Fig. 95.Fig. 95. Dewberries
A serious disease, the watermelon wilt, is rapidly spreading through melon-growing sections. This disease is caused by germs in the soil, and the germs are hard to kill. If the wilt should appear in your neighborhood, do not allow any stable manure to be used on your melon land, for the germs are easily scattered by means of stable manure. The germs also cling to the seeds of diseased melons, and these seeds bear the disease to other fields. If you treat melon seeds as you are directed on page 135 to treat oat seeds, the germs on the seeds will be destroyed. By crossing the watermelon on the citron melon, a watermelon that is resistant to wilt has recently been developed and successfully grown in soils in which wilt is present. The new melon, inferior in flavor at first, is being improved from season to season and bids fair to rival other melons in flavor.
Fig. 96.Fig. 96. An Easy Way to beautify the Home
Fig. 97.Fig. 97. A Back Yard to refinethe Children of the Family
The comforts and joys of life depend largely upon small things. Of these small things perhaps none holds a position of greater importance in country life than the adornment of the home, indoors and outdoors, with flowers tastefully arranged. Their selection and planting furnish pleasant recreation; their care is a pleasing employment; and each little plant, as it sprouts and grows and develops, may become as much a pet as creatures of the sister animal kingdom. A beautiful, well-kept yard adds greatly to the pleasure and attractiveness of a country home. If a beautiful yard and home give joy to the mere passer-by, how much more must their beauty appeal to the owners. The decorating of the home shows ambition, pride, and energy—important elements in a successful life.
Plant trees and shrubs in your yard and border your masses ofshrubbery with flower-beds. Do not disfigure a lawn by placing a bed of flowers in it. Use the flowers rather to decorate the shrubbery, and for borders along walks, and in the corners near steps, or against foundations.
If you wish to raise flowers for the sake of flowers, not as decorations, make the flower-beds in the back yard or at the side of the house.
Plants may be grown from seeds or from bulbs or from cuttings. The rooting of cuttings is an interesting task to all who are fond of flowers. Those who have no greenhouse and who wish to root cuttings of geraniums, roses, and other plants may do so in the following way. Take a shallow pan, an old-fashioned milk pan for instance, fill it nearly full of clean sand, and then wet the sand thoroughly. Stick the cuttings thickly into this wet sand, set the pan in a warm, sunny window, and keep the sand in the same water-soaked condition. Most cuttings will root well in a few weeks and may then be set into small flower-pots. Cuttings of tea roses should have twoor three joints and be taken from a stem that has just made a flower. Allow one of the rose leaves to remain at the top of the cutting. Stick this cutting into the sand and it will root in about four weeks. Cuttings of Cape jasmine may be rooted in the same way. Some geraniums, the rose geranium for example, may be grown from cuttings of the roots.
Fig. 98.Fig. 98. Repotting
Fig. 99.Fig. 99. A Clematis
Bulbs are simply the lower ends of the leaves of a plant wrapped tightly around one another and inclosing the bud that makes the future flower-stalk. The hyacinth, the narcissus, and the common garden onion are examples of bulbous plants. The flat part at the bottom of the bulb is the stem of the plant reduced to a flat disk, and between each two adjacent leaves on this flat stem there is a bud, just as above-ground there is a bud at the base of a leaf. These buds on the stem of the bulb rarely grow, however, unless forced todo so artificially. The number of bulbs may be greatly increased by making these buds grow and form other bulbs. In increasing hyacinths the matured bulbs are dug in the spring, and the under part of the flat stem is carefully scraped away to expose the base of the buds. The bulbs are then put in heaps and covered with sand. In a few weeks each bud has formed a little bulb. The gardener plants the whole together to grow one season, after which the little bulbs are separated and grown into full-sized bulbs for sale. Other bulbs, like the narcissus or the daffodil, form new bulbs that separate without being scraped.
There are some other plants which have underground parts that are commonly called bulbs but which are not bulbs at all; for example, the gladiolus and the caladium, or elephant's ear. Their underground parts are bulblike in shape, but are really solid flattened stems with eyes like the underground stem of the Irish potato. These parts are calledcorms. They may be cut into pieces like the potato and each part will grow.
