Term
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Definition
| Much cheaper: $1942/acre for manual control vs 234/acre for pesticide usage |
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Term
| Herbicide History (phase 1) |
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Definition
-Roman Empire, use of inorganic chemicals, salt, smelter sludge, ash
- no selectivity |
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Term
| Herbicide History (phase 2) |
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Definition
Inorganic Chemicals (industrial bi-products): sodium arsenate and sodium chlorate, no selectivity and residue problems
-early 1900s, first organics from the petroleum and coal industry, dinitrophenols (control dicots in monocots, (still human toxic)
-bordeaux mixture (copper sulfate and slaked lime), more toxic to mustards than cereals |
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Term
| Herbicide History (phase 3) |
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Definition
coming of age:
-1940's: auxinics, 2,4-D and MCPA (selective, low toxicity and selective)
-1950s: big interest in developing new P's, paraquat and ureas (less persistance)
-1960's: the glory days, pyridines and triazines (mostly soil active and moderate persistence
-1970's foliar, systemic herbicides (glyphosate)
-1980's, very low rate herbicides (sulfonylureas)
-1990's, markets saturated, more ACCase and ALS inhibitors
-phase 3.2 biological origin, glufosinate and pyrethroids |
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Term
| Herbicide History (phase 4) |
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Definition
Biotechnology approach
-conventional breeding, mutagenesis, gene transfer
-try to make non-selective herbicides into selective |
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Term
| Herbicide Discovery Time Crunch |
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Definition
-marketed in 7 years
-break even in 15
-patent lasts 15-20 years, therefore only have 5 years to break even |
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Term
| Herbicide Discovery Process |
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Definition
is a need to be quicker
- High throughput screening: microammounts of chemical in vitro using Lemna minor, 100ks screened each year, need more more
- Natural compunds, can give direction
- Combinatorial Synthesis: many variants made at once, 3 points of diveristy and 30 building blocks = 27k (tagged to recall)
- Functional Genomics: ID key process in plant, isolate enzymatic function and target screening at this |
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Term
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Definition
By the PMRA
-Human Health (risk = exposure*toxicity)
-Environmental Risk (persistence, toxicity to target)
-Efficacy (merit and claims, lowest effective dose)
------> Manufacturer pays |
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Term
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Definition
-absorption depends on interception
-Retention is required (helped by surfactant, can bead off because droplets)
-trichomes can also be in way |
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Term
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Definition
| active ingredient + formulant, goals of this: retain activity over time, ease of use, increase safety, redice foaming |
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Term
| Herbicide Movement in Plant |
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Definition
-Apoplastic (through xlyem, must have to eventually get into symplasm)
-Symplastic (thorugh plhloem) presence of carboxyllic group (weak acid) |
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Term
| 4 Methods of Phloem Translocation |
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Definition
1) Simple Diffusion: H partitions into lipid membrane, more lipophillic enter easier
2)Carrier method: H actively shuttles across
3)Intermediate Diffusion: H move in slowly via plasmalemma
4)Weak acid accumulation: un-dissociated enter |
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Term
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Definition
1)Toxification: pro-herbicide into a herbicide eg; 2,4-DB and b-oxidation
2)Conversion: of herbicide (active form) into metabolite (inactive form)
3)Conjugation: molecule added to H to ease its sequestration
4)Sequestration: H excluded from area it is residing |
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Term
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Definition
| Protect crop by improving selectivity of H |
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Term
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Definition
competitive and non-competitive inhibition
-build up of intermediate or starved of product |
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Term
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Definition
| Herbicide out competes PQ at D1 binding site, causes engergy build up, leads to ROS formation ---> lipid peroxidation and cell lyse |
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Term
Triazines
3 nitrogen in ring in triangle |
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Definition
control boradleaves and some grass
-absorbed by roots and leaves, xylem mobile, safe on corn
-eg; atrazine |
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Term
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Definition
-Metribuzin
control boradleaves and some grass
-used in soy, potatoes, tomatoes
-not safe for corn
-strictly pre-emergence |
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Term
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Definition
Phenylureas
control boradleaves and some grass
-eg linuron in carrots, corn, soy |
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Term
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Definition
-Bromoxynil
control boradleaves safe on grass
- eg buctril M
- contact only |
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Term
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Definition
-Bentazon
control boradleaves safe on grass
- eg Basagram
- contact only |
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Term
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Definition
-Bipyridilliums (paraquat and diquat)
PS1 inhibitor
used in industrial sites
-diquat used as dessicant
-inhibits FD to NAP-, gets reduced, as oxidaized makes ROS
- kills monocots and diquats |
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Term
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Definition
-Protox inhibitors
-inhibit chlorophyll synthesis
-diphenyl ethers = fomesafen
[image]
-accumulation of Protoporphyrin 9, inhibit enzyme that makes it, protoporphyrinogen 9 builds up and leaks out and makes Protoporphyrin 9 which reacts wiht light and O2 to make ROS |
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