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Weed

2007 Schools Wikipedia Selection. Related subjects: Plants

   A common weed flower
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   A common weed flower

   The notion of "weed" is almost entirely in the eye of the beholder. A
   weed in one situation might be a wildflower in another. For example,
   dandelions are widely viewed as weeds, but some consider them
   attractive flowers. Some weeds are edible, and their leaves and roots
   may be utilized for food or herbal medicine. It is typically necessary
   for a plant to grow easily and spread persistently to be considered a
   weed, because plants which need to be carefully nurtured are easily
   removed.

Weed control

   In order to reduce weed growth, many weed control strategies have been
   developed. The most basic is ploughing, which cuts the roots of annual
   weeds. Today, chemical weed killers known as herbicides are widely
   used. Modern herbicides such as glyphosate are designed to leave no
   harmful residue in the soil, although the surfactants can be
   detrimental to watercourses. But these often have a bad effect on
   wildlife as farmers overuse it and it can get in water supply. In
   domestic gardens, methods of weed control include covering an area of
   ground with several layers of wet newspaper or a black plastic sheet
   for several weeks. In the case of using wet newspaper, the multiple
   layers prevent light from reaching all plants beneath, which kills
   them. Saturating the newspaper with water daily speeds the
   decomposition of the dead plants. Any weed seeds that start to sprout
   because of the water will also be deprived of sunlight, be killed, and
   decompose. After several weeks, all germinating weed seeds present in
   the ground should be dead. Then the newspaper can be removed and the
   ground can be planted. The decomposed plants will help fertilize the
   plants or seeds planted later. In the case of using the black plastic
   sheet, the greenhouse effect is used to kill the plants beneath the
   sheet. A 5-10 cm layer of wood chip mulch on the ground will also
   prevent most weeds from sprouting. Also, gravel can be spread over the
   ground as an inorganic mulch.

   In agriculture, irrigation is sometimes used as a weed control measure
   such as in the case of paddy fields.

Some Examples

   Here is a partial list of plants that are commonly considered weeds.
     * Broadleaf plantain
     * Burdock
     * Cannabis
     * Creeping Charlie
     * Dandelion
     * Kudzu
     * Leafy Spurge
     * Milk Thistle
     * Ragweed
     * Red sorrel
     * Sumac
     * Wild Carrot
     * Winter Cress

   Retrieved from " http://en.wikipedia.org/wiki/Weed"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
