lecture 12

lecture 12 - 3/16/11 Herbicide Classifica.ons A....

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Unformatted text preview: 3/16/11 Herbicide Classifica.ons A. Herbicides – by ac.on Selec.ve Non ­selec.ve Contact Translocated Foliar applied (Postemergence) B. Herbicides – by placement (within .me and space) Soil applied (Preemergence) Early preplant Burndown Preplant Early post Preplant incorporated Post Preemergence Directed post C. Herbicides – by ac.vity (ac.ve life) Non ­residual  ­ beIer used as a post applica.on Residual – ac.ve for one season or less Short ­residual – ac.ve from a few days to a few weeks, use in most crops Long ­residual – ac.ve from a few weeks to several months or more Persistent – ac.ve from one to two seasons Highly Persistent*  ­ ac.ve for two or more seasons *long ­residual (highly persistent) herbicides that remain ac.ve longer than two growing seasons, should be used in permanent crops, non ­crop areas, or as an industrial herbicide Environmental concerns and possibly crop injury concerns increase as the residual ac.vity of the herbicide increases. Herbicide Classifica.ons 4. Herbicides – by modes of ac.on (families) 1. Growth Regulators 2. Amino Acid Synthesis Inhibitors 3. Lipid Synthesis Inhibitors 4. Pigment Inhibitors 5. Photosynthesis Inhibitors 6. Cell Membrane Disruptors 7. Cell Growth Inhibitors Mode of Ac.on(MOA) means the mechanism by which the herbicide kills the plant For example, the imidazolinones and sulfonylureas inhibit the synthesis of certain essen.al amino acids. Herbicide Groups According to Where or How They Injure Plants A. Herbicides that injure new growth and have the poten7al to move from leaves to roots B. Herbicides that injure old growth first and have the poten7al to move only upward C. Herbicides causing immediate localized injury with [email protected] or no movement D. Herbicides applied to the soil and have the poten7al to injure emerging seedlings 1 3/16/11 Classifica.on of Herbicides MOA 7 Classes Translocated Growth Regulators Amino Acid Inhibitors Lipid Synthesis Inhibitors Pigment Inhibitors Non ­Translocated Photosynthe.c Inhibitors Cell Membrane Disruptors Cell Growth Inhibitors Primary Sites of Ac.on of Some Common Herbicides A. Herbicides that injure new growth and have the poten7al to move from leaves to roots 1. Growth Regulators 2. Amino Acid Inhibitors 3. Lipid Synthesis Inhibitors (Grass Growing ­Point Disintegrators) 4. Pigment Inhibitors B. Herbicides that injure old growth first and have the poten7al to move only upward 5. Photosynthe.c Inhibitors C. Herbicides causing immediate localized injury with [email protected] or no movement 6. Cell Membrane Disruptors (Contact Herbicides) D. Herbicides applied to the soil and have the poten7al to injure emerging seedlings 7. Cell ­Growth Inhibitors 2 3/16/11 3 3/16/11 4 3/16/11 5 3/16/11 Most postemergence herbicides can also be divided into two basic groups: 1.  Contact herbicides  ­  usually cause rapid death of the plant  ­  do not translocate throughout the plant system  ­  need completely cover the weed to obtain adequate control  ­  Best results obtained when complete coverage is made to annual weeds 2 to 3 inches or less 2. Translocated herbicides  ­ move throughout the plant system before causing death to the plant  ­ kill plants slower than contact herbicides  ­ excessive rates may cause contact destruc.on of plant .ssue causing decrease weed control  ­ do not need completely cover the weed to obtain adequate control  ­ annual weeds can be larger than 2 to 3 inches Herbicide Classifica.on Example Herbicide Herbicide Formula.on Product Rate Range Flexstar 1.88L 1  ­ 1.6 pints/A • Flexstar (fomesafen) is a contact herbicide that controls annual broadleaf weeds in soybeans, including ragweeds, cocklebur, pigweeds, waterhemp, annual morningglories, velvetleaf, Pennsylvania smartweed, and black nightshade. Flexstar will suppress Canada thistle, bindweeds, and climbing milkweed, but does not control lambsquarters. • Mode of ac.on: cell membrane disruptor • Maximum rates of Flexstar: north of I ­70  ­ 1.3 pints; south of I ­70  ­ 1.6 pints. • Apply in a spray volume of 15 to 20 gpa (use 20 gpa in dense foliage) with a spray pressure of 30 to 60 psi. • Apply with COC or MSO (0.5 to 1% v/v) or NIS (0.25 to 0.5%), plus liquid nitrogen fer.lizer (minimum of 1% v/ v) or AMS (minimum of 4 lbs/100 gallons) MSO is the preferred adjuvant. • Flexstar may reduce the ac.vity of postemergence grass herbicides, especially under drought ­stress condi.ons. To avoid a reduc.on in grass control, apply Flexstar 2 to 3 days aeer the postemergence grass herbicide is applied, or wait about 7 days aeer Flexstar is applied before applying the grass herbicide. See label for more informa.on. • Flexstar oeen causes temporary soybean leaf burn. • Do not apply Flexstar more than once every two years to prevent carryover problems to rota.onal crops. 6 3/16/11 Herbicide Classifica.ons A. Herbicides – by ac.on Selec.ve Non ­selec.ve Contact Translocated Foliar applied (Postemergence) Burndown Early post Post Directed post B. Herbicides – by placement (within .me and space) Soil applied (Preemergence) Early preplant Preplant Preplant incorporated Preemergence C. Herbicides – by ac.vity (ac.ve life) Non ­residual  ­ beIer used as a post applica.on Residual – ac.ve for one season or less Short ­residual – ac.ve from a few days to a few weeks, use in most crops Long ­residual – ac.ve from a few weeks to several months or more Persistent – ac.ve from one to two seasons Highly Persistent*  ­ ac.ve for two or more seasons *long ­residual (highly persistent) herbicides that remain ac.ve longer than two growing seasons, should be used in permanent crops, non ­crop areas, or as an industrial herbicide Environmental concerns and possibly crop injury concerns increase as the residual ac.vity of the herbicide increases. Herbicide Classifica.ons 4. Herbicides – by modes of ac.on (families) 1. Growth Regulators 2. Amino Acid Synthesis Inhibitors 3. Lipid Synthesis Inhibitors 4. Pigment Inhibitors 5. Photosynthesis Inhibitors 6. Cell Membrane Disruptors 7. Cell Growth Inhibitors 7 3/16/11 Application Equipment 8 3/16/11 Effect of Spray Droplet Diameter on Target Coverage Droplet diam. (Microns) Type of Droplet Droplets/in sq (10GPA ) ___________________________________________________________ 20 wet fog 1,440,000 50 92,200 150 3,420 200 light rain 1,440 400 180 9 ...
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This note was uploaded on 04/03/2011 for the course BTNY 304 taught by Professor Staff during the Spring '08 term at Purdue.

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