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Imprelis® Damage to Trees Primer

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What is Imprelis®?

A Broadleaf Herbicide for Turf and Right-of-way Use

Introduced by DuPont in Spring, 2011

Active Ingredient: aminocyclopyrachlor

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“Control Weeds Even on Rainy Days

DuPont Imprelis herbicide...control dandelion, clover and plantains, as well as tough broadleaf weeds...even during reseeding or rainy days...a low application rate... and is the first compound in an advanced generation of herbicides.”

Why Imprelis®

Turf Magazine - November, 2010TURF SCIENCENew Products

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“Imprelis® is readily absorbed by plant leaves and roots, stopping the growth of target weeds by interfering with the hormonal balance necessary for normal shoot and root development.”

How does Imprelis® Work?

Turf Magazine - November, 2010TURF SCIENCENew Products

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Clopyralid introduced. . . as a broadleaf herbicide.

Clopyralid found in organics waste stream.

Decomposition processes in compost...did not degrade the molecule.

Compost was herbicidal.

Imprelis® related to Clopyralid

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Imprelis®

Long residual -- not biodegradable

High concentrations remain in plants

Herbicidal at very low concentrations

Recycled in grass clippings and tree leaves

Chemical moves with water

Evergreen & deciduous plants affected

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• Higher water solubility: > 30 ppm (solubility of an herbicide in room temperature water)

• Longer soil half life: > 21 days time (time required for herbicide to degrade to ½ of its previous concentration in soil)

• Lower soil adsorption: Koc < 300 – 500

Adapted from: Becker, R.L., D. Herzfeld, K.R. Ostlie, and E.J. Stamm-Katovich. 1989.Pesticides: Surface Runoff, Leaching, and Exposure Concerns. MinnesotaExtension Service Clean Water Publication AG-BU-3911.

Red flags for increased leaching potential

(Koc = Organic carbon partitioning coefficient)

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Tree Roots

How wide are tree root systems? Historically root systems were thought to be under the dripline of treesBut now we know root systems can grow to cover an area 2-3 times the width of the dripline.

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Shared root zones

When turf grasses, weeds, herbaceous plants, shrubs, and especially trees share space above ground in a landscape, they also share:• root space below ground.

• common points of entry for herbicides

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How many potential herbicide points of entry can you find in these pictures?

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What Did DuPont Do?

Introduced by DuPont in Spring, 2011

By June, 2011, damage to trees and shrubs was reported...

By end of summer 2011, Imprelis® was pulled from use

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What plants are affected?

All woody trees, shrubs, vines

Damages new growth

Spruce, honey locust, cottonwood are especially sensitive

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Symptoms of Imprelis® Damage

Dead buds, shoots, pine candles

Twisted, fused needles

Contorted, chlorotic leaves

Tumorous growths on twigs, stems

Twisted, “stretched” twig growth

Death

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Symptoms of Imprelis® Damage

Colorado Sprucedieback, galls, stem swelling

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Symptoms of Imprelis® Damage

Colorado Sprucefused needles

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Symptoms of Imprelis® Damage

Black Hills Spruce

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Symptoms of Imprelis® Damage

Norway Spruce - death

Twisted growth

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Symptoms of Imprelis® Damage

White Pine: 2011 on the left, 2012 on the right

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Symptoms of Imprelis® Damage

White Pine

Needle death, swollen twigs, galls, distorted needles

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Symptoms of Imprelis® Damage

Northern White Cedarneedle & twig deathstunted growth, galls

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Symptoms of Imprelis® Damage

Honeylocust

Leaf distortion, dieback, similar to plant bug infestation

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Symptoms of Imprelis® Damage

HoneylocustGalls on twigs,

branches and stems

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Symptoms of Imprelis® Damage

Ginkgo

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Symptoms of Imprelis® Damage

Freeman MapleDistorted terminal growth

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Symptoms of Imprelis® Damage

CottonwoodLeaf distortionTip diebackDeath of big toothed aspen

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Mitigation Measures

Prune & remove damaged growth Remove all contaminated materials

Including grass clippings, leaves, wood & other plant debris until at least 2014

Burn or landfill affected yard waste

For replacement plantings Avoid planting new trees down slope Remove & replace contaminated soil Amend edges of excavation w/ activated carbon

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Compensation for Tree Loss?

Carefully document all damage: Maintenance records Dates Photos Symtomology

DuPont claim site: www.imprelis-facts.com Only through 2013

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For More Information

Imprelis® Update: 2012 Field Notes on Injury and Recovery. www.ppdl.purdue.edu.

A Turf Professional’s Guide to Suspected Imprelis® Herbicide Injury in the Landscape. www.ppdl.purdue.edu/PPDL/pubs/briefs/ImprelisLCO.pdf

MDA: raymond.pigati@state.mn.us

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Questions

All Imprelis® symptoms images were generously shared by

Manuel Jordan: Heritage Shade Tree Consultants and

John Lloyd: Plant Health Doctors.com