The dahlia makes a mass of roots that look greatly like sweet potatoes, but there are no eyes on them as there are on the sweet potato. The only eyes are on the base of thestem to which they are joined. They may be sprouted like sweet potatoes and then soft cuttings made of the green shoots, after which they may be rooted in the greenhouse and later planted in pots.
There are many perennial plants that will bloom the first season when grown from the seed, though such seedlings are seldom so good as the plants from which they came. They are generally used to originate new varieties. Seeds of the dahlia, for instance, can be sowed in a box in a warm room in early March, potted as soon as the plants are large enough to handle, and finally planted in the garden when the weather is warm. They will bloom nearly as soon as plants grown by dividing the roots or from cuttings.
Fig. 100.Fig. 100. Outdoor-Grown Chrysanthemums
Fig. 101.Fig. 101. The Carnation (Eldorado)
In growing annual plants from seed, there is little difficulty if the grower has a greenhouse or a hotbed with a glass sash. Even without these the plants may be grown in shallow boxes in a warm room. The best boxes are about four inches deep with bottoms made of slats nailed a quarter of an inch apart to give proper drainage. Some moss is laid over the bottom to prevent the soil from sifting through. The boxes should then be filled with light, rich soil. Fine black forest mold, thoroughly mixed with one fourth its bulk of well-rottedmanure, makes the best soil for filling the seed-boxes. If this soil be placed in an oven and heated very hot, the heat will destroy many weeds that would otherwise give trouble. After the soil is put in the boxes it should be well packed by pressing it with a flat wooden block. Sow the seeds in straight rows, and at the ends of the rows put little wooden labels with the names of the flowers on them.
Fig. 102.Fig. 102. The Poet's Narcissus
Seeds sowed in the same box should be of the same general size in order that they may be properly covered, for seeds need to be covered according to their size. After sowing the seed, sift the fine soil over the surface of the box. The best soil for covering small seeds is made by rubbing dry moss and leaf-mold through a sieve together. This makes a light cover that will not bake and will retain moisture. After covering the seeds, press the soil firm and smooth with a wooden block. Now sprinkle the covering soil lightly with a watering-pot until it is fairly moistened. Lay some panes of glass over the box to retain the moisture, and avoid further watering until moisture becomes absolutely necessary. Too much watering makes the soil too compact and rots the seed.
As soon as the seedlings have made a second pair of leaves, take them up with the point of a knife and transplant them into other boxes filled in the same way. They should be set two inches apart so as to give them room to grow strong. They may be transplanted from the boxes to the flower-garden by taking an old knife-blade and cutting the earth into squares, and then lifting the entire square with the plant and setting it where it is wanted.
Fig. 103.Fig. 103. A Cyclamen
There are many flower-seeds which are so small that they must not be covered at all. In this class we find begonias, petunias, and Chinese primroses. To sow these prepare boxes as for the other seeds, and press the earth smooth. Then scatter some fine, dry moss thinly over the surface of the soil. Sprinkle this with water until it is well moistened, and at once scatter the seeds thinly over the surface and cover the boxes with panes of glass until the seeds germinate. Transplant as soon as the young plants can be lifted out separately on the blade of a penknife.
Fig. 104.Fig. 104. A Modern Sweet Pea
Many kinds of flower-seeds may be sowed directly in the open ground where they are to remain. The sweet pea is one of the most popular flowers grown in this way. The seeds should be sowed rather thickly in rows and covered fully four inchesdeep. The sowing should be varied in time according to the climate. From North Carolina southward, sweet peas may be sowed in the fall or in January, as they are very hardy and should be forced to bloom before the weather becomes hot. Late spring sowing will not give fine flowers in the South. From North Carolina northward the seeds should be sowed just as early in the spring as the ground can be easily worked. When the plants appear, stakes should be set along the rows and a strip of woven-wire fence stretched for the plants to climb on. Morning-glory seeds are also sowed where they are to grow. The seeds of the moonflower are large and hard and will fail to grow unless they are slightly cut. To start their growth make a slight cut just through the hard outer coat of the seed so as to exposethe white inside. In this way they will grow very readily. The seeds of the canna, or Indian-shot plant, are treated in a similar way to start them growing.
