WHAT YOU SHOULD KNOW ABOUT TORDON HERBICIDESVegetation managers and foresters use

Tordon* herbicides to control unwanted weeds,brush and trees beneath electrical powerlines,along railroad beds, roadsides, pipelines, incommercial forestry, and wildlife openingsincluding grazed areas on these sites. Tordon isa trademark of Dow AgroSciences for herbi-cides containing picloram as the active ingredi-ent.

The following information providesspecifics on Tordon, and explores questionscommonly asked by people concerning its use.

Why do you need to control vegetation in theseareas?

For most rights-of-way uses, safety re-mains a major reason for managing vegetation.Trees, brush and weeds along these rights-of-way can create hazards.

For driver and passenger safety, vegeta-tion must not be allowed to block traffic signs orroadside markers. It must also not concealguardrails or overtake road shoulders. Vegeta-tion must not obstruct driver vision at intersec-tions or block the line of sight around curves.Excessive vegetation also prevents properdrainage, which can damage roadbeds by cre-ating potholes and other hazards.

Trees growing into powerlines can causeelectrical power outages and make mainte-nance difficult and dangerous. In addition,areas around utility substations and landbeneath transmission towers require a vegeta-tion-free zone to prevent fire hazards andensure the transfer of electricity.

Railroad companies need to controlweeds along their rights-of-way to maintainroadbeds. Weeds hold water around railroadties. This causes them to rot, increasingchances for derailment accidents. Sparks fromthe rails can also ignite weeds and brush grow-ing too close to the roadbed, which can create afire hazard for neighboring residents. Brush thatobstructs motorists’ views at railroad crossingsis especially dangerous. Controlling it can helpavert car/train accidents.

Foresters control vegetation to maximizethe amount of timber they can harvest resultingin more timber harvested on less land. Control-ling brush also decreases the potential for forestfires, and allows young stands to get started.

Invasive plants, that affect all of the areaswe have talked about, threaten to create amonoculture where one plant type dominates anarea. Invasive plants choke out native plantspecies and wildlife habitats. Soon nativegrasses, flowers and other plant species, alongwith native animals and birds, are driven out ofthe area.

Selective herbicides control these invasiveplant species which promotes native plants thatin turn attract a wide range of wildlife. Nearly 50years of research by Dr. William Bramble, a for-est ecologist, and Dr. William Brynes, an ecolo-gist specializing in forest soils, support the useof selective herbicides to increase biodiversity.(The Bramble and Brynes study was done inconjunction with Penn State University, PurdueUniversity and the Pennsylvania GameCommission.)

Why do you need to use Tordon? — Can’t youjust cut the vegetation?

Mowing and trimming remain importantparts of any vegetation maintenance program.But mechanical means alone cannot protectthese areas adequately. Besides being verylabor intensive, mechanical methods cause soilcompaction that can lead to soil erosion. Andflailing blades and moving parts pose a dangerto employees, livestock and wildlife. Flyingdebris from mowers can potentially damageyour property.

Mowing creates multiple resprouts — theplant’s natural defense to the cutting. This onlyworsens the vegetation problem.

In some cases, mechanical methods quitesimply cannot be used. Steep terrain may limitaccess by mowers, and in the case of railroadsand substations, their crushed-stone construc-tion makes mechanical weed control impossible.

Tordon controls unwanted brush and elim-inates resprouting. Because of this improvedcontrol, crews and heavy machinery visit thearea less frequently, meaning less impact onproperty near yours.

Who will be applying Tordon?A vegetation manager plans Tordon

herbicide treatments and oversees crew activities. Trained, professional applicatorsapply Tordon in designated areas usingapproved application techniques. Organizationsmay use on-staff crews or hire custom applica-tors. In either case, these applicators followdirections on the product label, which isreviewed by the Environmental ProtectionAgency.

Aerial applicators are highly trained anduse specialized equipment to make applications

How do I know these applicators are trainedproperly?

It’s in the best interest of any organizationto hire qualified people to handle applications— for the good of the organization itself and itsstanding in the community.

Only state-certified applicators or thoseunder their direct supervision may apply Tordon.Tordon herbicides are classified as restricted-use pesticides because of their ability to injuresusceptible plants at extremely low rates. Therigorous training required for state certificationhelps ensure that applicators apply Tordonproperly, limiting the potential for damage tonontarget vegetation.

In addition, an experienced crew foremanoversees the application process toensure all workers follow the specified vegeta-tion-control plan outlined by the vegetation man-ager.

How will they apply Tordon?Crews apply Tordon to unwanted vegeta-

tion through a variety of application techniques.Foliar applications spray solution on the plant’sleaves, while cut-stubble applications are usedto keep mowed brush from resprouting.

The vegetation manager assesses plantvariety and size, and environmental conditionsat each site before determining the correct

application rate and technique for that location.The manager considers many factors, such asseason, temperature, weather and terrain.

How do these applicators know they are applying the correct amount of Tordon?

The label indicates the rates to be used.Before an application begins, crews test theapplication equipment and calibrate all spraynozzles to ensure they meet these label direc-tions.

Will Tordon harm my ornamentals or garden?Tordon has the potential to harm any

woody or broadleaf plant that comes in directcontact with the spray solution. Therefore, appli-cators take care to apply Tordon only on tar-geted vegetation specified by the vegetationmanager.

Crews use extra caution to protect yourornamentals or garden, leaving untreated“buffer” zones that add an extra measure of pro-tection. When making foliar applications, crewscarefully monitor wind speed and direction toassure accuracy. Drift-control agents can alsobe mixed with the spray solution to producelarger, heavier droplets that aid applicationaccuracy and reduce chances for off-target drift.

Is Tordon considered toxic?Picloram, the active ingredient in Tordon,

has been classified as Category E – “evidenceof non-carcinogenicity to humans” by the EPA(the most favorable classification possible), andhas been found to be “practically nontoxic” tomammals, birds, and honeybees. Toxicologicalstudies show no evidence that the active ingre-dient in Tordon causes cancer, birth defects,genetic damage, genetic mutations, adverseeffects on the immune system or nervous sys-tem in humans.

All pesticides sold in the U.S. must beregistered by the EPA based on scientific stud-ies showing that the pesticide will perform itsintended function without unreasonable adverseeffects on the environment. The EPA definesunreasonable adverse effects as any unreason-able risk to man or the environment, taking intoaccount the economic, social and environmen-tal costs and benefits of the use of the pesticide.

How do you know the amount of Tordonapplied won’t hurt animals?

Tordon affects plants only. The herbicide’sactive ingredient disrupts the growth processwithin the plant by affecting enzymes unique toplants. Tordon does not have a similar effect onanimals or insects.

To ensure there are no unintended effectsto pets, livestock or wildlife, the EPA requiresextensive animal testing. Researchers deter-mine the highest concentration of a product thatstill shows no negative effect on animals, andcall this the No-Observable-Adverse-EffectLevel (NOAEL).

Scientists also determine a maximumexposure level — exposure to the highest esti-mated concentration level that could beexpected with normal use. Using these twomeasurements, they calculate a “safety factor”for effects on animals. This factor shows a multi-ple of the highest label application rate that ananimal would have to be exposed to in order toreach the NOAEL.

For instance, a safety factor of 10X meansthat an animal would have to be exposed to tentimes the maximum labeled application rate ofTordon to reach the NOAEL.

As you can see in the Safety Assessmentchart, a large margin of safety exists. Safety fac-tors for wildlife range from 24X to 715X.

In addition to the safety factor, you’ll alsofind a relative toxicity designation. