. One of the best remedies is Gishurst Compound, prepared at the rate of eight ounces to a gallon of water, with clay added to give it the consistence of paint. Miscellaneous stove plants may be cleansed by washing with a brush and soft soap. Our illustration shows a group of Mealy Bugs natural size, with one insect magnified.
Red Spider is present in almost every vinery, however well managed. A moist atmosphere is a great, though not a certain preventive; but it is not possible, without injury to the vines, to keep the air of the house always so humid that the Spider is unable to obtain a lodgment. Syringing promotes a moist atmosphere, and is unfavourable to the Red Spider, which thrives best in heat and dryness. But the most decided repellent of Spider is the use of sulphur on the hot-water pipes. This may be managed by sprinkling dry sulphur on the pipes, or by making a thick solution of sulphur, clay, and water, with which the pipes should be painted. Be careful not to raise the heat at the same time, for if the pipes are hotter than the hand can bear fumes destructive to vegetation will be given off. Melons and Cucumbers may generally be kept clear of Spider by means of the syringe only; but when Melons are ripening they must be kept rather dry, and it is very difficult indeed to finish a crop without having the plants attacked by Red Spider. Gishurst Compound answers admirably to remove Spider from house plants. The mixture should consist of one and a half or two ounces to one gallon of water, and should be applied with a sponge. The scientific name of the Red Spider is Tetranychus telarius. Our illustration shows one of these destructive red mites natural size, and two individuals greatly magnified.
Scale.—A very common species, found on many kinds of stove and other plants, is the Lecanium hibernaculorum, here illustrated on a twig, natural size, and magnified. It is brown, tumid, and commonly somewhat more than hemispherical in shape. Besides this species there is the L. filicum of Ferns, the L. hemisphoericum of Dracænas, the L. rotundum of the Peach, and the common L. hesperidum, or Orange-tree Bug, which is one of the flat species, and it spreads to a great variety of plants. The Scale insect sucks the sap from plants, and in some instances the ground beneath the foliage is wet and soddened by the falling sap. Spirit of turpentine applied with a soft brush is considered to be a good remedy for Scale. It is, however, advisable (as in other remedies) to test this on a small number of plants at first. A near relative, a large brown Coccus, infests pomaceous trees, and is especially partial to the Pyracantha, which it often kills outright. The Scale of the Vine is Pulvinaria or Coccus vitis. Careful washing with soap and water, and the destruction of each separate Scale as soon as seen, can be recommended for the extirpation of this pest.
Plentiful supply of water to the roots of the plants; in fact, starvation and a dry, hot air will soon bring an attack of Thrips. Generally speaking, the best remedy is fumigation with tobacco. Or tobacco water and a solution of soft soap, together or separately, if carefully applied, speedily make an end of this troublesome pest. A special preparation may be made as follows: Take six pounds of soft soap, and dissolve in twelve gallons of water, add half a gallon of strong tobacco water, and dip the plants in the mixture. Before they become dry, dip again in pure rainwater to remove the mixture. If too large to dip, apply the mixture with the syringe, and in the course of a quarter of an hour or so syringe with pure rainwater. Our illustration shows the Thrips in the larval and winged state, natural size and greatly magnified.
Ants.—These extremely interesting insects are frequently troublesome in gardens, and in the spring of the year the small red species mars the appearance of lawns by throwing up numerous heaps of fine soil. It is easy to destroy them by dropping a mixture of Paris Green and sugar near their runs. But as Paris Green is a poison, animal life must be considered. We recommend a simple remedy which entails no danger, but it must be followed up persistently. Purchase a few common sponges, as large as a man's fist. Dissolve one pound of Demerara sugar in two quarts of warm water. Immerse the sponges, wring out nearly all the liquid, and place them near the ant runs. Twice daily throw the sponges into hot water, and repeat the process until the ants are cleared. Nests located under walls can be destroyed by boiling water.
Caterpillars cannot often be treated in a wholesale way without injury to the plant. Hence it is usual to rely on hand-picking, and, tedious as this may be, a little perseverance will accomplish wonders. We have seen a fruit garden, literally hideous with clusters of Caterpillars in spring, completely cleared by a few days' steady work, costing but a trifle, and only needing to be conducted so that in removing the vermin there should be no harm done to the crops. In the same way the Gooseberry grub should be disposed of. Precautions cannot be taken against Caterpillars, but the careful cultivator will in good time look for patches of eggs and clusters of young Caterpillars on the under sides of leaves, and will carefully nip off the leaves on which the colonies are feeding, and make an end of them. This enemy cannot be raked in rank and file, but must be taken in detail, as in guerilla warfare.
Earwigs are the dread of the florist, for they spoil his best Dahlias and Hollyhocks, and are too partial to Chrysanthemums. They are readily trapped, as they like to go up to a high, dry, dark retreat; hence a bit of dry moss in a small flower-pot, inverted on a stake, will entice them into your hands; and if you are determined to keep down Earwigs, this way is sure, though, perhaps, not easy, because it must be followed up morning and evening from the beginning of June onwards. The hollow stems of the Bean make good traps, as indeed do hollow stems of any kind, for Earwigs love to creep into close, dark shelters after their nocturnal meal; and the cultivator who has resolved that he will not be eaten up by them needs only to persevere, and he may depend on trapping every Earwig within the boundaries. Unfortunately, they use their wings freely, and so travel from the sluggard's garden to find 'fresh woods and pastures new.'
Slugs are serious plagues to the gardener, and they sometimes appear in large numbers so suddenly as to suggest the idea that the little Slugs have come down in showers. Young crops are especially liable to injury from these vermin, and it is not easy, even in well-kept gardens, to keep them down. Constant attention is necessary, particularly in wet seasons. But here, as in the case of many other kinds of vermin, means may be adopted that will accomplish the double purpose of destroying the plague and benefiting the land; for lime, salt, soot, and nitrate of soda are certain Slug-killers, and will usually pay for their employment by their enrichment of the ground. The nice point always is to employ them advantageously. It should further be borne in mind that a Slug slightly touched by lime or salt has the power of throwing it off by means of the slimy exudation with which the creature is endowed. But if again quickly assailed in a similar manner death is certain to follow. Land made ready for sowing may be pretty well cleared of Slugs by broadcasting it with salt. Unfortunately, these destroyers are only effective in fine weather. In rainy seasons, or when a crop is rising, it is necessary to resort to trapping, and many kinds of vegetable refuse make tempting baits for Slugs. Pieces of Orange peel, suitably placed, are soon covered with the vermin, especially in the winter during intervals of frost. Cabbage leaves, sliced Turnips and Potatoes, or almost any waste vegetable may be used. The traps should be scattered about at dusk, and be gathered up in the morning, and buried in pits, or destroyed by fire.
Gas-lime is highly destructive to Slugs, but when first applied it is poisonous to plant life. An excellent method of using it is to dress the surface in autumn at the rate of from four to six cwt. per acre, and to dig the ground deeply four weeks later.
Rows of Peas are easily protected by a covering of barley sweepings, or by charcoal broken very small and flavoured with paraffin. Slaked lime, carefully used, is also employed with satisfactory results.
Snails.—In their methods of attacking garden vegetation, and in the extent of damage they cause, Snails may be placed in the same category as Slugs. During the day the Snail usually remains in hiding, emerging from rockeries and creeper-covered walls in the evening or after a shower of rain. They may be trapped by one of the methods suggested for Slugs, and preference should be given to the use of Cabbage leaves. It will, however, be safer to protect young plants by giving heavy dressings of lime or soot. Hand picking is the surest means of dealing with them, and in the winter months large numbers may be collected from among box edgings, the base of ivy-covered walls and similar shelters. Birds, especially thrushes, show a marked partiality for Snails.
Wasps are a terrible scourge in some gardens. They spoil a large quantity of fruit, and jeopardise the remainder by forcing the harvest before the crops are ready for gathering. When the localities of the Wasps' nests are known, it is a simple task to dispose of them. Turpentine and gunpowder were formerly in vogue, especially among the younger members of the community, to whom a spice of danger is always an attractive element in the fun. But these are clumsy methods of destruction and will not compare with the far easier remedy of poisoning the colonies by means of cyanide of potassium. Dissolve one ounce of the drug in a quarter of a pint of water. This will be sufficient to destroy several nests, but it is a deadly poison, and must be kept in a place of safety. Soak a piece of rag in the fluid, and lay it over the entrance to the nest. There is no occasion to run away; not a Wasp will venture out, and those which return from foraging will not lose their tempers and find yours, but at each successive attempt to enter their home they will become feebler, until they fall near or beneath the drugged rag. After an hour or two the nest may be dug out, when every insect, including queen and pupæ, will be found dead.
