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Weeds - Plants Enemies

( Originally Published 1915 )



Weed Study in Nature Study.—If a child has had a good course in nature study, such as that outlined by Schmucker in his book, " The Study of Nature," or by Hodge in " Nature Study and Life," before he begins the study of agriculture the child has learned of some five or ten plants each year, for five or six years. This nature study work should have implanted in the child a love for the wild flowers and it should have taught him some things to do to help preserve them. His nature study should have taught him to know five or ten poisonous plants and how they poison. His school garden work has taught him how to grow many of the cultivated flowers and vegetables.

When the child comes to the study of agriculture in the seventh and eighth grades or, better, in the high school, he should learn to identify ten to twenty of the common and troublesome weeds. He should learn to know them from seed, leaf, stem, or sprouting seedling. This he may have learned in his nature study. After one has learned to identify a weed, he is ready for what should be the first step in agriculture, namely, to learn how to control or eradicate it in the most economical and efficient way.

Weed Booklets.—Some of the members of the class, if not all, should make a booklet on weeds. They should learn that the sources of information for a topic in agriculture are the same as the sources of information for any topic that one may have to write upon. Our sources of information may be classified under four heads, and pupils should use each of them. They are : First, observation; second, conversation with well-informed people; third, reading; and fourth, meditation. The well-informed people should include the best farmers of the district and the men at the Experiment Stations and the National Department of Agri-culture. He may, however, have to be content to learn from this latter class by reading their bulletins and books. The point I wish to make is that the learning of reliable sources of information and how to tell which are reliable, is just as valuable as the learning of some fact in agriculture. The old adage tells us : " The next best thing to knowing a thing is to know where to find out about it." By the time the child becomes a farmer there may have been discovered better ways than the ones we are now teaching, hence he needs to know where to get the best that there is to be learned on the different subjects.

In his study of plant diseases the student learned of plants that are man's enemies. Most of these are microscopic plants. There remain to be studied a large class of plants against which man has fought for ages. During this fight, by the law of the " survival of the fittest," these plants have inherited the tendency to come up where man least expects them, to come up at times when he cannot get at them, to survive after his hoe or cultivator has passed over them, and to multiply in incredible numbers so as to insure the survival of some of the species. Most of these plants were brought to America from Europe. Man has fought them, and will have to fight them, through human history.

Benefits from Weeds.—As in most things there is some good so there is in weeds. Weeds may add humus to the soil, though it may be humus that is poison to the cultivated crops. Weeds have compelled man to cultivate the soil and thus have the benefit of tillage. Many of the weeds help in preventing erosion, and some of them help to beautify the landscape by covering the scars made by wheel and pick and hoof. Many weeds furnish valuable drugs and medicines.

Definitions of Weeds.—Some one has said that a weed is a plant growing where a man does not want it; in this sense extra corn plants in a field are weeds. The farmer generally thinks of weeds as plants which his stock do not use and which grow in spite of his efforts to rid his place of them. The term weeds is not applied to bacteria and fungi but is used for the higher plants only. In this sense a weed is a plant able to take care of itself under any and all conditions.

What Farmers Lose by Weeds.—It is estimated that the farmers of the United States lose each year somewhat over $100,000,000 from weeds. Professor Pammel, in his recent book on " Weeds on the Farm and Garden," says that the farmers of the single State of Iowa lose between $7,000,000 and $9,000,000 each year on weeds alone.

Weeds injure a field in any one or more of a number of ways : The weeds may use the available plant food of which there may be but little at any one time; in this way weeds will prevent a tenant from getting what he pays rent for. Weeds use moisture, from 300 to 500 pounds for each pound of weedy, dry matter produced, and this lost moisture may be seriously needed by the cultivated crop during dry weather. Weeds often make a very dense growth near the ground; this holds moisture, condenses dew, harbors insects, and may conduce to plant diseases ; the weeds should be taken out and the plants thinned so as to insure a free circulation of air. The development of plant diseases is especially noticeable in weedy oat and wheat fields, which are much more likely to rust. Some weeds harbor plant diseases ; mustard, for example, harbors club root which is transmissible to cabbages and other cruciferous plants. Members of the mallow family harbor a root rot that later attacks the cotton plants. Some weeds secrete a poison for the cereals ; this is believed to be true of cocklebur for corn. Other weeds are poisonous to man and the domestic animals; cow bane and water parsnips come under this class of poisonous weeds. Injurious weed seeds are frequently so nearly the size and color of the grain they adulterate as to make it practically impossible to separate them. Cockle in wheat and buckwheat may be given as examples.