Fig. 105.Fig. 105. Dahlias
The canna makes large fleshy roots which in the North are taken up, covered with damp moss, and stored under the benches of the greenhouse or in a cellar. If allowed to get too dry, they will wither. From central North Carolina south it is best to cover them up thickly with dead leaves and let them stay in the ground where they grew. In the early spring take them up and divide for replanting.
Perennial plants, such as our flowering shrubs, are grown from cuttings of the ripe wood after the leaves have fallen in autumn. From North Carolina southward these cuttings should be set in rows in the fall. Cuttings ten inches long are set so that the tops are just even with the ground. A light cover of pine leaves will prevent damage from frost. Farther north the cuttings should be tied in bundles and well buried in the ground with earth heaped over them. In the spring set them in rows for rooting. In the South all the hardy hybrid perpetual roses can be grownin this way, and in any section the cuttings of most of the spring-flowering shrubs will grow in the same manner. The Japanese quince, which makes such a show of its scarlet flowers in early spring, can be best grown from three-inch cuttings made of the roots and planted in rows in the fall.
Many of our ornamental evergreen trees, such as the arbor vitæ, can be grown in the spring from seeds sowed in a frame. Cotton cloth should be stretched over the trees while they are young, to prevent the sun from scorching them. When a year old they may be set in nursery rows to develop until they are large enough to plant. Arbor vitæ may also be grown from cuttings made by setting young tips in boxes of sand in the fall and keeping them warm and moist through the winter. Most of them will be rooted by spring.
Fig. 106.Fig. 106. Four-O'clocks set in a Good Place
The kinds of flowers that you can grow are almost countless. You can hardly make a mistake in selecting, as all areinteresting. Start this year with a few and gradually increase the number under your care year by year, and aim always to make your plants the choicest of their kind.
Of annuals there are over four hundred kinds cultivated. You may select from the following list: phlox, petunias, China asters, California poppies, sweet peas, pinks, double and single sunflowers, hibiscus, candytuft, balsams, morning-glories, stocks, nasturtiums, verbenas, mignonette.
Fig. 107.Fig. 107. A Window Box
Of perennials select bleeding-hearts, pinks, bluebells, hollyhocks, perennial phlox, perennial hibiscus, wild asters, and goldenrods. From bulbs choose crocus, tulip, daffodil, narcissus, lily of the valley, and lily.
Some climbers are cobæa, honeysuckle, Virginia creeper, English ivy, Boston ivy, cypress vine, hyacinth bean, climbing nasturtiums, and roses.
Fig. 108.Fig. 108. A Window-Garden
To make your plants do best, cultivate them carefully. Allow no weeds to grow among them and do not let the surface of the soil dry into a hard crust. Beware, however, of stirring the soil too deep. Loosening the soil about the roots interrupts the feeding of the plant and does harm. Climbing plants may be trained to advantage on low woven-wire fences. These are especially serviceable for sweet peas and climbing nasturtiums. Do not let the plants go to seed, since seeding is a heavy drain on nourishment. Moreover, the plant has served its end when it seeds and is ready then to stop blossoming. You should therefore pick off the old flowers to prevent their developing seeds. This will cause many plants which would otherwise soon stop blossoming to continue bearing flowers for a longer period.
Fig. 109.Fig. 109. An Inside Window Box in its Full Glory
Window-Gardening.Growing plants indoors in the window possesses many of the attractions of outdoor flower-gardening, and is a means of beautifying the room at very small expense. Especially do window-gardens give delight during the barren winter time. They are a source of culture and pleasure to thousands who cannot afford extended and expensive ornamentation.
The window-garden may vary in size from an eggshell holding a minute plant to boxes filling all the available space about the window. The soil may be in pots for individualplants or groups of plants or in boxes for collections of plants. You may raise your flowers inside of the window on shelves or stands, or you may have a set of shelves built outside of the window and inclosed in glazed sashes. The illustration on page 119 gives an idea of such an external window-garden.
Fig. 110.Fig. 110. Making the Outside of a Window Bloom
The soil must be rich and loose. The best contains some undecayed organic matter such as leaf-mold or partly decayed sods and some sand. Raise your plants from bulbs, cuttings, or seed, just as in outdoor gardens. Some plants do better in cool rooms, others in a warmer temperature.
