Weeds in Wheat Crop

S.#

Scientific name

Family

English name

Common name

1.

Amaranthus viridis L.

Amaranthaceae

Pigweed

Jangli cholai

2.

Anagallis arvensis L.

Primulaceae

Blue Pimpernel

Billi booti

3.

Asphodelus tenuifolius Cav.

Asphodeliaceae

Wild onion

Piazi, bhokat

4.

Avena fetua L.

Poaceae

Wild oat

Jangli jai, Javdri

5.

Carthamus oxycantha (L.) G. Don

Asteraceae

Wild safflower

Pohli, kandiari

6.

Chenopodium album L.

Chenopodiaceae

Goose foot

Bathu,bathwa

7.

Chenopodium murale L.

Chenopodiaceae

Fat hen

Karund

8.

Cichorium intybus L.

Asteraceae

Blue daisy

Kasni

9.

Cirsium arvense (L.) Scop

Asteraceae

Creeping thistle

Kandyari, Leh

10.

Convolvulus arvensis L.

Convolvulaceae

Field binweed

Lehli, Hirankhuri

11.

Coronopus didymus (L.)Smith.

Brassicaceae

Swine cress

Jangli halon

12.

Cynodon dactylon (L.)

Poaceae

Bermuda Grass

Dub, Khabbal

13.

Euphorbia helioscopia L.

Euphorbiaceae

Sun spurge

Dudhi

14.

Fumaria indica (Hausskn) Pugsley

Fumariaceae

Fumitory

Shahtra, pitpapra

15.

Galium aparine L.

Rubiaceae

Bedstraw

Warribooti

16.

Lathyrus aphaca L.

Papiolanaceae

Crow pea

Dokanni

17.

Lathyrus sativus L.

Papiolanaceae

Grass pea

Chraal, kasseri

18.

Lepidium sativum L.

Brassicaceae

Garden cress

Halon

19.

Malva parviflora L.

Malvaceae al

Dwarf mallow

Sonchal

20.

Medicago polymorpha L.

Papiolanaceae

Bur clover

Maina

21.

Melilotus alba Desr.

Papiolanaceae

White sweet clover

Sufaid senji

22.

Melilotus indica (L.) All.

Papiolanaceae

Yellow sweet clover

Zard senji

23.

Phalaris minor Retz.

Poaceae

Bird’s seed grass

Dumbi sittee

24.

Polygonum plebejum R. Br.

Polygonaceae

Prostrate knotweed

Dranak, hazardani

25.

Polypogon monspeliensis (L.) Desf.

Poaceae

Rabbit foot grass

Lomar ghas

26.

Rumex dentatus L.

Polygonaceae

Broadleaf dock

Jangli palak

27.

Saponaria vaccaria L.

Caryophyllaceae

Soapwort

Takla

28.

Sisymbrio irio L.

Brassicaceae

London rocket

Khoob kalan

29.

Sonchus asper (L.) Hill

Asteraceae

Spiny sowthisle

Kandiali, dodhak

30.

Spergula arvensis L.

Spergulaceae

Corn spurry

Kalri booti

31.

Stelleria media (L.) Vill.

Caryophyllaceae

Common chickweed

Stel Phullan booti,

32.

Vicia sativa L.

Papiolanaceae

Common vetch

Revari, Choti phali

Economic Importance of Weeds

Economic Importance of Weeds

Weeds have certain results in agriculture, which might be mostly in the form of different damaging results however someway there are also some really useful effects.

Direct Losses by means of weeds

Weeds motive relief in crop yield through competition for mild, nutrient, water and space. They too can scale back the yield of crop in the course of the release of toxic elements or exudates which inhibit crop expansion. This is named allelopathy. Uncontrolled weed infestation can lead to 95% yield loss in cassava, 40% in maize and 53% in cowpea, soybean and pigeon pea.

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  1. Weeds can scale back the quality of harvested agricultural merchandise.
  2. Weeds intrude with harvest operations and build up the cost of harvesting in each small holder and massive scale farms.
    four. Weeds would possibly poison animals e.g. Amaranthus spp can adversely affect cattle because of the top nitrate content material of the shoots.
  3. The cost of controlling weeds is high.
  4. The presence of weeds can impede water flow in irrigation canals.
  5. The presence of weeds in lakes and reservoir can building up lack of water via transpiration.
    Indirect Losses led to by weeds
  6. Weeds function change hosts to many plant illnesses and animal pests e.g bugs, rodents, birds and many others that assault crops.
  7. The presence of weeds imposes a restrict on farm size.
    three. The presence of weeds can also scale back the economic worth of lakes by means of fighting or proscribing fishing actions.
    four. Weeds similar to Imperata cylindrica grow to be hearth hazards within the dry season during the savanna crops zone.
    Non Agricultural Losses
  8. Weeds impact health of people, stinging nettle can cause skin rashes and the vegetation of some different weeds can be associated with allergic reactions in humans
  9. Weeds impair visibility along roads and railway lines.
  10. Uncontrolled weed enlargement reduces the value of actual estates.
  11. In eventualities the place farmers rely on human labour for weeding, youngsters need to leave out college at peak of weeding periods. This reduces the standard of training that these children can get during their early years.