Some weeds are beneficial. Sweet clover is a valuable bee food, a valuable soil improver, and a good forage plant. The roots of tanweed were used for tanning leather. The artichoke is used for food and hog pasture. The little white daisy is, pound for pound, nearly equal to timothy and is eaten readily by farm stock.

Farm Practices to Free a Farm of Weeds.—As in the case with insects, so with weeds, there are certain farm practices to be known and followed before we need resort to special means for the eradication of weeds. The first farm practice to be recommended to help in the control of weeds is a wide rotation of crops. Land that is continuously cropped with corn and oats becomes infested with a number of weeds that cannot survive in the meadow and pasture. This is especially true if the land be seeded to alfalfa which is cut a number of times each season (Fig. 116), or if the land be pastured with sheep which are weed eaters.

Again, if a piece of land is pastured for a long time it be-comes infested with weeds that survive in pastures but are easily killed in a cultivated field or in meadows used for the hay crop.

The next farm practice to be recommended, after the wide rotation of crops, is to be sure that the seed gets a good start in clean ground. This means that the ground should be disked and harrowed just before planting (Fig. 117), that the seed must not be put in when the ground is too cold or too wet or too dry. It also means that none but strong, large seed should be planted.

Says Dr. Bailey: * "Weeds are plants not wanted. They are of two general kinds—those that inhabit waste or unoccupied places, and those that invade crop lands. . . . All this sounds simple but it is a fact that we really do not know just why some weeds follow certain crops or how they injure the crops. It is commonly advised that the farmer do this and do that to destroy weeds, always putting the emphasis on the word destroy, but while it may be useful to prevent wild carrot from seeding, it is much more to the point not to have wild carrot. Much of the current advice on the destruction of weeds is of small value, for the farmer has little time or opportunity to hunt out the different species and then laboriously to prevent them from seeding or to spud them out. The fundamental thing is to apprehend the fact that certain weeds follow certain crops and certain methods of farming. Crop management, therefore, necessarily involves weed management. Some of the fundamental means of preventing weeds are good rotation courses; clean tillage; cleaning up waste places in which weeds breed; care in the choice of clean seeds and alertness to recognize new weeds when they begin to invade the neighborhood. This means that the farmer should endeavor to determine why he is possessed of certain weeds; this discovered he can then begin to treat the question rationally."

The following is given as a typical treatment of one weed, the treatment of which is also applicable to other similar weeds.

The Horse Nettle (Solanum Carolinense).—" Those who have held that perennials cannot be acclimated will find an excellent exception in horse nettle. Darlington in his ` Fiore Cestrica' makes the statement that horse nettle was introduced by Humphrey Marshall into his botanical garden at Marshall-town. The weed is still spreading. It now occurs from Connecticut, through New Jersey, New York, Pennsylvania, along the Atlantic coast to Florida, and west to Texas and Nebraska. It seems to be a native of the southeastern part of the United States."—Iowa Bulletin No. 42.

Methods of Propagation.—Horse nettle has two methods of propagation. One is by seeds and the other is by perennial roots. This makes it as difficult to eradicate as the Canadian thistle. Ordinary cultivation has little effect in checking it, and often helps to spread it by scattering pieces of roots. Horse nettle is more or less troublesome in all soils and all crops. It is an exceedingly tenacious weed and often covers whole fields.

Methods of Extermination.—There are a number of ways of dealing with horse nettle, among which are : Smothering, clean cultivation or hoe crops, mowing to keep from going to seed; but none of these is effective unless the farmer has a fair chance and applies the remedy with tact, skill and efficient equipment.

