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11 Cards in this Set
- Front
- Back
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Why is weed control desirable in terms of increasing crop yield and minimizing costs?
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reduce competition for light, water and minerals (more yield)
replace manual/mechanical labor eliminate weeds which contain toxins less cover for other pests including diseases and insects |
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What are some terms for herbicide use? (many types of uses)
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contact- kill only plant parts to which herbicide was applied
systemic- absorbed by roots or above ground parts and moved to distant tissues eradicant- completely eliminate vegetation selective- kill or stunt weeds without harm to crop |
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What are the terms for timing of application of herbicides?
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Preplant- before crop is planted for control of annual weeds
preemergence- before crop or weeds emerge postemergence - self explanatory |
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What are the terms for how you apply the herbicides?
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band- continuous over a restricted area
broadcast- uniformly over entire area spot treatments- small areas directed sprays- applied to selected weeds or to the soil to avoid contact with the crop |
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What are some factors which contribute to herbicide effectiveness?
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1. weed type
2. soil condition- its type, moisture, and herbicide absorption 3. rainfall or irrigation- water usually required for activation 4. time of application- time of growth of weed/crop and when the herbicide is effective during which stage |
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What are the different types of herbicide placements and note any disadvantages?
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Preplant incorporation- volatile and photolabile herbicides incorporated before planting
- most effective at dry weather, moisture insures activation- - EXTRA TIME AND LABOR IN INCORPORATION Preemergence (PRE) applied to soil surface - activated by rain - RELIANCE ON WATER Postemergence (POST) applied to germinated weeds |
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What's the difference between a dessicant and defoliant?
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Dessicant- accelerate leaf fall
Defoliant- cause foilage to lose water and leaves remain on plants |
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Which of the dessicant/defoliant must be applied early?
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Defoliants must be applied early
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What are the advantages between dessicants and defoliants?
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Dessicants- can apply later, functions longer, contributes to cotton seed quality
Defoliant- earlier harvesting, higher grade of cotton because fewer leaves remain to clog the mechanical picker, increase exposure to sun and air |
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What are the benefits from using plant growth regulators?
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Better quality foods, you get fruits and vegetables year round (despite "out of season"), and lower food cost (no need for manual labor)
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What are the six types of PGRs and an example of each? (especially auxin and gibberellins)
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auxins- indoleacetic acid, enhance elongation in shoot cells- loosening of cell walls
Gibberillins- stimulate cell division/elongation - GA3 most used Cytokinins- prolong storage life- induce cell division- derivatives of adenine Ethylene- induce ripening Inhibitors- inhibit growth and germination- prevent sprouting of stored crops (potatoes) - benzoic acid Growth retardants |
