Lecture 01. Introduction

Lecture 01. Introduction - Introduction to Weed Science PLS...

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Unformatted text preview: Introduction to Weed Science PLS 176 Winter 2010 Naturalized Species Non-native, introduced on purpose or accidentally by man to an area. Has naturalized (overcame survival and reproduction barriers). Invasive Plant Species Non-native to the ecosystem under consideration, but naturalized; can expand their density and/or spatial extent. Some cause or can cause economic or environmental harm or harm to human or animal health. Beck et al. 2008. Inv. Plant Sci. Manage 1:414-421 Weed A subset of plant species, not necessarily NIS, that get placed on a list (often designated by law, e.g. state or federal noxious weed list) based on professional consensus that the species represents some problem for people. A Weed? • • • • • Growing in an undesirable location Competitive and aggressive Persistent, difficult to control Appears without being sown Unsightly Radosevich et al. 1997 Thus... Weeds are defined by human values rather than biological characteristics. are not inherently evil plants...they just are regular plants with adaptations allowing them to interfere with human activity. Radosevich et al. 1997 Beneficial Effects Food sources Medicinal Erosion control Insect trap Pollution control; bioremediation Adverse Impacts of Weeds Crop yield and quality Increased production costs Human and animal health Land value Recreation value Harbor pests Adapt from C. Mallory-Smith 2002 Adverse Impacts of Weeds Impact on natural ecosystems Invasive Transformers: • Alter ecosystems; habitat destruction • Reduce plant & animal diversity • Promote flooding or erosion • Alter fire frequency Adapt from C. Mallory-Smith 2002 Losses to Weeds Cause major production limitation that threatens world food and fiber supply Adapt from C. Mallory-Smith Estimated impact of weeds in US economy Impact on Agriculture = 75% of total impact Bridges, 1994. Weed Technol. 8:392-395 Weed control Worldwide more labor is expended on weed control than any other human endeavor Most hand weeding is performed by women and children Adapt from C. Mallory-Smith Weed Science • 1940’s New discipline based on herbicides • 2004 Diverse scientific field • Weed Biology • Ecology, Ecophysiology • Molecular biology & genetics Adapt from C. Mallory-Smith Integrated Weed Management • Part of Vegetation Management to modify the environment against: ecological succession natural evolutionary pressure • Many little hammers…diversity Liebman & Gallant, 1997. • Long-term; contemplates societal goals Non-chemical weed control secondary tillage: weed control GPS (Global Positioning Systems)/GIS (Geographic Information Systems) Adapt from C. Mallory-Smith 2002 Weed Biology and Ecology Biological Control Cinnabar moth (Tyria jacobaeae) Tansy ragwort (Senecio jacobaea) Herbicide Resistance Adapt from C. Mallory-Smith 2002 Environmental Impacts of Herbicides World population ~6.8 billion and counting 3 per second 260,000 per day 95 million per year http://www.poodwaddle.com/worldclock.swf Adapt from C. Mallory-Smith Exponential growth;growth predicted Population billion, 2050 leveling-off at 8-12 Food supply We need to triplicate food by 2050 Must come from the farmland we already have in order to save the planet’s wildlands Food security has helped bring fertility rates 80 % of the way to stability Adapt from C. Mallory-Smith 2002 “You can’t build peace on empty stomachs“ Lord John Boyd Orr, Nobel Peace laureate Adapt from C. Mallory-Smith 2002 We cannot afford the loss of food production caused by weeds We must preserve our environment and ecosystems Adapt from C. Mallory-Smith 2002 ...
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This note was uploaded on 03/05/2010 for the course PLS 176 taught by Professor Fischer during the Winter '10 term at UC Davis.

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