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Using Herbicides Safely Around Woody Plants

Using Herbicides Safely Around Woody Plants. Off-site Movement of Herbicides 2013 Washington State Weed Conference. By: Paula Dinius, Urban Horticulturist WSU Chelan County Extension. Fate of Herbicides after Application. Image source: http://pubs.usgs.gov/fs/2006/3028/pdf/fs2006-3028.pdf.

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Using Herbicides Safely Around Woody Plants

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  1. Using Herbicides Safely Around Woody Plants Off-site Movement of Herbicides 2013 Washington State Weed Conference By: Paula Dinius, Urban Horticulturist WSU Chelan County Extension

  2. Fate of Herbicides after Application Image source: http://pubs.usgs.gov/fs/2006/3028/pdf/fs2006-3028.pdf

  3. Mechanisms of Off-site Herbicide Movement • Symptoms of Herbicide Injury • Case Studies Using Herbicides Around Trees & Shrubs

  4. Plant injury is usually caused by not following label directions. • Using around sensitive plants • Improper rate or method of application • Spraying during adverse weather conditions • Over/under irrigation Using Herbicides Around Trees & Shrubs

  5. Off-site movement is when any herbicide misses or moves from the intended treatment area. Using Herbicides Around Trees &Shrubs

  6. Mechanisms of Off-Site Movement Movement via air Volatilization - vapor Drift – droplet and granule dust Movement via soil water Leaching Run-off

  7. Off-site Movement ~ Volatilization High temperatures + low humidity = gas (vapor) Fumes travel for long distances Herbicide can volatilize right off plant or soil Dependent on molecular weight of herbicide

  8. Droplet drift is affected by • Weather conditions • Wind speed and direction • Temperature and humidity • Droplet size • Nozzle type, size & height • Spray pressure • Carrier • Type and volume Off-Site Movement Drift ~ Droplet http://www.ent.iastate.edu/images/misc/spraynozzles.jpg

  9. Influence of Droplet Size on Potential Distance of Drift Source - University of North Dakota

  10. Dust and Granular Formulations • Dust can drift farther and for longer duration than liquid. • Granular have less drift potential due to pellet size/weight. Off-site Movement Drift ~ Dust/Granular Image source: http://www.abc.net.au/news/image/997708-3x2-940x627.jpg

  11. Wind Speed Indicators Drift Potential Source: Herbicide Application Handbook. 2003. Monsanto

  12. Chronic Exposure to Phenoxy Herbicide Drift (Dicamba, 2,4-D, MCPP, etc.) Buffer Strip

  13. Leaching • Vertical • Run-off • Horizontal Off-Site Movement ~ Soil Water

  14. Rainfall or irrigation water can move herbicides down through or off the soil. • Potential depends on: • Solubility of herbicide • Adsorption to soil particles • Persistence of herbicide • Soil texture and structure • Amount and frequency of rainfall/irrigation Off-site Movement ~ Leaching & Run-off

  15. Herbicide Movement in Soil Herbicide Characteristics Solubility: Highly soluble herbicides are more likely to run-off or leach Image source: http://www.elmhurst.edu/~chm/vchembook/171solublesalts.html

  16. Herbicide Water Solubility No endorsement of products intended, used for example purpose only. Source: OSU Extension Pesticide Properties Database

  17. Herbicide Movement in Soil Herbicide Characteristics Absorbency – vegetation uptake Adsorbency – binding of a chemical to soil particles

  18. Herbicide Movement in Soil Herbicide Characteristics Persistence = resistance to breakdown in soil. (Half-life of herbicide in the soil) Degradation occurs mainly in O & A Horizon Factors influencing degradation: Microbes Soil chemical reactions Sunlight/temperature Image source: http://jupiter.plymouth.edu/~sci_ed/Turski/Courses/Earth_Science/soil_profile_diag.jpg

  19. Persistence in Soil No endorsement of products intended, used for example purpose only. Source: http://npic.orst.edu/ingred/ppdmove.htm

  20. Herbicide Movement in Soil Herbicide Characteristics Soil Profile • (Ad)Sorption Coefficient:

  21. Image source: http://turfgrass.cas.psu.edu/education/turgeon/Modules/11_WeedManagement/Herbicide_Fate/Content/HF16.html

  22. Herbicide Movement in Soil Soil Characteristics Soil texture: Sandy soils much more prone to leaching. Compacted clay soils are prone to runoff. Well aggregated loamy soils reduce herbicide movement. Image source: www.nj.nrcs.usda.gov/

  23. Herbicide Movement in Soil Soil Characteristics Organic matter: Soils high in OM have: Increased microbial activity Greater water holding capacity Greater adsorption capacity Image source: http://echezabalperiod2.wikispaces.com/file/view/Euplotespha-Ciliate_Protozoa-by_Ralf_Schmode.jpg; & http://www.teachengineering.org/view_activity.php?url=collection/nyu_/activities/nyu_permeability/nyu_permeability_activity1.xml

  24. Site Characteristics Slope: Greater the slope, greater potential of herbicide movement Herbicide Movement in Soil

  25. Awareness of Root Systems

  26. National Pesticide Information Center • OSU Extension Pesticide Properties Database • Based on Solubility, Koc, and Half-life • Pesticide Movement Rating • Very high – Very low http://npic.orst.edu/ingred/ppdmove.htm Herbicide Movement in Soil