If the colonies lie beyond your frontier, or their positions cannot be ascertained, the enemy must be disposed of by stratagem and in detail. One of the best modes of trapping them is to put some injured fruit beneath one of the trees, and over it a hand-light raised about three inches above the ground by stones or pieces of wood placed at the four corners. This light must have a rather large hole at the top. Upon it should rest another light from which egress is prevented, except through the apex of the lower light. After the Wasps have visited the fruit, they will rise into the first light, and gradually find their way through the opening into the one above, from which not one insect in a hundred will escape. In a trap of this kind we have seen an enormous number of Wasps and Hornets which had been lured to death within a few hours.
Another simple and effective method of destroying these pests is to pour a small quantity of ale mixed with sugar into glass jars and suspend them from branches of Pear or Plum trees. The vessels must be emptied every few days and the liquid renewed.
Wireworm is the most persistent and destructive of all the ground vermin. There are fully a dozen species of beetles the larvæ of which are known as 'Wireworms,' and of these the 'Spring-Jacks,' 'Click-Beetles,' and 'Blacksmiths'—Elater obscurus, E. lineatus, and E. ruficaudis—are the most prevalent. The female beetle deposits her eggs in the earth in the height of the summer, and in due time the worms emerge and commence their depredations. These worms have a tenure of three to five years in their subterranean homes, during which time they feed voraciously, and are not very particular as to what they eat. Their muscular power renders them expert in burrowing, and they are well protected by their horny jackets. When their term of feeding is completed, they descend to a considerable depth and change into the chrysalis state, from which they come forth as jumping beetles in the course of July and August, a certain proportion remaining in the ground to complete their final change in spring. Their power of destruction is then at an end. They resort to flowers, lead a merry life for a short time, and when they pass away leave plenty of eggs to continue the race of Wireworms.
For practical purposes the Wireworm may be regarded as inhabiting every kind of soil and consuming every kind of crop. The crops it is most partial to are Grass, Potatoes, Turnips, and the juicy stems of all kinds of cereals. The larvæ may be trapped by burying in the ground pieces of Potato, or better still thick slices of Beet root; the spots to be marked, and the traps examined every few days, when the Wireworms can be destroyed. Superphosphate sown along the drills with seed has saved spring-sown crops from destruction; and Vaporite, a proprietary article, has also been used with marked success. The latter gives off a gas smelling of naphthalene which kills the Wireworms. Soot is a well-known remedy, and by its use the crops are also benefited.
Woodlice are very destructive but easily caught, and they may be completely eradicated by perseverance. When a frame or pit is infested, they can be destroyed wholesale by pouring boiling water down next the brickwork or the woodwork in the middle of the day. If this procedure does not make a clearance, recourse must be had to trapping. In common with Earwigs, they love dryness, darkness, and a snug retreat; but while a mere home suffices for Earwigs, a home with food is demanded by Woodlice. Take a thumb pot, quite dry and clean. In it place a fresh-cut slice of Potato or Apple, fill up with dry moss, and turn the whole thing over on a bed in a frame or pit. Thus you have devised a Woodlouse trap, and next morning you may knock the vermin out of it into a vessel full of hot water, or adopt any other mode of killing that may be convenient. Fifty traps may be prepared in a hundred minutes; and those who are determined to get rid of Woodlice may soon make an end of them.