If the temperature ranges from 35° to 70°, averaging about 55°, azaleas, daisies, carnations, candytuft, alyssum, dusty miller, chrysanthemums, cinerarias, camellias, daphnes, geraniums, petunias, violets, primroses, and verbenas make especially good growths.
A BEAUTIFUL WINDOW FLOWERA BEAUTIFUL WINDOW FLOWER
If the temperature is from 50° to 90°, averaging 70°, try abutilon, begonia, bouvardia, caladium, canna, Cape jasmine, coleus, fuchsia, gloxinia, heliotrope, lantana, lobelia, roses, and smilax.
If your box or window is shaded a good part of the time, raise begonias, camellias, ferns, and Asparagus Sprengeri.
Fig. 111.Fig. 111. Ferns for Both Indoors and Outdoors
When the soil is dry, water it; then apply no more water until it again becomes dry. Beware of too much water. The plants should be washed occasionally with soapsuds and then rinsed. If red spiders are present, sponge them off with water as hot as can be borne comfortably by the hand. Newspapers afford a good means of keeping off the cold.
Plants have diseases just as animals do; not the same diseases, to be sure, but just as serious for the plant. Some of them are so dangerous that they kill the plant; others partly or wholly destroy its usefulness or its beauty. Some diseases are found oftenest on very young plants, others prey on the middle-aged tree, while still others attack merely the fruit. Whenever a farmer or fruit-grower has disease on his plants, he is sure to lose much profit.
You have all seen rotten fruit. This is diseased fruit. Fruit rot is a plant disease. It costs farmers millions of dollars annually. A fruit-grower recently lost sixty carloads of peaches in a single year through rot which could have been largely prevented if he had known how.
Fig. 112.Fig. 112. Tangled Threads of Blue Mold
Many of the yellowish or discolored spots on leaves are the result of disease, as is also the smut of wheat, corn, and oats, the blight of the pear, and the wilt of cotton. Many of these diseases are contagious, or, as we often hear said of measles, "catching." This is true, among others, of the apple and peach rots. A healthy apple can catch this disease from a sick apple. You often see evidence of this in the apple bin. So, too, many of the diseases found in the field or garden are contagious.
Sometimes when the skin of a rotten apple has been broken you will find in the broken place a blue mold. It was this that caused the apple to decay. This mold is a living plant; very small, certainly, but nevertheless a plant. Let us learn a little about molds, in order that we may better understand our apple and potato rots, as well as other plant diseases.
If you cut a lemon and let it stand for a day or two, there will probably appear a blue mold like that you have seen on the surface of canned fruit. Bread also sometimes has this blue mold; at other times bread has a black mold, and yet again a pink or a yellow mold.
These and all other molds are tiny living plants. Instead of seeds they produce many very small bodies that serve the purpose of seeds and reproduce the mold. These are calledspores. Fig. 112 shows how they are borne on the parent plant.
Fig. 113.Fig. 113. Magnified Rose Mildew
Fig. 114.Fig. 114. A Mildewed Rose
It is also of great importance to decide whether by keeping the spores away we may prevent mold. Possibly this experiment will help us. Moisten a piece of bread, then dip a match or a pin into the blue mold on a lemon, and draw the match across the moist bread. You will thus plant the spores in a row, though they are so small that perhaps you may not see any of them. Place the bread in a damp placefor a few days and watch it. Does the mold grow where you planted it? Does it grow elsewhere? This experiment should prove to you that molds are living things and can be planted. If you find spots elsewhere, you must bear in mind that these spores are very small and light and that some of them were probably blown about when you made your sowing. When you touch the moldy portion of a dry lemon, you see a cloud of dust rise. This dust is made of millions of spores.
If you plant many other kinds of mold you will find that the molds come true to the kind that is planted; that like produces like even among molds.
You can prove, also, that the mold is caused only by other mold. To do this, put some wet bread in a wide-mouthed bottle and plug the mouth of the bottle with cotton. Kill all the spores that may be in this bottle by steaming it an hour in a cooking-steamer. This bread will not mold until you allow live mold from the outside to enter. If, however, at any timeyou open the bottle and allow spores to enter, or if you plant spores therein, and if there be moisture enough, mold will immediately set in.
