PROTECTING PLANTS FROM THINGS THAT PREY ON THEM Plants are preyed on by insects and fungi; and they are subject to various kinds of disease that, for the most part, are not yet understood. They are often injured also by mice and rabbits (p. 144), by moles, dogs, cats, and chickens; and fruit is eaten by birds. Moles may be troublesome on sandy land; they heave the ground by their burrowing and may often be killed by stamping when the burrow is being raised; there are mole traps that are more or less successful. Dogs and cats work injury mostly by walking across newly made gardens or lying in them. These animals, as well as chickens, should be kept within their proper place (p. 160); or if they roam at will, the garden must be inclosed in a tight wire fence or the beds protected by brush laid closely over them. The insects and diseases that attack garden plants are legion; and yet, for the most part, they are not very difficult to combat if one is timely and thorough in his operations. These difficulties may be divided into three great categories: the injuries wrought by insects; the injuries of parasitic fungi; the various types of so-called constitutional diseases, some of which are caused by germs or bacteria, and many of which have not yet been worked out by investigators. The diseases caused by parasitic fungi are usually distinguished by distinct marks, spots or blisters on the leaves or stems, and the gradual weakening or death of the part; and, in many cases, the leaves drop bodily. For the most part, these spots on the leaves or stems sooner or later exhibit a mildew-like or rusty appearance, due to the development of the spores or fruiting bodies. Fig. 211 illustrates the ravages of one of the parasitic fungi, the shot-hole fungus of the plum. Each spot probably represents a distinct attack of the fungus, and in this particular disease these injured parts of tissue are liable to fall out, leaving holes in the leaf. Plum leaves that are attacked early in the season by this disease usually drop prematurely; but sometimes the leaves persist, being riddled by holes at the close of the season. Fig. 212 is the rust of the hollyhock. In this case the pustules of the fungus are very definite on the under side of the leaf. The blisters of leaf-curl are shown in Fig. 213. The ragged work of apple scab fungus is shown in Fig. 214. The constitutional and bacterial diseases usually affect the whole plant, or at least large portions of it; and the seat of attack is commonly not so much in the individual leaves as in the stems, the sources of food supply being thereby cut off from the foliage. The symptoms of this class of diseases are general weakening of plant when the disease affects the plant as a whole or when it attacks large branches; or sometimes the leaves shrivel and die about the edges or in large irregular discolored spots, but without the distinct pustular marks of the parasitic fungi. There is a general tendency for the foliage on plants affected with such diseases to shrivel and to hang on the stem for a time. One of the best illustrations of this type of disease is the pear- blight. Sometimes the plant gives rise to abnormal growths, as in the "willow shoots" of peaches affected with yellows (Fig. 215). Another class of diseases are the root-galls. They are of various kinds. The root-gall of raspberries, crown-gall of peaches, apples, and other trees, is the most popularly recognized of this class of troubles (Fig. 216). It has long been known as a disease of nursery stock. Many states have laws against the sale of trees showing this disease. Its cause was unknown, until in 1907 Smith and Townsend, of the Bureau of Plant Industry, United States Department of Agriculture, undertook an investigation. They proved that it is a bacterial disease (caused by Bacterium tumefaciens); but just how the bacteria gain entrance to the root is not known. The same bacterium may cause galls on the stems of other plants, as, for example, on certain of the daisies. The "hairy-root" of apples, and certain galls that often appear on the limbs of large apple- trees, are also known to be caused by this same bacterium. The disease seems to be most serious and destructive on the raspberry, particularly the Cuthbert variety. The best thing to be done when the raspberry patch becomes infested is to root out the plants and destroy them, planting a new patch with clean stock on land that has not grown berries for some time. Notwithstanding the laws that have been made against the distribution of root-gall from nurseries, the evidence seems to show that it is not a serious disease of apples or peaches, at least not in the northeastern United States. It is not determined how far it may injure such trees. Of obvious insect injuries, there are two general types, those wrought by insects that bite or chew their food, as the ordinary beetles and worms, and those wrought by insects that puncture the surface of the plant and derive their food by sucking the juices, as scale-insects and plant-lice. The canker-worm (Fig. 217) is a notable example of the former class; and many of these insects