  27. Herbicide Movement in Soil • National Pesticide Information Center • Pesticide Movement Rating • Pendimethalin (Prowl) = Very low • Dichlobenil (Casoron) = Moderate • Oryzalin (Surflan) = Low • 2,4 –D amine (Weedar 64) = Moderate • Isoxaben (Gallery) = Low • Dicamba (Banvel) = Very high • Picloram (Tordon) = Very high • Glyphosate (Roundup) = Extremely low • Benefin (Balan) = Extremely low Source http://npic.orst.edu/ingred/ppdmove.htm

  28. Herbicide Injury Symptoms

  29. Seedling Growth Inhibitor Herbicides Root & Shoot ~ Stunting & Distortion • Newly planted woody plants • Root tips enlarge into rounded structures and shoots can swell and be stunted. • Established woody plants • Stems enlarge and become brittle http://extension.agron.iastate.edu/soybean/documents/herbicideinjury_05.pdf

  30. Root & Shoot Inhibitors • Benefin – Balan • Pendimethalin – Pendulum, Prowl • Trifluralin – Treflan • Oryzalin – Surflan • Isoxaben – Gallery • Prodiamine – Barricade Seedling Growth Inhibitor Herbicides Trifluralin damage to spruce

  31. Systemic herbicides • Symptoms usually on new growth • Leaf cupping, twisting or strapping of leaves, splitting or cracking of bark • Prone to drift and can move with leading edge of soil water. Growth Regulator HerbicidesMalformed or Distorted ~ Leaves or Shoots Dicamba damage on Linden

  32. 2,4-D, MCPP, MCPA • Dicamba • Triclopyr, picloram, clopyralid Growth Regulator Herbicides Dicamba/2,4-D Damage on Pin Oak

  33. Phenoxy Damage on Conifers 2,4-D damage to pine & fir Invasive.org, Minnesota Department of Natural Resources Archive,

  34. Phenoxy Growth Regulator Herbicide Irregular contours herbicide damage on honey locust trunk (2,4-D, Dicamba, MCPP, etc.)

  35. Inhibition of photosynthesis causes various patterns of chlorosis. • Pre-emergence systemic herbicides absorbed by roots translocated to leaves. • Post emergent systemic • Symptoms more severe on side of herbicide placement. Herbicide Injury SymptomsLeaf Chlorosis or Necrosis Glyphosate damage

  36. At high rates, necrosis can occur without chlorosis. • Symptoms may persist for more than a year. • Symptoms may be confused with salt burn, drought, or freeze damage. Leaf Chlorosis or Necrosis Herbicide Picloram damage to maple

  37. Diuron = Karmex • Diruon + bromacil = Krovar • Imazapyr = Arsenal • Diquat and paraquat = Ortho Diquat, Reward • Oxyfluorfen = Goal Paraquat Damage on Pecan; Krovar damage on Zelkova Leaf Chlorosis or Necrosis Herbicides http://www.caes.uga.edu/commodities/fruits/pecan/media/images/paraquatdamage2.JPG

  38. Glyphosate damage (sublethal dose) • Chlorosis to necrosis • Shortened internodes • Stunted growth • Witches broom effect • Loss of apical dominance • Branch dieback Glyphosate Damage on Rose Distorted Growth and Chlorosis

  39. Case Studies Dichlobenil Picloram Trifluralin

  40. Dichlobenil (Casoron) and the Flowering Cherry Trees

  41. Flowering Cherry Tree Casoron Damage

  42. Picloram andthe Curb Cleaner

  43. Trifluralin and the Conifer Conundrum

  44. SummaryAlways Thoroughly Read & Follow All Pesticide Label Directions Study present & future weather conditions Temperature Wind speed & direction Humidity Rainfall Study plants found in surrounding area Identify species Tree and shrub root zone area Slope Choose herbicide to fit site conditions with considerations of potential movement

  45. Sources Washington State University. 2002. Turf & Ornamental WeedManagement Principles. MISC0170 Washington & Oregon State University & University of Idaho. 2005. Pacific Northwest Weed Management Handbook. Starbuck, Chris. 1998. Turfgrass Research & Information Report. University of Missouri-Columbia Turfgrass Research. http://agebb.missouri.edu/pdc/turf/report98/sesen.htm Cornell University. 1983. Dicamba (Banvel) Herbicide Profile 10/83. http://pmep.cce.cornell.edu/profiles/herb-growthreg/ Dexter A.G. 1993. Herbicide Spray Drift A-657 (Revised). North Dakota State University & University of Minnesota http://www.ext.nodak.edu/extpubs/plantsci/weeds/a657w.htm Ohio State University. Newsletter. Do “Drift Retardant” Chemicals Really Work? C.O.R.N. 2000 – 14. http://netc2000.tamu.edu/abstracts/tx009/paper/~corn/archive/2000/may00/00-15.html#linkg Costello, Perry, Matheny, Henry, & Geisel. 2003. University of California. Abiotic Disorders of Landscape Plants A diagnostic Guide. Publ. 3420. Sinclair, Lyon. & Johnson.1987. Cornell University. Diseases of Trees and Shrubs Voge, Derle, and Jenkins. 1994. Oregon State University Extension. OSU Extension Pesticide properties Database. National Pesticide Information Center. http://npic.orst.edu/ingred/ppdmove.htm

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