Environmental Science 1021F/G Lecture Notes - Companion Planting, Pyrethrum, Rodenticide
17 Aug 2012
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Document Summary
Pesticides = generic term for all unwanted organisms. Pest - subjective; only a weed/disturbance if unwanted. Spiel weed is killed in many areas, and grown for food in others. Insecticides - block reproduction, breathing, nervous system: herbicides - block photosynthesis, fungicides, rodenticides. Used to control agriculture & negative influences on agriculture. Crop rotation, minimizing input of pest, companion cropping to deter pests. Based on natural relationship of plants: many plants have defense mechanisms to keep away pests, we"re now coming back to there methods. Poisons, heavy metals: detrimental to human health, still present in soils today. Nicotine sulphate (in tobacco plant), pyrethrum (marigold plant: natural pesticide extracts still bottled and sold, marigolds are used in companion planting. 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.