Fig. 115.Fig. 115. A Highly Magnified Section of Diseased Pear LeafShowing how spores are borne
The little plants which make up these molds are calledfungi. Some fungi, such as the toadstools, puffballs, and devil's snuff-box, are quite large; others, namely the molds, are very small; and others are even smaller than the molds. Fungi never have the green color of ordinary plants, always reproduce by spores, and feed on living matter or matter that was once alive. Puffballs, for example, are found on rotting wood or dead twigs or roots. Some fungi grow on living plants,and these produce plant disease by taking their nourishment from the plant on which they grow; the latter plant is called thehost.
The same blue mold that grows on bread often attacks apples that have been slightly bruised; it cannot pierce healthy apple skin. You can plant the mold in the bruised apple just as you did on bread and watch its rapid spread through the apple. You learn from this the need of preventing bruised or decayed apples from coming in contact with healthy fruit.
Fig. 116.Fig. 116. Spores of the Pear ScabThe spores are borne on stalks
Just as the fungus studied above lives in the apple or bread, so other varieties live on leaves, bark, etc. Fig. 113 represents the surface of a mildewed rose leaf greatly magnified. This mildew is a fungus. You can see its creeping stems, its upright stalk, and numerous spores ready to fall off and spread the disease with the first breath of wind. You must remember that this figure is greatly magnified, and that the whole portion shown in the figure is only about one tenth of an inch across. Fig. 114 shows the general appearance of a twig affected by this disease.
Mildew on the rose or on any other plant may be killed by spraying the leaves with a solution of liver of sulphur; to make this solution, use one ounce of the liver of sulphur to two gallons of water.
The fungus that causes the pear-leaf spots has its spores in little pits (Fig. 115). The spores of some fungi also grow on stalks, as shown in Fig. 116. This figure represents an enlarged view of the pear scab, which causes so much destruction.
You see, then, that fungi are living plants that grow at the expense of other plants and cause disease. Now if you can cover the leaf with a poison that will kill the spore when it comes, you can prevent the disease. One such poison is the Bordeaux (bôr-dō') mixture, which has proved of great value to farmers.
Since the fungus in most cases lives within the leaves, the poison on the outside does no good after the fungus is established. The treatment can be used only topreventattack, not to cure, except in the case of a few mildews that live on the outside of the leaf, as does the rose mildew.
EXERCISEWhy do things mold more readily in damp places? Do you now understand why fruit is heated before it is canned? Try to grow several kinds of mold. Do you know any fungi which may be eaten?Transfer disease from a rotten apple to a healthy one and note the rapidity of decay. How many really healthy leaves can you find on a strawberry plant? Do you find any spots with reddish borders and white centers? Do you know that this is a serious disease of the strawberry? What damage does fruit mold do to peaches, plums, or strawberries?Write to your experiment station for bulletins on plant diseases and methods for making and using spraying mixtures.
EXERCISE
Why do things mold more readily in damp places? Do you now understand why fruit is heated before it is canned? Try to grow several kinds of mold. Do you know any fungi which may be eaten?
Transfer disease from a rotten apple to a healthy one and note the rapidity of decay. How many really healthy leaves can you find on a strawberry plant? Do you find any spots with reddish borders and white centers? Do you know that this is a serious disease of the strawberry? What damage does fruit mold do to peaches, plums, or strawberries?
Write to your experiment station for bulletins on plant diseases and methods for making and using spraying mixtures.
Can you imagine a plant so small that it would take one hundred plants lying side by side to equal the thickness of a sheet of writing-paper? There are plants that are so small. Moreover, these same plants are of the utmost importance to man. Some of them do him great injury, while others aid him very much.
You will see their importance when you are told that certain of them in their habits of life cause great change in the substances in which they live. For example, when living in a sugary substance they change the sugar into a gas and an alcohol. Do you remember the bright bubbles of gas you have seen rising in sweet cider or in wine as it soured? These bubbles are caused by one of these small plants—the yeast plant. As the yeast plant grows in the sweet fruit juice, alcohol is made and a gas is given off at the same time, and this gas makes the bubbles.
Fig. 117.Fig. 117. Yeast PlantsA, a single plant;B, group of two budding cells;C, group of several cells
Later, other kinds of plants equally small will grow and change the alcohol into an acid which you will recognize as vinegar by its sour taste and peculiar odor. Thus vinegar is made by the action of two different kinds of little living plants in the cider. That these are living beings you can prove by heating the cider and keeping it tightly sealed so that nothing can enter it. You will find that because the living germs have been killed by the heat, the cider will not ferment or sour as it did before. The germs could of course be killed by poisons, but then the cider would be unfit for use. It is this same little yeast plant that causes bread to rise.
