2/20/2017

Overview

• Phenoxy Class and MOA Effects of Phenoxy on • Fate of herbicides in soil • Landscape Trees & Shrubs How to read Herbicide Labels • Case study – real world examples By: Paul J. Pugliese, MPPPM • Who’s to blame? UGA Extension Coordinator • How to protect your business Bartow County • Integrated Weed Management

www.ugaextension.com/bartow

Phenoxy Chemical Class Familiar Brands  Mode of action:  Acts as a plant growth regulator (synthetic hormone) Uncontrolled cell division and growth  Selectively kills broadleaf weeds (trees & shrubs)  Used in lawns & pasture forage grasses (low toxicity)  Phenoxy Acids: 2,4‐D; 2,4‐DP; MCPA; MCPP Three‐Way and Triplet (2,4‐D  Benzoic Acids: + MCPP + dicamba) Escalade (2,4‐D + +  Carboxylic Acids (Pyridinoxy): , , dicamba) , , Fluroxypyr Spotlight  Often combined chemical formulations

Phenoxy Herbicide fate in soil fate

Break down in warm, moist soil from microbial • Many broadleaf herbicides contain action and photodegradation within 3‐6 months combinations of pheonxy chemicals in the During cool or dry conditions, can persist in soil amine salt form: for several months; high leachability • Makes them less volatile Surface applications usually do not penetrate • More soluble and more soil mobile more than 1 inch into clay soils • Label usually warns against: Irrigation can wash into mulched areas • spraying solution near desirable plants If applied to very dry soils, may be washed into • spraying the root zone of trees and shrubs soil cracks by rain or irrigation • exceeding the recommended rate within drip lines

1 2/20/2017

Herbicide Damage Symptoms

• 2,4‐D: • Twisting of the leaf petiole (epinasty), turning or curling the leaf upside down • Downward cupping of leaves • Narrow strap‐like leaves on youngest growth • May resemble injury from certain sap‐feeding insects, but petiole wouldn’t be twisted. • Certain virus diseases may also look similar

Phenoxy Herbicide Injury

Phenoxy Herbicide Injury ‐ Oak Herbicide Damage Symptoms

• Dicamba: • Leaf curling and twisting • Parallel leaf venation • Leaves tend to cup upward rather than downward • Proliferation of short shoots (witch’s broom) • Swelling of shoots • Abnormal elongation of leaf margins

Phenoxy Herbicide Injury

2 2/20/2017

Triclopyr Injury ‐ Poplar Herbicide Injury Diagnosis

 Soil Testing ‐ for phenoxy herbicide group ($100)  Plant tissue analysis ‐ for phenoxy herbicide group ($100)  Field Diagnostics:  Timing of injury within a few days or weeks of application(s): May see a delayed effect with newly planted trees/shrubs until roots reach treated areas.  Likely find adjacent plants with similar symptoms: Look for injury on two or more species Location of injured plants to areas treated

Areas of Concern  Dripline of a tree’s canopy is highest risk:  Older, established trees have a more extensive root zone as much as 2 to 3 times canopy width.  Research shows absorption roots may extend more than 2 times tree height  More than 50% of tree roots extend beyond the dripline  Grass clippings? Compost? Hay? Manure?  Sensitive tree species:  Boxelder, birch, catalpa, honeylocust, apple (crabapple), spruce, poplar, oaks, lilacs

Case Study: Typical Spray Schedule • Pictures taken in May 2011 for Commercial Lawn Care? • Development about 5 years old

40 oz. = 2.5 pints per acre 2.5 pints x 4 apps. = 10 pints in 7 months + spot treatment 10 pints = 1.25 gal. x 2.38 lbs. ae/gal. = 3 lbs. ae/acre

3 2/20/2017

4 2/20/2017

Lab Results of Phenoxyherbicide Plant Recovery from Phenoxy Damage Residue Foliage Sample • Depends on overall health and vigor of plants • Plants may recover from low doses with time • If lethal doses are absorbed, may persist in plants (and symptoms appear) for the next two or three seasons. • Exposure early in the growing season will be more severe (herbicide moves upward) than later in the  The lowest residue of 2,4‐D that will produce symptoms in year. susceptible tree species is 0.02ppm

Plant Recovery from Phenoxy Damage Who’s to blame?

