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16 Cards in this Set
- Front
- Back
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What is the mechanism of action of imidazolinones?
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Bind to enzyme ALS/AHAS inhibiting the synthesis of the AA valine, leucine and isoleucine causing decreased protein synthesis and cessation of plant growth
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What are the symptoms of Imis?
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susceptible weeds are severely stunted with shortened internodes; foliage of grass weeds may turn red to purplish in color
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What is the mobility of Imis?
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phloem mobile; rapidly absorbed by the foliage and roots, translocated to meristematic regions
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What are the 2 mechanisms of ALS resistance?
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1) enzyme mutation - less specific, possibility of cross resistance with sulfonylureas or urea
2) metabolism - more specific to an active ingredient by CP450 or multifunction oxidases (MFOs) |
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How can in furrow insecticides (organophosphates) distort corn when sprayed with an ALS compound like Imis and what is the effect on IR and IT corn?
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Organophosphates reduce MFO activity in plants preventing metabolism
- IR corn unaffected b/c enzyme changed in process and cross resistantance to SUs - IT corn was affected b/c 1 resistant gene isn't enough |
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What is the soil behavior of when Imis are applied?
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- weakly bound at pH's above 6.5
- at low pH's, herbicides will be bound - persistant in soil - react with Al and Fe |
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Is there more activity with the Imis with fast growth or slow growth of the weeds?
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fast growth
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What herbicides inhibit the enzyme ALS?
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Imidazolinones
Sulfonylureas Sulfonylanilides or Sulfonamides Pyrithiobac Bispyribac-Na |
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What Glufosinate PRE, PPI or POST and is it selective or non-selective?
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POST, non-selective
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How can you tell if your corn is Bt corn?
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Bt corn is glufosinate-resistant so if you spray it with glufosinate and it doesn't die then it is Bt corn
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What is the mechanism of glufosinate?
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inhibits the activity of glutamine synthetase in the plastid and cytosol - responsible for the conversion of ammonia into amino acids; causes a build up of toxic levels of ammonia, leading to cellular disruption and tissue death
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What is the tolerance of unaffected plants to glufosinate?
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enhanced metabolism by insertion of bar gene from Streptomyces hygroscopicus
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What is the mode/mechanism of action of glyphosate?
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- absorbed by leaf and green tissue (POST), undergoes extensive translocation in photosynthate stream to regions of action growth
- highly stable within plant - weak acid - inhibits amino acid and protein synthesis, specifically EPSP synthase - symptoms include lemon yellowing, wiliting and necrosis of young foliage |
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Why does glyphosate have no soil activity?
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because of phosphorus group
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What amino acids, etc does glyphosate block?
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- Tyr, Phe, Trp
- auxins - phytoalexins - pentose phosphate shunt |
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How are resistant or "Roundup Ready" crops tolerant to glyphosate?
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insertion of 'wild type' enzyme- CP4 gene
- this gene codes for the altered EPSP synthase (Gly -> Ala) and expressed at high levels to make multiple copies of less sensitive enzyme - when glyphosate is applied, the native enzyme is inhibited by the CP4 allows the production of the necessary amino acids |