Rats and Mice.—Traps are efficient while they are new, and almost any reasonably good contrivance will answer for a time, but will fail at last, or at least for a season. To keep down Rats and Mice effectually there must be invented a succession of new modes of action, for these creatures—Rats especially—are so clever that they soon see through our devices, which then fail of effect. Generally speaking, two rules may be prescribed. In the first place it is imprudent to fill up their holes or stop their runs; let them have their way. If you stop them, they will make new thoroughfares, to the further injury of the foundation; and, besides, when you are acquainted with their runs, you know where to put traps and poison for the vermin. As to the best poison, there is nothing so effectual as arsenic; but it should be employed with great care, and before it is brought on the premises the question of safe storage must be considered. A fat bloater split down and well rubbed with common white arsenic will kill a score of Rats, provided only that they will eat it. Cut it into four parts, and place these in or near their runs, and cover with tiles or boards to prevent dogs and cats obtaining them. If this fails, try bread and butter dressed with oil of rhodium and phosphorus. The oil of rhodium seems to possess an irresistible attraction for these vermin. When dry food is preferred, there is nothing so good as oatmeal; and it is a golden rule to feed the Rats for a few days with pure oatmeal, and then to mix about a fourth part of arsenic with it. Several proprietary articles are offered for the destruction of Rats. Before resorting to these means of annihilating vermin it is necessary to take steps to prevent the bodies from proving a nuisance after death. A good fox-terrier will keep a large garden free from Rats and Mice.
THE FUNGUS PESTS OF CERTAIN GARDEN PLANTS
Many of our garden plants are liable to the attacks of fungi. Cures are in most instances unknown, but in some cases preventives—which are better—have been adopted with partial or entire success. Plants raised from robust stocks, grown in suitable soil and under favourable conditions, are known to be less liable to disease than seedlings from feeble parents, or those which have been rendered weakly by deficiencies in the soil or faulty cultivation. Whether weakness is hereditary, or is attributable to a bad system, the fact remains that disease generally begins with unhealthy specimens, and these form centres of contamination from which the mischief spreads. It is, therefore, important that seed from healthy stocks should be sown, and that a vigorous constitution should be developed by good cultivation.
Anbury, Club, or Finger-and-toe.—The disease known by these various names is common in the roots of cultivated cruciferous plants such as Cabbages, Kohl Rabi, Radishes, Swedes, Turnips, &c., and also in many cruciferous weeds, including Charlock and Shepherd's Purse. The cause of this disease is an extremely minute fungus, which may lie dormant in the soil for several years for want of a comfortable home, and when a cruciferous plant becomes available the fungus fastens on the fine roots, multiplies rapidly in the tissues, and produces malformation and decay. After the disease has made some progress insect agency frequently augments the mischief, so that on cutting open a large decaying root it is not unusual to find the interior packed with millipedes, weevils, wireworms, and other ground vermin.
Unlike the Potato disease, which spreads from plant to plant through the atmosphere, the fungus of Finger-and-toe infects the ground, and from the first spot attacked the disease spreads rapidly in all directions and in various ways. It may be carried by the soil adhering to implements or the boots of labourers. And each patch becomes a new centre of infection which is spread by digging or raking. Every scrap of infected soil, or of diseased fibre which may be added to the manure-heap, distributes the virus over a wider area, so that Finger-and-toe may suddenly appear in parts of the garden which have hitherto been free from this troublesome pest. A very simple experiment will prove the certainty and ease with which the spores may be introduced to fresh land. Macerate the tissue of old Finger-and-toe in water; use this on young isolated plants of Cabbage or Turnip and in a short time the plants will be infected.
The fungus which produces Finger-and-toe is known as Plasmodiophora brassicæ, and it belongs to the Myxomycetes, or ‘slime-fungi,' which, as a rule, live upon decaying vegetable material. The protoplasm of the fungus ramifies among and within the tissues of the roots of attacked plants, and eventually produces an amazing number of spores so small that more than thirty millions would be required to cover a superficial inch. A microscope of great power is necessary to reveal them to human vision.
The spores are capable of resting in a state of vitality for a long time, and can easily withstand the frosts of winter. The illustration shows at A the fungus in its protoplasmic condition, and at B its ultimate sporiferous or 'seed'-producing stage, after the protoplasm has changed to a mass of minute spores (enlarged five hundred and twenty diameters). When a spore in due course germinates, its protoplasmic contents escape through a small aperture in its wall and begin moving about of their own accord in a slow writhing manner. The movement is so much like that of the microscopic animal organism found in ponds, and called Amœba, that this tiny mass of moving protoplasm is called Myxamœba, to denote that it is an amœba-like form produced by one of the Myxomycetes. Each myxamœba is drawn out at one spot into a fine delicate tail or cilium, as at C, D, E, and is capable of a creeping motion in moisture. When quite free from the spores, transparent expansions or limbs extend from the bodies of the myxamœbæ, as at F, G, and when these organisms, after existing in the soil for a longer or shorter time, reach the roots of cruciferous plants, which they apparently enter through the root-hairs, they again assume the protoplasmic condition shown at A, and live within the cells, at the expense of the nurse-plant. Other cruciferous plants are less seriously damaged by the pest than are Turnips and Cabbages; but it is evident that if diseased Charlock is near Turnips, the latter are very likely to fall a prey to the disease. We advise the sowing of the best seeds, the eradication of cruciferous weeds, and the destruction by fire of all decaying Finger-and-toe material, for it is in this material that the spores of the disease rest ready for continuing the disease in the following season. It is also desirable that cruciferous plants should not be continuously grown in the same quarter—in other words, it would be prudent after an attack of Anbury not to repeat a cruciferous crop on the same ground, but to follow on with a crop of some other class.