Beneficial Effects of Weeds

  1. Weeds supply a vegetative duvet that protects the soil surface in opposition to erosive motion of rain and wind.
  2. Weeds play an important section in nutrient recycling. Roots of weeds faucet nutrients from the decrease soil depths and go back these to the soil surface as clutter when the weeds shed their leaves or when all of the plant vegetation dies and decays.
    three. Weeds add organic matter to the soil each from the roots and from the above flooring portions.
    four. Many vegetation which can be designated weeds are used as potherbs e.g Talinum triangulare.
  3. Weeds are assets of insecticides e.g Chrysanthemum cinerariifolium which gives insecticide pyrethrum.
  4. Weeds provide meals and cover for animal. Wildlife in most cases will depend on weeds for survival as meals and safe haven.
  5. Weeds serve as the most important supply of genetic materials for crop improvement akin to breeding for resistance to pests and illnesses which might be made possible through genetic materials supplied via wild species of the crop plants.
  6. Weeds serve as hosts advisable bugs, and at the similar time provide nectar for bees.
  7. Many weeds lend a hand to enhance the landscape. e.g a just right flooring duvet of Cynodon dactylon beautifies the house.

Anatomical Differences Between Crop and Weed

The amount of spray retention by foliage after postemergence applications can affect selectivity. This selectivity is usually due to the crop plant’s having a waxy cuticle that repels the spray solution.Examples include onions, peas, cereal grains, Brassica vegetable crops, and conifers. Medium to high spray volumes usually provide better selectivity, and adding an adjuvant can decrease selectivity as a result of enhanced adhesion of the spray droplets. Anatomical Differences Between Crop and WeedDifferences in leaf shape, size, and orientation between weed and crop can provide some selectivity differences. This is most common for controlling dicot weeds in small grain crops (the grain leaves retain less herbicide because of shape, orientation, size, and granular epicuticular wax). Postemergence selectivity can be due to the growing point of the crop being protected from direct contact by the herbicide while the growing point of the weed is exposed. The best example is dicot weed control (growing point not well protected by emerging leaves) in small grains (growing point well protected by the whorls of emerging leaves). The herbicide must not have a high degree of phloem mobility for this selectivitymechanism to work. For more detail regarding the influence of plant morphology on herbicide absorption, see the review by Hess (1987).

Preemergence selectivity can be due to a difference in root morphology between the weed and the crop. Grass weeds usually have a fibrous root system, whereas dicot crops usually have a taproot system. Thus,growth inhibitor herbicides, such as trifluralin, applied to the soil come directly in contact with the growing root tips in grass weeds, but not with those of the deeper-rooted dicot crops. For this selectivity mechanism to be useful, the water solubility and soil binding characteristics of the herbicide must be such that movement isrestricted to the upper soil profile.
Morphology differences within stem tissue of grass plants can provide differences in selectivity. The growing point of many grass weeds (crabgrass and wild oat) are more exposed to herbicide-treated soil than wheat and barley where the growing point is protected inside the coleoptile.

Weed Classification

How many plants have these weedy characteristics? Relatively few, in fact. There are approximately 250,000 species of plants in the world, but only about 200 species are considered to be major weed problems (Holm, et al., 1977). In addition to this small number of species there are relatively few plant families that contain major weeds. Of the 300 plant families, 75 families comprise 75% of all flowering plants, and of these only 12 families comprise 68% of the world’s worst weeds (Holm,et al., 1977). Within these 12 families, just 3 families comprise 43% of the world’s worst weeds, with 37% being in the Poaceae (grass family) and Asteraceae (composite family). Most of the major families of weeds also contain members that are major crops, such as grains in the Poaceae, beans/peas in the Leguminosae, and vegetables in the Solanaceae and Brassicaceae, to name a few. Other families have few crop representatives but many weeds, such as the Asteraceae.Weeds Classification

The definition of a weed and the plant characteristics that contribute to its weediness are good to know. However, other factors such as habitat, growth form or seed type, and life cycle are important in identifying the most appropriate management practices for weeds in humans’ various plant-related activities and useful in determining specifically what weed is present in any given situation.