Smothering.—This may best be done with rape, millet, cane, etc. In case any of these are tried the crop should be sown late. Before sowing, the ground should be fall plowed and then disked frequently during the spring. The seed of the smother crop should be strong and sown thick, but not so thick as to make weak, sickly plants. When the crop has attained a rank growth it may be pastured or mowed and the ground immediately plowed and again disked or given clean culture until another crop is planted. If the patch is small, tar paper may be used to smother the weed.

Clean Culture.—For this, fall plowing is necessary. The old adage, " One acre in August equals two plowed in September, and one in September equals two plowed in October," holds for the eradication of weeds. If the ground is washy a late cover crop may be used, but the ground may be disked a few times before the cover crop is planted. The cover crop must be plowed under as early in spring as the ground is dry enough, and after that the ground should be disked frequently until the hoe crop of corn, potatoes, soy beans, etc., is planted. Then the crop must be cultivated frequently with efficient cultivators, for which the surface and disk cultivators are excellent to alternate with the shovel cultivator. Even with the best of cultivation it may be necessary to pull the weeds once or twice. The crop should be removed early and the field plowed and disked if weeds appear above the ground.

Good Farming.—But these are the methods for the small patch and probably for the small farmer. For the infested farm of the larger farmer, good farming is the effective remedy. For this he must seek a rotation that will give him money—making crops which are inimical to the persistence of the horse nettle. Perhaps nothing better can be suggested than alfalfa followed by corn or potatoes, and these in turn followed by oats and peas cut for hay and the ground again seeded to alfalfa. The alfalfa is cut three or four times in a summer.

Another part of good farming is the securing each season of clean seeds, another is the attention to fence rows and corners to see that few if any plants go to seed there, and yet another farm practice is the seeing to it that weed seed is not brought on to the farm from neighboring places. This often requires that a man become a crank to see that the State laws for the mowing of weeds along the road-side are enforced. Many weed seeds are scattered in manure and to prevent this it may be necessary to compost the manure. To prevent too heavy loss for the compost it may be necessary to mix with it land plaster or a calcium phosphate ground rock.

Other Weeds.—It will readily be seen that what has been said for the extermination of horse nettle applies to the extermination of the European bind weed, commonly called Morning Glory (Convolvulus arvensis), and Canadian thistle, which, like the horse nettle, multiply by both seed and rootstock. The bind weed is easier in one way, for into the rotation may be introduced pasturing, especially with sheep, following the alfalfa.

Exercises.—If the pupils did not learn of the poisonous plants in their nature study, then it is in order for a series of lessons on the poisonous plants, to be given as part of the work in agriculture. Among the poisonous plants we find poison ivy (Rhus radicans), poison sumac (Rhus vernix), water hemlock, corn cockle, broad-leafed laurel, and black cherry. Certainly, children should be taught how to identify each of these plants, how the plant poisons and hence how we may avoid its injuries, and how best to eradicate the plant. Poison ivy, for example, is easily identified by its three leaves, while the five-leafed ivy does not poison, hence, while we may use the five-leafed ivy for decorations, we must fight the three-leafed ivy wherever found. The three-leafed ivy poisons by means of an oil which is thrown from or secreted by any part of the plant. Men have been very seriously poisoned by pulling out the roots while plowing. The plant should be handled with gloves and should be hoed or mowed by persons not easily poisoned.

The ability to analyze a sample of seed so as to tell its purity is a valuable accomplishment for any farm boy. Teachers may use the same plates which we use for soil study to analyze seeds. A sample of one hundred or two hundred seeds may be poured on to a plate for each pupil. Then each pupil may be required to separate one hundred seeds into the grain being examined, one or two known weeds, and one sample of unknown impurities—broken seeds, unknown weed seeds, dirt, etc. By taking the averages for a class, a school learns very accurately the per cent of weed seed in a sample. The farmers should be able to get their clover and alfalfa seeds analyzed by their schools free of cost and in an accurate, reliable way. Interesting problems in arithmetic follow by figuring on the fraction, the percentage, the ratio of good seed to certain kinds of weeds, the value of the seed, the relative value of different dealers' samples, the number of weed seeds that would be sown per square rod, and the relative loss on the sample.



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