may be dispatched by the application of poison to the parts that they eat. It is apparent, however, that insects which suck the juice of the plant are not poisoned by any liquid that may be applied to the surface. They may be killed by various materials that act upon them externally, as the soap washes, miscible oils, kerosene emulsions, lime-and-sulfur sprays, and the like. There has been much activity in recent years in the identification and study of insects, fungi, and microorganisms that injure plants; and great numbers of bulletins and monographs have been published; and yet the gardener who has tried assiduously to follow these investigations is likely to go to his garden any morning and find troubles that he cannot identify and which perhaps even an investigator himself might not understand. It is important, therefore, that the gardener inform himself not only on particular kinds of insects and diseases, but that he develop a resourcefulness of his own. He should be able to do something, even if he does not know a complete remedy or specific. Some of the procedure, preventive and remedial, that needs always to be considered, is as follows: Keep the place clean, and free from infection. Next to keeping the plants vigorous and strong, this is the first and best means of averting trouble from insects and fungi. Rubbish and all places in which the insects can hibernate and the fungi can propagate should be done away with. All fallen leaves from plants that have been attacked by fungi should be raked up and burned, and in the fall all diseased wood should be cut out and destroyed. It is important that diseased plants are not thrown on the manure heap, to be distributed through the garden the following season. Practice a rotation or alternation of crops (p. 114). Some of the diseases remain in the soil and attack the plant year after year. Whenever any crop shows signs of root disease, or soil disease, it is particularly important that another crop be grown on the place. See that the disease or insect is not bred on weeds or other plants that are botanically related to the crop you grow. If the wild mallow, or plant known to children as "cheeses" (Malva rotundifolia), is destroyed, there will be much less difficulty with hollyhock rust. Do not let the cabbage club-root disease breed on wild turnips and other mustards, or black-knot on plum sprouts and wild cherries, or tent- caterpillars on wild cherries and other trees. Always be ready to resort to hand-picking. We have grown so accustomed to killing insects by other means that we have almost forgotten that hand-picking is often the surest and sometimes even the most expeditious means of checking an invasion in a home garden. Many insects can be jarred off early in the morning. Egg-masses on leaves and stems may be removed. Cutworms may be dug out. Diseased leaves may be picked off and burned; this will do much to combat the hollyhock rust, aster rust, and other infections. Keep close watch on the plants, and be prepared to strike quickly. It should be a matter of pride to a gardener to have in his workhouse a supply of the common insecticides and fungicides (Paris green or arsenate of lead, some of the tobacco preparations, white hellebore, whale-oil soap, bordeaux mixture, flowers of sulfur, carbonate of Copper for solution in ammonia), and also a good hand syringe (Fig. 218), a knapsack pump (Figs. 219, 220), a bucket pump (Figs. 221, 222), a hand bellows or powder gun, perhaps a barrow outfit (Figs. 223, 224, 225), and if the plantation is large enough, some kind of a force pump (Figs. 226, 227, 228). If one is always ready, there is little danger from any insect or disease that is controllable by spraying. Screens and covers. There are various ways of keeping insects away from plants. One of the best is to cover the plants with fine mosquito-netting or to grow them in hand-frames, or to use a wire-covered box like that shown in Fig. 229. In growing plants under such covers, care must be taken that the plants are not kept too close or confined; and in cases in which the insects hibernate in the soil, these boxes, by keeping the soil warm, may cause the insects to hatch all the sooner. In most cases, however, these covers are very efficient, especially for keeping the striped bugs off young plants of melons and cucumbers. Cut-worms may be kept away from plants by placing sheets of tin or of heavy glazed paper about the stem of the plant, as shown in Fig. 230. Climbing cut-worms are kept off young trees by the means shown in Fig. 231. Or a roll of cotton may be placed about the trunk of the tree, a string being tied on the lower edge of the roll and the upper edge of the cotton turned down like the top of a boot; the insects cannot crawl over this obstruction (p. 203). The maggots that attack the roots of cabbages and cauliflowers may be kept from the plant by pieces of tarred paper, which are placed close about the stem upon the surface of the ground. Fig. 232 illustrates a hexagon of paper, and also shows a tool used for cutting it. This means of preventing the attacks of the cabbage maggot is described