When you see any decaying matter you may know that in it minute plants much like the yeast plant are at work. Since decay is due to them, we take advantage of the fact that they cannot grow in strong brine or smoke; and we prepare meat for keeping by salting it or by smoking it or by both of these methods.
Fig. 118.Fig. 118. Forms of Bacteriaa, grippe;b, bubonic plague;c, diphtheria;d, tuberculosis;e, typhoid fever
You see that some of the yeast plants andbacteria, as many of these forms are called, are very friendly to us, while others do us great harm.
Some bacteria grow within the bodies of men and other animals or in plants. When they do so they may produce disease. Typhoid fever, diphtheria, consumption, and many other serious diseases are caused by bacteria. Fig. 118,e, shows the bacterium that causes typhoid fever. In the picture, of course, it is very greatly magnified. In reality these bacteria are so small that about twenty-five thousand of them side by side would extend only one inch. These small beings produce their great effects by very rapid multiplication and by giving off powerful poisons.
Bacteria are so small that they are readily borne on the dust particles of the air and are often taken into the body through the breath and also through water or milk. You can therefore see how careful you should be to prevent germs from getting into the air or into water or milk when there is disease about your home. You should heed carefully all instructions of your physician on this point, so that you may not spread disease.
In the last two sections you have learned something of the nature of those fungi and bacteria that cause disease in animals and plants. Now let us see how we can use this knowledge to lessen the diseases of our crops. Farmers lose through plant diseases much that could be saved by proper precaution.
First, you must remember that every diseased fruit, twig, or leaf bears millions of spores. These must be destroyed by burning. They must not be allowed to lie about and spread the disease in the spring. See that decayed fruit in the bin or on the trees is destroyed in the same manner. Never throw decayed fruit into the garden or orchard, as it may cause disease the following year.
Second, you can often kill spores on seeds before they are planted and thus prevent the development of the fungus (see pp.134-137).
Third, often the foliage of the plant can be sprayed with a poison that will prevent the germination of the spores (see pp.138-140).
Fourth, some varieties of plants resist disease much more stoutly than others. We may often select the resistant form to great advantage (see Fig. 119).
Fifth, after big limbs are pruned off, decay often sets in at the wound. This decay may be prevented by coating the cut surface with paint, tar, or some other substance that will not allow spores to enter the wound or to germinate there.
Sixth, it frequently happens that the spore or fungus remains in the soil. This is true in the cotton wilt, and the remedy is so to rotate crops that the diseased land is not used again for this crop until the spores or fungi have died.
Fire-Blight of the Pear and Apple.You have perhaps heard your father speak of the "fire-blight" of pear and apple trees. This is one of the most injurious and most widely known of fruit diseases. Do you want to know the cause of this disease and how to prevent it?
First, how will you recognize this disease? If the diseased bough at which you are looking has true fire-blight, you will see a blackened twig with withered, blackened leaves. During winter the leaves do not fall from blighted twigs as they do from healthy ones. The leaves wither because of the diseased twig, not because they are themselves diseased. Only rarely does the blight really enter the leaf. Sometimes a sharp line separates the blighted from the healthy part of the twig.
This disease is caused by bacteria, of which you have read in another section. The fire-blight bacteria grow in the juicy part of the stem, between the wood and the bark. This tender, fresh layer (as explained on page 79) is called thecambium, and is the part that breaks away and allows you to slip the bark off when you make your bark whistle in the spring. The growth of new wood takes place in the cambium, and this part of the twig is therefore full of nourishment. If this nourishment is stolen the plant of course soon suffers.
The bacteria causing fire-blight are readily carried from flower to flower and from twig to twig by insects; therefore to keep these and other bacteria away from your trees you must see to it that all the trees in the neighborhood of your orchard are kept free from mischievous enemies. If harmful bacteria exist in near-by trees, insects will carry them to your orchard. You must therefore watch all the relatives of the pear; namely, the apple, hawthorn, crab, quince, and mountain ash, for any of these trees may harbor the germs.
