An integrated weed management approach to land management combines the use of complementary weed control methods such as grazing, herbicide application, land fallowing, and biological control.
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INTEGRATED WEED MANAGEMENT ( IWM ) 1 Department of Agronomy Bahauddin Zakariya University Multan
Introduction: What is a weed? There are numerous definitions of a weed, including: a plant out of place and not intentionally sown a plant growing where it is not wanted a plant whose virtues have not yet been discovered. ( R.W.Emerson ) plants that are competitive, persistent, pernicious, and interfere negatively with human activity (Ross, et. al.) 2
Integrated Weed Management Definition : “An integrated weed management approach to land management combines the use of complementary weed control methods such as grazing, herbicide application, land fallowing, and biological control .” 3
Importance of W eeds Management Those plants that interfere with human activity in crop and non-crop areas are considered weeds . Weeds compete with crops for soil nutrients, water and light; they host insects and plant pathogens harmful to crop plants, and their root exudates and/or leaf leachates may be toxic to crop plants. Weeds also hinder crop harvest and increase the costs of such operations . In addition, at harvest, weed seeds often contaminate the crop produce. Thus, the presence of weeds in crop areas reduces the efficiency of inputs such as fertilizer and irrigation water, enhances the density of other pest organisms, and finally severely reduces crop yield and quality. ( Labrada and Parker 1999 ) 4
Crop-weed Compitition 5 Light Water Nutrients Space
Integrated weed management Indirect Methods Preventive Methods Cultural Methods and ecological Methods Direct Methods Manual Methods Mechanical Methods Biological control Chemical control 6
A) Indirect Methods 1) Preventive Methods: Use of clean seed Use of clean farm equipments Clean leaves, watercourses and irrigation canals Control grazing of livestock Ensure that farmyard manure and other soil materials are free of weed Prevent the formation of weed seeds or vegetative progules Act collectively against wind-borne weeds/weed seeds Adopt specific measures when harvesting weed-infested crops Legislation 7
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2) Cultural Methods : Tillage Preparatory Tillage Seed Preparation Cultivation/harrowing/hoeing/ earthing up Rotation Allelopathy Flooding and drainage Methods of Planting Planting density Variety Mulching Planting time Farm Management Practices 9
B) Direct Methods Manual Methods Manual methods includes pulling of weeds by hand, cutting them with a sickle, hoeing with hand tools and burying the weeds under soil or water with the feet. 10
2) Mechanical Methods These methods involve the use of implements such as bar harrows, weeders , and cultivators driven by an animal or engine. 11
3) Biological control Biological weed control involves using living organisms, such as insects, nematodes, bacteria, or fungi, to reduce weed populations. In nature, plants are controlled biologically by naturally occurring organisms. Plants become pests - and are labeled "weeds" - when they run rampant because their natural enemies become ineffective or are nonexistent . 12
Examples of Biological weeds control 13
Examples of Biological weeds control 14
Examples of Biological weeds control 15
4) Chemical control Definition: Herbicides are chemicals that kill or alter the normal growth of weeds. They can be divided into two main groups: selective and nonselective. Selective herbicides are those that control the target weed(s) without damaging desirable turfgrass species. Nonselective herbicides kill all vegetation (including turfgrasses ) and are used in lawn renovation or on weeds not controlled by selective herbicides. 16