Classification on Habitat:

Habitat refers to whether the weed grows in a terrestrial or an aquatic environment. Weeds can be a problem in both habitats and can include epiphytic and parasitic types. Growth form or seed type can be used to classify plants in 3 categories. Gymnosperms, such as pines, have seeds not enclosed in an ovary. Examples include larch, fir, spruce, hemlock, Douglas fir, cedar, and redwood. Most gymnosperms are not considered to be weeds. Monocots, or flowering plants with one seed or cotyledon, generally have narrow leaves with parallel veins, but some monocots have large leaves with palmate-type veins, such as water hyacinth. Examples include lilies, irises, sedges, grasses, palms, orchids, cattails, sugar cane, and banana. Many of our most serious weed problems are monocots. An important distinction is that all grasses are monocots, but not all monocots are grasses. Dicots, or flowering plants with two seed leaves or cotyledons, include maple, oak, pigweed, common lambsquarters, and sunflower. Many of our most serious weed problems are dicots.

Classification on Life Cycle:

Life cycle refers to a plant’s life span, season of growth, and method of reproduction and determines the methods needed for management or eradication. Plants have been divided into three life cycle categories: annual, biennial,and perennial.

Annual Weeds:

Annual plants complete their life cycle (from seed to seed) in 1 year or less. Normally, they are considered easy to control. This is true for any one crop of weeds. However, because of an abundance of dormant seed and fast growth, annuals are very persistent and they actually cost more to control than perennial weeds. Most common weeds are annuals, and there are two types—winter and summer. Winter annuals germinate in autumn or winter and overwinter as a rosette, resume growth in early spring, and produce fruit and seed and die by midsummer. The seeds often lie dormant in the soil during the summer months. In this group, high soil temperature (125°F or above) has a tendency to cause seed dormancy—to inhibit seed germination. Examples include chickweed, downy brome, hairy cress, cheat, sheperds purse, field pennycress, corn cockle, cornflower, and henbit. These weeds are most troublesome in winter-growing crops such as winter wheat, winter oats, and winter barley.

Summer Annuals:

Summer annuals germinate in the spring, grow through the summer, and mature, form seed, and die by autumn. The seeds lie dormant in the soil until the next spring. Summer annuals include cockleburs, morningglories, pigweeds, common lambsquarters, common ragweed, crabgrasses, foxtails, and goosegrass. These weeds are troublesome in summer crops like corn, sorghum, soybeans, cotton, peanuts, tobacco, and many vegetables. A biennial plant lives more than 1 but less than 2 years. During the first phase of growth, the seedling usually develops vegetatively into a rosette. Following a cold period, vegetative growth resumes followed by floral initiation, fruit set, and death. There is confusion between the biennials and winter annuals because winter annuals normally live during 2 calendar years and during 2 seasons. Biennials generally grow later into the second season and tend to be larger plants. Examples include wild carrot, common mullein, bull thistle, wild lettuce, and common burdock. Several biennials are weed problems in minimum- or no-tillage systems and perennial crops.

Perennial Weeds:

A perennial plant lives for more than 2 years and is characterized by renewed growth year after year from the same root system. Most perennials reproduce by seed, and many are able to spread vegetatively. They are classified as simple, creeping, or woody.

Herbaceous Perennials:

Simple herbaceous perennials reproduce by seed and have no natural means of spreading vegetatively unless injured or cut; the cut pieces may produce new plants. For example, a dandelion or dock root cut in half longitudinally may produce two plants. The roots are usually fleshy and may grow very large. Examples include common dandelion, dock, buckhorn plantain, broadleaf plantain, and pokeweed.

Creeping herbaceous perennials:

Creeping herbaceous perennials reproduce by seed and by vegetative means, including creeping aboveground stems (stolons), creeping underground stems (rhizomes), or a spreading root system that contain buds. Examples include red sorrel, perennial sowthistle, quackgrass, bermudagrass, johnsongrass, and field bindweed. Some weeds maintain themselves and propagate by means of tubers, which are modified rhizomes adapted for food storage. Examples include purple and yellow nutsedge and Jerusalem artichoke.

In all cases, creeping perennials have tremendous vegetative reproductive capacity and are the most difficult weed problems to manage regardless of the tools used. Cultivators and plows often drag pieces about a field. Herbicides applied and mixed into the soil may reduce the chances of establishment of such pieces. Continuous and repeated cultivation, or mowing for 1 or 2 years, and use of persistent herbicides is often necessary for control. An eradication program requires the killing of seedlings as well as the dormant seeds in the soil.

Woody perennials:

Woody perennials are plants whose stems have secondary thickening and an annual growth increment. These plants can be weed problems in pastures and many perennial-cropping systems. Examples include poison ivy, wild brambles, and multiflora rose.