in detail by the late Professor Goff (for another method of controlling cabbage maggot see p. 201): "The cards are cut in a hexagonal form, in order better to economize the material, and a thinner grade of tarred paper than the ordinary roofing felt is used, as it is not only cheaper, but being more flexible, the cards made from it are more readily placed about the plant without being torn. The blade of the tool, which should be made by an expert blacksmith, is formed from a band of steel, bent in the form of a half hexagon, and then taking an acute angle, reaches nearly to the center, as shown in Fig. 232. The part making the star-shaped cut is formed from a separate piece of steel, so attached to the handle as to make a close joint with the blade. The latter is beveled from the outside all round, so that by removing the part making the star-shaped cut, the edge may be ground on a grindstone. It is important that the angles in the blade be made perfect, and that its outline represents an exact half hexagon. To use the tool, place the tarred paper on the end of a section of a log or piece of timber and first cut the lower edge into notches, as indicated at a, Fig. 232, using only one angle of the tool. Then commence at the left side and place the blade as indicated by the dotted lines, and strike at the end of the handle with a light mallet, and a complete card is made. Continue in this manner across the paper. The first cut of every alternate course will make an imperfect card, and the last cut in any course may be imperfect, but the other cuts will make perfect cards if the tool is correctly made, and properly used. The cards should be placed about the plants at the time of transplanting. To place the card, bend it slightly to open the slit, then slip it on to the center, the stem entering the slit, after which spread the card out flat, and press the points formed by the star-shaped cut snugly around the stem." Fumigating. An effective means of destroying insects in glass houses is by fumigating with various kinds of smoke or vapors. The best material to use for general purposes is some form of tobacco or tobacco compounds. The old method of fumigating with tobacco is to burn slowly slightly dampened tobacco stems in a kettle or scuttle, allowing the house to be filled with the pungent smoke. Lately, however, fluid extracts and other preparations of tobacco have been brought into use, and these are so effective that the tobacco-stem method is becoming obsolete. The use of hydrocyanic acid gas in greenhouses is now coming to be common, for plant-lice, white-fly, and other insects. It is also used to fumigate nursery stock for San José scale, and mills and dwellings for such pests and vermin as become established in them. The following directions are from Cornell Bulletin 252 (from which the formulas in the succeeding pages, and most of the advice, are also taken): "No general formula can be given for fumigating the different kinds of plants grown in greenhouses, as the species and varieties differ greatly in their ability to withstand the effects of the gas. Ferns and roses are very susceptible to injury, and fumigation if attempted at all should be performed with great caution. Fumigation will not kill insect eggs and thus must be repeated when the new brood appears. Fumigate only at night when there is no wind. Have the house as dry as possible and the temperature as near 60° as practicable. "Hydrocyanic acid gas is a deadly poison, and the greatest care is required in its use. Always use 98 to 100 per cent pure potassium cyanide and a good grade of commercial sulfuric acid. The chemicals are always combined in the following proportion: Potassium cyanide, 1 oz.; sulfuric acid, 2 fluid oz.; water, 4 fluid oz. Always use an earthen dish, pour in the water first, and add the sulfuric acid to it. Put the required amount of cyanide in a thin paper bag and when all is ready, drop it into the liquid and leave the room immediately. For mills and dwellings, use 1 oz. of cyanide for every 100 cu. ft. of space. Make the doors and windows as tight as possible by pasting strips of paper over the cracks. Remove the silverware and food, and if brass and nickel work cannot be removed, cover with vaseline. Place the proper amount of the acid and water for every room in 2-gal. jars. Use two or more in large rooms or halls. Weigh out the potassium cyanide in paper bags, and place them near the jars. When all is ready, drop the cyanide into the jars, beginning on the top floors, since the fumes are lighter than air. In large buildings, it is frequently necessary to suspend the bags of cyanide over the jars by cords running through screw eyes and all leading to a place near the door. By cutting all the cords at once the cyanide will be lowered into the jars and the operator may escape without injury. Let the fumigation continue all night, locking all outside doors and placing danger signs on the house." In greenhouses, the white-fly on cucumbers and tomatoes may be killed by overnight fumigation with 1 oz. of potassium cyanide to every 1000 cu. ft. of space; or with a kerosene