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| Protection of Crops |
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| Certain preventive measures can be adopted to protect crops from weeds, insects, mites, rodents and fungi. |
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| They are: |
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 Use of resistant varieties |
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 Optimum time of sowing the crops |
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 Crop rotation and cropping system |
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 Clean cultivation |
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 Summer ploughing |
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| Rabi crops are more susceptible to insects and pests as against kharif crops as warm and humid climate is congenial for infestation. |
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| If field crops are infested with insects and pests, diseases or weeds, insect pest control, disease control and weed control measures have to adopted. |
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| If insect pests attack the plant by cutting and destroying the root an insecticide like chloropyrophos is mixed in the soil to control it. |
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| If insect pests attack the plant by cutting the stem and leaves and it is a boring type of insect, it can be controlled by dusting or spraying contact insecticides like malathion, lindane and thiodax. |
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| If the insect pests suck the sap from various parts of the plant, it can be controlled by spraying systemic insecticides like dimethoate and metasystox. |
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| Plants often get infested with disease causing pathogens. The entire crop can be destroyed if they are not controlled in time. |
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| Pathogens are transmitted by: |
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 seed and soil |
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 water |
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 air |
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| Seed soil and water borne diseases mostly attack roots and plant stem. Air borne diseases attack all aerial parts of the plant i.e. leaf, flower and fruit. Seed and soil borne diseases can be controlled by treating the seed and soil. Air borne diseases can be controlled by treating the infested parts with fungicide spray. |
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| Weeds are unwanted plants that grow in the fields where crops grow. The growth of weeds in fields has an adverse affect on crops because they compete with the crops for space, light, nutrients and water. The yield becomes poor and so also the quality of the crop. The weed could be another crop plant or a plant of another variety of the same crop. So if a mustard plant grows in a wheat field it has grown out of place and so is considered to be a weed. Often weeds harbour many insects, pest and diseases. Warm and humid climate being more congenial for the growth of weeds, they are more during the Kharif season than the Rabi crop. |
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| Based on the structure of the leaf, weeds are classified into narrow-leaf and broad-leaf. The following are some of the weeds of the Kharif season and the Rabi season. |
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| Kharif Season |
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| Narrow Leaf |
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| Example: 1) Nutgrass (motha), |
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| 2) Wild Sorghum (Wild jowar) |
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| Broad Leaf |
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| Example: 1) Amaranthus (chaulai) |
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| 2) Trianthema (Saathi) |
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| Rabi Season |
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| Narrow Leaf |
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| Example: 1) Phalaris (Mandoori), |
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| 2) Wild oat (Jangali jaii) |
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| Broad Leaf |
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| Example: 1) Chenopodium (Bathua) |
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| 2) Convolvulus (Hirankhwci) |
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| During Kharif season, short duration maize and millets, short statured groundnut and slow growing pigeon pea crops are more prone to weeds. |
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| Mechanical Method |
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| Removal of weeds by mechanical methods are: |
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 pulling them out (uprooting) with hand |
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 removal by using a hoe or trowel |
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 interculture |
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 ploughing |
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 burning and |
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 flooding |
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| Cultural Method |
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| Cultural methods of controlling weeds include: |
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 proper seed bed preparation |
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 timely sowing of crops |
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 intercropping and |
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 crop rotation |
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| Chemical Method |
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| Spraying of special chemicals called weedicides or herbicides is a chemical method. |
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| Example: atrazine; 2, 4-D, fluchloralin; isoproturon |
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| Biological Method |
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| The biological method involves the use of some appropriate insects or some other organisms on the crop field having weeds. They selectively destroy the weed plants but do not harm the crop plants. |
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| Example: Cochneal insects are used to eradicate opuntia (a weed, commonly called prickly pear). Aquatic weeds are controlled by grass carp (a kind of fish). |
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