Numerous experiments have shown that slaked lime can be relied on to destroy the spores of Finger-and-toe in infested land. An application of from fourteen to twenty-eight pounds per pole may suffice in the case of light soils, but fifty-six pounds per pole will not be too much on heavy land, and the dressing should be given either six or eighteen months before a Cabbage or Turnip crop is sown; the longer period is the more certain in its effect. Preference should be given to stone or rock lime over chalk lime. The former is much more powerful and efficient. It may be necessary to repeat the dressing twelve months after the first application. As regards the occurrence of Anbury in seed-beds, frequent transplantation is a very effectual mode of stopping its progress, for the little galls can be pinched off by the workman, and burned as he proceeds; and the plant, being invigorated by change of soil, will soon grow away from the affection. In transplanting Cabbages it is a good plan to discard and burn such plants as are obviously affected with Anbury. It is worthy of remark that in market-gardens this disease is by no means so prevalent as to interfere with the routine of cultivation, although the Cabbages, Broccoli, and Cauliflowers grown in these grounds are, under other circumstances, especially liable to attack. By 'other circumstances' we mean that market-gardens are generally kept under high cultivation, the land being perpetually turned and heavily manured; and these measures appear to be a preventive of Anbury, while they result in heavy crops. But on land less energetically tilled Anbury may prevail to such an extent as to interfere seriously with the order of cropping. Another very important mode of keeping down the pest consists in burning instead of burying the stumps and all other refuse of the crop that cannot be turned to account.
Confusion may be prevented if we point out that Club-root, Anbury, or Finger-and-toe—whichever name may be used—is quite distinct from an apparently similar malformation of the root which is sometimes induced by certain characteristics of soil, seed, or manure, and is in fact a case of reversion to the original wild type. Instead of a shapely, solid Turnip, the bulb is divided into a number of coarse, worthless tap-roots, caused by either poverty of the soil, careless cultivation, or a degenerated stock of seed. Those who save their own seed continuously for years are almost certain to become well acquainted with this malady. They will find a change of seed necessary, and at the same time an alteration in the routine of culture. A healthy, vigorous plant, derived from a pure seed-stock, does not easily make Finger-and-toe, but a sound root that stands for food and money.
'Grub.'—The wart-like growths formed upon the roots of Turnip and Cabbage by the little hard beetle known as the Turnip-gall Weevil, Ceutorhynchus pleurostigma, are also quite distinct from Finger-and-toe. By cutting across a malformed root of Turnip or Cabbage it is usually not difficult to determine the cause of the mischief. If it is Finger-and-toe the root will be found filled with decaying matter; in the case of Weevil attack the small legless maggots, commonly called 'Grub,' will be brought into view; and if it is merely an instance of reversion the cut root will appear to be healthy.
Potato Disease.—The fungus which causes the Potato Disease, or 'Blight' as it is sometimes called, was formerly known as Peronospora infestans; now it is recognised by scientific authorities as Phytophthora infestans. The mark of its pestilent touch on the foliage, and its destructive effect on the tubers, are unfortunately too familiar in gardens and on farms. In dry seasons its energies are restricted, but the scourge is never absent, and during wet summers the parasite may do its deadly work on such a vast scale as to cause a Potato famine. Moisture is a necessity of its existence, and in rotting haulm, decayed tubers, and damp soil the spores remain in a resting condition until they are afforded an opportunity of multiplying with the marvellous rapidity that invests the disease with its terrible power. A series of six illustrations, five of which are highly magnified, will enable the reader to follow the development of Phytophthora infestans.