emulsion spray or whale-oil soap, on plants not injured by these materials. The green aphis is dispatched in houses by fumigation with any of the tobacco preparations; on violets, by fumigation with 1/2 to 3/4 oz. potassium cyanide for every 1000 cu. ft. of space, leaving the gas in from 1/2 to 1 hr. The black aphis is more difficult to kill than the green aphis, but may be controlled by the same methods thoroughly used. Soaking tubers and seeds. Potato scab may be prevented, so far as planting infected "seed" is concerned, by soaking the seed tubers for half an hour in 30 gal. of water containing 1 pt. of commercial (about 40 per cent) formalin. Oats and wheat, when attacked by certain kinds of smut, may be rendered safe to sow by soaking for ten minutes in a similar solution. It is probable that some other tubers and seeds can be similarly treated with good results. Potatoes may also be soaked (for scab) one and one-half hours in a solution of corrosive sublimate, 1 oz. to 7 gal. of water. Spraying. The most effective means of destroying insects and fungi however, in any general or large way, is by the use of various sprays. The two general types of insecticides have already been mentioned those that kill by poisoning, and those that kill by destroying the body of the insect. Of the former, there are three materials in common use Paris green, arsenate of lead, and hellebore. Of the latter, the most usual at present are kerosene emulsion, miscible oils, and the lime-sulfur wash. Sprays for fungi usually depend for their efficiency on some form of copper or sulfur, or both. For surface mildews, as grape mildew, dusting flowers of sulfur on the foliage is a protection. In most cases, however, it is necessary to apply materials in liquid form, because they can be more thoroughly and economically distributed, and they adhere to the foliage better. The best general fungicide is the bordeaux mixture. It is generally, however, not advisable to use the bordeaux mixture on ornamental plants, because it discolors the foliage and makes the plants look very untidy. In such cases it is best to use the ammoniacal copper solution, which leaves no stain. In all spraying operations it is especially important that the applications be made the very moment the insect or disease is discovered, or in the case of fungous diseases, if one is expecting an attack, it is well to make an application of bordeaux mixture even before the disease appears.When the fungus once gets inside the plant tissue, it is very difficult to destroy it, inasmuch as fungicides act on these deep-seated fungi very largely by preventing their fruiting and their further spread on the surface of the leaf. For ordinary conditions, from two to four sprayings are necessary to dispatch the enemy. In spraying for insects in home gardens, it is often advisable to make a second application the day following the first one in order to destroy the remaining insects before they recover from the first treatment. There are many kinds of machines and devices for the application of sprays to plants. For a few individual specimens, the spray may be applied with a whisk, or with a common garden syringe. If one has a few trees to treat, however, it is best to have some kind of bucket pump like those shown in Figs. 221, 222. On a lawn or in a small garden a tank on wheels (Figs. 223, 224, 225) is handy and efficient. In such cases, or even for larger areas, some of the knapsack pumps (Figs. 219, 220) are very desirable. These machines are always serviceable, because the operator stands so near to his work; but as they carry a comparatively small quantity of liquid and do not throw it rapidly, they are expensive when much work is to be done. Yet, in ordinary home grounds, the knapsack pump or compressed-air pump is one of the most efficient and practicable of all the spraying devices. For large areas, as for small orchards and fields, a barrel pump mounted on a wagon is best. Common types of barrel pumps are shown in Figs. 226, 227, 228. Commercial plantations are now sprayed by power machines. There are many good patterns of spraying machines, and the intending purchaser should send for catalogues to the various manufacturers. The addresses may be found in the advertising pages of rural papers. As to nozzles for spraying it may be said that there is no one pattern that is best for all purposes. For most uses in home grounds the cyclone or vermorel type (Fig. 233) will give best satisfaction. The pump manufacturers supply special nozzles for their machines. Insecticide spraying formulas. The two classes of insecticides are here described, the poisons (arsenites and white hellebore) for chewing insects, as the beetles and all kinds of worms; the contact insecticides, as kerosene, oils, soap, tobacco, lime-sulfur, for plant-lice, scale, and insects in such position that the material cannot be fed to them (as maggots in the underground parts). Paris green The standard insecticidal poison. This is used in varying strengths, depending on the insect to be controlled and the kind of plant treated. Mix the Paris green into a paste and then add to the water. Keep the mixture thoroughly agitated while spraying. If for use on fruit trees, add 1 lb. of quick lime for every pound of Paris green to prevent burning the foliage. For potatoes it is frequently used alone, but it is much safer to use the lime. Paris green and bordeaux mixture may be combined without lessening the value of either, and the caustic action of the arsenic is prevented. The proportion of the poison to use is given under the various insects discussed in the succeeding pages. [...]