Fig. 119.Fig. 119. A Resistant Variety of Sea Island Cotton
Fig. 120.Fig. 120. Fire-BlightBacteriaMagnified
When any tree shows blight, every diseased twig on it must be cut off and burned in order to kill the germs, and you must cut low enough on the twig to get all the bacteria. It is best to cut a foot below the blackened portion. If by chance your knife should cut into wood containing the livinggerms, and then you should cut into healthy wood with the same knife, you yourself would spread the disease. It is therefore best after each cutting to dip your knife into a solution of carbolic acid. This will kill all bacteria clinging to the knife-blade. The surest time to do complete trimming is after the leaves fall in the autumn, as diseased twigs are most easily recognized at that time, but the orchard should be carefully watched in the spring also. If a large limb shows the blight, it is perhaps best to cut the tree entirely down. There is little hope for such a tree.
A large pear-grower once said that no man with a sharp knife need fear the fire-blight. Yet our country loses greatly by this disease each year.
It may be added that winter pruning tends to make the tree form much new wood and thus favors the disease. Rich soil and fertilizers make it much easier in a similar way for the tree to become a prey to blight.
EXERCISEAsk your teacher to show you a case of fire-blight on a pear or apple tree. Can you distinguish between healthy and diseased wood? Cut the twig open lengthwise and see how deep into the wood and how far down the stem the disease extends. Can you tell surely from the outside how far the twig is diseased? Can you find any twig that does not show a distinct line of separation between diseased and healthy wood? If so, the bacteria are still living in the cambium. Cut out a small bit of the diseased portion and insert it under the bark of a healthy, juicy twig within a few inches of its tip and watch it from day to day. Does thetree catch the disease? This experiment may prove to you how easily the disease spreads. If you should see any drops like dew hanging from diseased twigs, touch a little of this moisture to a healthy flower and watch for results.Cut and burn all diseased twigs that you can find. Estimate the damage done by fire-blight.Farmers' bulletins on orchard enemies are published by the Department of Agriculture, Washington, D.C., and can be had by writing for them. They will help your father much in treating fire-blight.
EXERCISE
Ask your teacher to show you a case of fire-blight on a pear or apple tree. Can you distinguish between healthy and diseased wood? Cut the twig open lengthwise and see how deep into the wood and how far down the stem the disease extends. Can you tell surely from the outside how far the twig is diseased? Can you find any twig that does not show a distinct line of separation between diseased and healthy wood? If so, the bacteria are still living in the cambium. Cut out a small bit of the diseased portion and insert it under the bark of a healthy, juicy twig within a few inches of its tip and watch it from day to day. Does thetree catch the disease? This experiment may prove to you how easily the disease spreads. If you should see any drops like dew hanging from diseased twigs, touch a little of this moisture to a healthy flower and watch for results.
Cut and burn all diseased twigs that you can find. Estimate the damage done by fire-blight.
Farmers' bulletins on orchard enemies are published by the Department of Agriculture, Washington, D.C., and can be had by writing for them. They will help your father much in treating fire-blight.
Oat Smuts.Let us go out into a near-by oat field and look for all the blackened heads of grain that we can find. How many are there? To count accurately let us select an area one foot square. We must look carefully, for many of these blackened heads are so low that we shall not see them at the first glance. You will be surprised to find as many as thirty or forty heads in every hundred so blackened. These blackened heads are due to a plant disease calledsmut.
Fig. 121.Fig. 121. Loose Smutof OatsThe glumes atamore nearly destroyedthan the glumes atb
Fig. 122.Fig. 122. A Crop from Oatstreated with Formalin
When threshing-time comes you will notice a great quantity of black dust coming from the grain as it passes through the machine. The air is full of it. This black dust consists of the spores of a tiny fungous plant. The fungous smut plant grows upon the oat plant, ripens its spores in the head, and is ready to be thoroughly scattered among the grains of the oats as they come from the threshing-machine.
These spores cling to the grain and at the next planting are ready to attack the sprouting plantlet. A curious thing about the smut is that it can gain a foothold only on veryyoung oat plants; that is, on plants about an inch long or of the age shown in Fig. 121.
