Environmental Issues Relating to Our Food: Lecture Notes.docx

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Environmental Science
Course Code
Environmental Science 1021F/G
Geoff Stewart

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Food III Pests and Pesticides Pesticides = generic term for all unwanted organisms Pest - subjective; only a weed/disturbance if unwanted Eg. Spiel weed is killed in many areas, and grown for food in others Types of Pesticides 1. Insecticides - block reproduction, breathing, nervous system 2. Herbicides - block photosynthesis 3. Fungicides 4. Rodenticides  Used to control agriculture & negative influences on agriculture  Began w/ herbicides mostly Before pesticides:  Crop rotation, minimizing input of pest, companion cropping to deter pests  Based on natural relationship of plants o Many plants have defense mechanisms to keep away pests o We're now coming back to there methods 1st generation pesticides  Poisons, heavy metals o Detrimental to human health o Still present in soils today  Nicotine sulphate (in tobacco plant), pyrethrum (marigold plant) o Natural pesticide extracts still bottled and sold o Marigolds are used in companion planting 2nd generation  Away from natural pesticides  Synthetic pesticides (i.e. DDT)  Began w/ broad spectrum (kills everything or many things not necessarily pests - Roundup), moving toward narrow spectrum (specialized - grasses, broad leafed plants) both in use and future research  Discovery that non-biodegradable, broad spectrum pesticides are harmful  Biodegradable pesticides w/ no long-term effects on soils, detritivores, plants, insects, water, ecosystems now found to be ideal The Case for Pesticides  Protect h
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