... clear brown color one to one and one-half hours Cook in iron kettle in the open Add this amount to each fifty gallons of bordeaux for onions and cabbage For other plants difficult to wet, add this amount to every one hundred gallons of the mixture This mixture will prevent the bordeaux from being washed off by the heaviest rains Ammoniacal copper carbonate. Copper carbonate, 5 oz.; ammonia, 3 pt.; water,... water in the proportion of one pound to one gallon several hours before the solution is needed, the copper sulfate crystals being suspended in a sack near the top of the water A solution of copper sulfate is heavier than water As soon then, as the crystals begin to dissolve the solution will sink, keeping water in contact with the crystals In this way, the crystals will dissolve much sooner than if placed... of any unusual difficulty that he cannot control, the home-maker should take it up with the agricultural experiment station in the state, sending good specimens of the insect for identification He should also have the publications of the station The statements that are here made are intended as advice rather than as directions They are chosen from good authorities (mostly from Slingerland and Crosby... areas, and nearly all have reported them very effective; lamb's quarters (pigweed), pepper-grass, and mullein are among the weeds especially attractive to cutworms On small areas the making of the baits is done by hand, but they have been prepared on a large scale by spraying the plants in the field, cutting them with a scythe or machine, and pitching them from wagons in small bunches wherever desired... varieties least affected by it Take cuttings only from healthy plants Spray (in the field, once a week; in the greenhouse, once in two weeks) with copper sulfate, 1 lb to 20 gal of water Keep the greenhouse air as dry and cool as is compatible with good growth Keep the foliage free from moisture Train the plants so as to secure a free circulation of air among them Chestnut. The bark disease of chestnut... bordeaux, 5-5-50 Begin when the plants are 6 to 8 in high and repeat every 10 to 14 days during the season, making 5 to 7 applications in all Use 40 to 100 gal per acre at each application Under conditions exceptionally favorable to blight it will pay to spray as often as once a week Scab is caused by a fungus that attacks the surface of the tubers It is carried over on diseased tubers and in the soil... successful treatment is known In making new settings, use only plants from healthy plantations Remove the fruiting canes as soon as the fruit is gathered Red-rust is often serious on black varieties, but does not affect red ones It is the same as red rust of blackberry Dig up and destroy affected plants Rose diseases. Black leaf-spot is one of the commonest diseases of the rose It causes the leaves to fall... leaves to fall prematurely Spray with bordeaux, 5-5-50, beginning as soon as the first spots appear on the leaves Two or three applications at intervals of ten days will very largely control the disease Ammoniacal copper carbonate may be used on roses grown under glass Apply once a week until disease is under control For mildew on greenhouse roses, keep the steam pipes painted with a paste made of... leaves that fall to the ground In setting new plantations, remove all diseased leaves from the plants before they are taken to the field Soon after growth begins, spray the newly set plants with bordeaux, 5-5-50 Make three or four additional sprayings during the season The following spring, spray just before blossoming and again 10 to 14 days later If the bed is to be fruited a second time, mow the plants. .. July, depending on the season When the adults appear, jar them from the tree on sheets or curculio-catchers and destroy them To determine when they appear, jar a few trees daily, beginning the latter part of May in New York Currant-worm. In the spring the small green, black-spotted larvae feed on the foliage of currants and gooseberries, beginning their work on the lower leaves A second brood occurs . PROTECTING PLANTS FROM THINGS THAT PREY ON THEM Plants are preyed on by insects and fungi; and they are subject to various kinds of disease that, for the most part,. a clear brown color one to one and one-half hours. Cook in iron kettle in the open. Add this amount to each fifty gallons of bordeaux for onions and cabbage. For other plants difficult to wet,. away from plants. One of the best is to cover the plants with fine mosquito-netting or to grow them in hand-frames, or to use a wire-covered box like that shown in Fig. 229. In growing plants