When grain covered with smut spores is planted, the spores develop with the sprouting seeds and are ready to attack the young plant as it breaks through the seed-coat. You see, then, how important it is to have seed grain free from smut. A substance has been found that will, without injuring the seeds, kill all the smut spores clinging to the grain. This substance is calledformalin. Enough seed to plant a whole acre can be treated with formalin at a cost of only a few cents. Such treatment insures a full crop and clean seed for future planting. Try it if you have any smut.
Fig. 122 illustrates what may be gained by using seeds treated to prevent smut. The annual loss to the farmers of the United States from smut on oats amounts to several millions of dollars. All that is needed to prevent this loss is a little care in the treatment of seed and a proper rotation of crops.
EXERCISECount the smutted heads on a patch three feet square and estimate the percentage of smut in all the wheat and oat fields near your home. On which is it most abundant? Do you know of any fields that havebeen treated for smut? If so, look for smut in these fields. Ask how they were treated. Do you know of any one who uses bluestone for wheat smut? Can oats be treated with bluestone?At planting time get an ounce of formalin at your drug store or from the state experiment station. Mix this with three gallons of water. This amount will treat three bushels of seeds. Spread the seeds thinly on the barn floor and sprinkle them with the mixture, being careful that all the seeds are thoroughly moistened. Cover closely with blankets for a few hours and plant very soon after treatment. Try this and estimate the per cent of smut at next harvest-time. Write to your experiment station for a bulletin on smut treatment.
EXERCISE
Count the smutted heads on a patch three feet square and estimate the percentage of smut in all the wheat and oat fields near your home. On which is it most abundant? Do you know of any fields that havebeen treated for smut? If so, look for smut in these fields. Ask how they were treated. Do you know of any one who uses bluestone for wheat smut? Can oats be treated with bluestone?
At planting time get an ounce of formalin at your drug store or from the state experiment station. Mix this with three gallons of water. This amount will treat three bushels of seeds. Spread the seeds thinly on the barn floor and sprinkle them with the mixture, being careful that all the seeds are thoroughly moistened. Cover closely with blankets for a few hours and plant very soon after treatment. Try this and estimate the per cent of smut at next harvest-time. Write to your experiment station for a bulletin on smut treatment.
Fig. 123.Fig. 123. A Scabby Seed Potato
Fig. 124.Fig. 124. A Healthy Seed Potato
Potato Scab.The scab of the white, or Irish, potato is one of the commonest and at the same time most easily prevented of plant diseases. Yet this disease diminishes the profits of the potato-grower very materially. Fig. 123 shows a very scabby potato, while Fig. 124 represents a healthy one. This scab is caused by a fungous growth on the surface of the potato. Of course it lessens the selling-price of the potatoes. If seed potatoes be treated to a bath of formalin just before they are planted, the formalin will kill the fungi on the potatoes and greatly diminish the amount of scab at the next harvest. Therefore before they are planted, seed potatoes should be soaked in a weak solution of formalin for about two hours. One-half pint of formalin to fifteen gallons of water makes a proper solution.
Fig. 125.Fig. 125.From a scabby potato,like the one in Fig. 123,this yield was obtained
Fig. 126.Fig. 126.From a healthy potato,like the one in Fig. 124,this yield was obtained
One pint of formalin, or enough for thirty gallons of water, will cost but thirty-five cents. Since this solution can be used repeatedly, it will do for many bushels of seed potatoes.
Fig. 127.Fig. 127. Effect of SprayingSprayed potatoes on left; unsprayed on right
Late Potato Blight.The blight is another serious disease of the potato. This is quite a different disease from the scab and so requires different treatment. The blight is caused by another fungus, which attacks the foliage of the potato plant. When the blight seriously attacks a crop, it generally destroys the crop completely. In the year 1845 a potato famine extending over all the United States and Europe was caused by this disease.
Fig. 128.Fig. 128. Yield from Two Fields of the Same SizeThe one at the top was sprayed; the one at the bottom was unsprayed
Spraying is the remedy for potato blight. Fig. 128 shows the effect of spraying upon the yield. In this case the sprayed field yielded three hundred and twenty-four bushels an acre, while the unsprayed yielded only one hundred bushels to an acre. Fig. 127 shows the result of three applications of the spraying mixture on the diseased field. Figs. 129 and 130 show how the spraying is done.