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Urea or Substituted Urea

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Urea or Substituted Urea

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    1. Urea or Substituted Urea Urea fertilizer is central component of structure PRE and POST “broadleaf” weed control Non-ionic, leaching correlated to solubility, but they are adsorbed by the soil (non-ionic bonding) 42 ppm to 2300 ppm Selective, non-selective (most by rate selection) and brush control Once upon a time there were more s-urea The term SU does not refer to this family MOA is inhibition of PSII, but at a different site than triazines – there is no “cross resistance” Not volatile and will not photodecompose.

    2. Urea

    3. Fluometuron – Cotoran, Cotton-Pro (Learn)

    4. Fluometuron – Cotoran, Cotton-Pro Used on only one crop – cotton, 5.3 M lbs in ’97 Water solubility = 110 ppm, half-life = 85 days Very good herbicide for broadleaf weed control in cotton; however, does cause injury to cotton on sandy soils. Use limited in OK because of this. Heavy usage in Delta states Better choice that prometryn for broadleaf weeds – cocklebur, morningglories, etc. Good “lay-by” herbicide, can be used “salvage” With a surfactant is good as PDS treatment

    5. Diuron – Karmex

    6. Diuron – Karmex, Direx A little over 4M lbs used on 21 U.S. crops Citrus* & cotton*, alfalfa, mint, walnuts, grapes Not include are soil sterilent uses Half-life about 90 days White crystalline solid, 42 ppm formulated as DF or as flowable Microbial breakdown Rates from around a pound or two to 60 lb/a

    7. Tebuthiuron - Spike

    8. Tebuthiuron - Spike Brush and woody plant control Sold as 20% pellet H2O = 2500 ppm, Half-life = 360 days Leaches down and taken up by tree roots Soil applied, may take 1-3 years to see full effect Industrial rate as high as 30 lb product/a – “silent spring” (see % above) Rates are as low as 3.75 lb product/a

    9. Linuron - Lorox

    10. Linuron – Lorox, Linex Crops limited mostly to small acreage or specialty crops. Still used on soybeans Use rates 0.5 to 1.5 lb a.i./a Formulated at DF or liquid flowable Mostly broadleaf weed control Water solubility is 75 ppm Half-life = 60 days

    11. Siduron - Tupersan

    12. Siduron – Tupersan “the odd ball” Does not inhibit PSII, it inhibits root growth Does not control broadleaf weeds, it kills grasses H2O solubility 18 ppm Can safely be used on bentgrasses for crabgrass control

    13. Bipyridylium The most toxic herbicide family LD50’s = 138 to 230 mg/kg, can blind you Emetic and bad odor added for safety Very strong cations, will not leach, no soil activity Contact herbicides, MOA = PSI, super oxides Very slow to degrade, but no activity, Half-life = 1000 days Ushered in the concept of No-till, reduced-till, etc. Most have very limited selectivity Postemergence and aquatic uses – DRIFT!!!

    14. Photosynthesis

    15. Paraquat Adsortion to Soil

    16. Paraquat – Gramoxone Max (learn)

    17. Paraquat – Gramoxone Max Maybe 5 M lbs used on 62 crops Does not include industrial and harvest aid uses Lower use rates than other 3 families H2O solubility = 620,000 ppm – NO LEACHING Super oxides, limited translocation in dark Must have a surfactant Rainfast in 30 minutes Said to be non-selective, but some are, peanuts Don’t use pond water!

    18. Diquat - Diquat

    19. Diquat - Diquat Harvest aids and aquatic weed control At approved rates will not harm fish H2O solubility = 718,000 ppm Safer than Paraquat, but still very toxic

    20. Difenzoquat - Avenge

    21. Difenzoquat - Avenge Technically, not in this family, but it fits here better than anywhere else H2O solubility = 817,000 ppm Controls wild oats in spring wheat, might in winter wheat, but grazing restriction

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