A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals. Examples are prickly lettuce (lactuca scariola) and sow thistle (sonchus species) that serve as hosts for downy mildew; Universities and agricultural colleges teach courses in weed control, and industry provides the necessary technology. Any method of weed control that minimizes tillage tends to conserve soil structure and maintain fertility. Mulching, which is used to suppress weeds in a home garden, is not feasible on large farms. Some can be helpful by breaking up or temporarily covering the soil, nourishing pollinators and even people. And the costly requirement of livestock or fowl for the biological grazing methods. They may lower values of animal products, as in the cases of cockleburs (xanthium species) in wool; · while some weeds are a nuisance, some feed people and pollinators. All of those methods have drawbacks: Herbicide chemicals sprayed on a roadside to eliminate unsightly weeds that constitute a fire or traffic hazard are not proper for use on cropland. Tillage, still the most widely used method of row-crop weed control, has been greatly improved by development of precision seeding and close preadjustment of tiller tools, allowing the passage of weed knives within an inch or less of the young crop plants. Such methods as crop rotation, use of smother crops, use of weedfree seed, mulching and covering, and cleaning of machinery to prevent spread of weed seeds are also classified as mechanical. Not all weeds need to be eradicated. Some unwanted plants later were found to have virtues not originally suspected and so were removed from the category of weeds and taken under cultivation. There is the arduous, painful nature of hand weeding; Weeds interfere with a variety of human activities, and many methods have been developed to suppress or eliminate them. Additionally, tillage tools can spread perennial weeds rapidly, bringing about rapid infestation of whole fields. Learn about the biological characteristics, evolution, and cultural significance of weeds, as well as the various ways to control them in agriculture and horticulture. And saltbrush (atriplex species) and russian thistle, in which curly top virus overwinters, to be carried to sugar beets by leafhoppers. Contrary to the principles of ecology, farmers throughout the world grow the major food, fibre, and forage crops in a monoculture because experience has shown that the highly improved modern crop species give their highest yield under this system. The category of weeds thus is ever changing, and the term is a relative one. When the area is converted to a golf course or a public park, they become an actual nuisance. Weed, general term for any plant growing where it is not wanted. The principal virtue of cultivation of row crops is the control of weeds. For thousands of years, from the egyptian culture to the renaissance, those simple methods were used. From hand pulling, humans devised simple tools such as the spud, the knife, and the hoe to eliminate weeds. But as the old saying goes, “one man’s trash is another man’s treasure,” and there are many “ weeds ” that are, in fact, completely edible. Are you a student? Many weeds are hosts of insect pests, and a number are invasive species. Get britannica premium for only 24. 95 - a 67% discount! Many weeds are hosts of plant disease organisms. Not everyone agrees on which plants are weeds , or what to do about them. The slow, fuel-consuming nature of burning; The first efforts to turn away from simple hand methods and mechanize the arduous task of weed control began in 17th-century england. · a complete guide to the most common weeds you can find in your garden landscape. The repetitious and often harmful nature of clean tillage with machinery; These methods vary with the nature of the weed itself, the means at hand for disposal, and the relation of the method to the environment. What is a weed ? See full list on britannica. com · the first step to removing weeds from your lawn and garden is identification. Learn about 20 common types of weeds and how to treat them. Weed control, in any event, has become a highly specialized activity. Sharp-edged grasses are nominal nuisances in a cow pasture; · basically, a weed is nothing more than a plant growing where it is not wanted, the classic example being dandelions in the lawn. In addition to tillage, other mechanical methods of weed control involve burning, grazing, and the use of ducks or geese in certain crops (in cotton and mint especially). Other cultivated plants, when transplanted to new climates, escaped cultivation and became weeds or invasive species. Mechanical weed control began when humans first pulled weeds from their cereal crops and attempted to grow single plant species, free from all plant competition. Despite these improvements it is known that weed knives injure crop roots, especially late in the tillage season. Poison oak (toxicodendron diversilobum) is rather a pleasant shrub on a sunny hillside in the open country; Tall weeds on roadsides presumably were not problematic prior to the invention of the automobile. In agriculture, weed control is essential for maintaining high levels of crop production. However, with cars and increasing numbers of drivers on roads, tall weeds became dangerous, potentially obscuring drivers’ visibility, particularly at intersections. They may cause injuries, as with lodging of foxtails (alopecurus species) in horses’ mouths; Weeds compete with crop plants for water, light, and nutrients. Ever since humans first attempted the cultivation of plants, they have had to fight the invasion by weeds into areas chosen for crops. Plants with characteristics that make them hazardous, aesthetically unappealing, difficult to control in managed environments, or otherwise unwanted in farm land, orchards, gardens, lawns, parks, recreational spaces, residential and industrial areas, may all be co. The many reasons for controlling weeds become more complex with the increasing development of technology. From cute to carnivorous In a camp ground it is a definite health hazard. Usually for financial and ecological reasons, methods used on a golf course or a public park cannot be applied on rangeland or in the forest. That was the start of monoculture, a method that since has come to dominate agriculture. Weeds of rangelands and pastures may be unpalatable to animals, or even poisonous; Since then there has been continuous improvement of agricultural tools used to destroy weeds and of cultural methods employed to minimize weed growth. Plants become weeds as a function of time and place. Wild mustards (brassica species) that host clubroot of cabbage; They may add to the burden of animal care, as when horses graze in sticky tarweeds (madia species). Such examples could be given ad infinitum to cover every aspect of agriculture, forestry, highway, waterway and public land management, arboretum, park and golf-course care, and home landscape maintenance.