• Irrigation can help leach herbicides and avoid Landscape designer? drought stress Herbicide manufacturer/EPA ‐ vague labels? • Don’t fertilize for one season after injury Local tree ordinances ‐ landscaping mandates? • Delay pruning for one year to fully assess injury Home Owner’s Association – expectations? • Activated charcoal only helps tie‐up residues, but must be applied before damage occurs. Turfgrass manager/herbicide applicator? • Remove trees that don’t improve within 1 year • Test soil for residual herbicides before replanting

5 2/20/2017

Tips for Avoiding Damage • Do not apply broadleaf herbicides during hot, windy conditions. • Avoid spraying near mulched trees and shrubs • Do not spray before heavy rainfall is expected • Don’t exceed labeled rate or application frequency • Rotate chemical classes (less dependent on phenoxy) • Carefully consider herbicides appropriate for site use • Avoid broadcast spraying during spring

Herbicide Modes of Action (Group 4 = Synthetic auxin) Broadleaf Weed Herbicides 1 ACCase inhibition 2 ALS or AHAS inhibition (Check labels for turf species) 3 Inhibit Microtubule Structure and Function 4 Synthetic auxin 5 Photosystem II inhibition (different binding site than Groups 6 and 7) Common Name Trade Name (Examples) 6 Photosystem II inhibition (different binding site than Groups 5 and 7) 7 Photosystem II inhibition (different binding site than Groups 5 and 6) 2,4-D (Various) 8 Fatty Acid and Lipid Biosynthesis Inhibitors 9 ESP synthase inhibition 10 Glutamine synthase inhibition bentazon Basagran® 11 Carotenoid Biosynthesis Inhibitors 12 Carotenoid Biosynthesis Inhibitors chlorsulfuron Corsair® 13 Carotenoid Biosynthesis Inhibitors 14 PPO inhibition 15 Inhibit Very Long Chain Fatty Acid (VLCFA) Synthesis clopyralid Lontrel® 16 Fatty Acid and Lipid Biosynthesis Inhibitors 17 Potential Nucleic Acid Inhibitors or Non‐Descript Mode of Action 18 Dihydropteroate Synthetase Inhibitors dicamba Vanquish® 19 Auxin transport inhibition 20 Cellulose Inhibitors fluroxypyr Spotlight® 21 Cellulose Inhibitors 22 Photosystem I Inhibitors 23 Inhibit Cell Division and Microtubule Organization and Polymerization MCPP ® 24 Oxidative Phosphorylation Uncouplers 25 Potential Nucleic Acid Inhibitors or Non‐Descript Mode of Action metsulfuron Blade®, Escort®, or Manor® 26 Potential Nucleic Acid Inhibitors or Non‐Descript Mode of Action 27 Carotenoid Biosynthesis Inhibitors 28 Cellulose Inhibitors or Potential Nucleic Acid Inhibitors or Non‐Descript Mode of Action Dismiss® Note: This table was originally prepared by Dr. Alan York, North Carolina State University and was updated by Drs. Eric Prostko, Stanley Culpepper, Tim Murphy, and Patrick McCullough, The University of Georgia, October 2011. triclopyr Turflon® trifloxysulfuron Monument®

Herbicide Combination Products www.georgiaturf.com Common Names Trade Name (Examples) 2,4-D + dicamba + MCPP Trimec Classic® 2,4-D + dicamba + MCPP + Trimec Plus® MSMA 2,4-D + triclopyr Chaser® Bookmark carfentrazone + 2,4-D + Speed Zone® Now! dicamba + MCPP carfentrazone + dicamba + Power Zone® MCPP + MCPA clopyralid + triclopyr Confront® clopyralid + 2,4-D + dicamba Millennium Ultra®

6 2/20/2017

Books for Weed ID Tips for Avoiding Damage  Integrated Weed Management: Rely more on timely pre‐emergent apps. Rotate to avoid resistant weeds Identify weeds and spray more selectively Keep turfgrass thick and healthy to avoid weeds Spot spray rather than broadcast spray Read and follow herbicide labels very closely! $14 Keep detailed records of herbicide applications Train your employees! Calibrate sprayers! Call UGA Office of Communications to order books at 706‐542‐2956 or online at http://t.uga.edu/22e

www.georgiaturf.com References

• http://www.extension.purdue.edu/extmedia/ID/ID_184_W.pdf • http://www.bartlett.com/resources/diagnosing-and-preventing- herbicide-injury-to-trees.pdf • http://njaes.rutgers.edu/pubs/publication.asp?pid=FS121 • http://www.extension.purdue.edu/extmedia/ws/ws-23-w.html Download • http://kentcoopextension.blogspot.com/2008/05/landscape- Apps Today! herbicide-damage-to-trees.html • http://turf.missouri.edu/stat/reports/report98/sense.htm

7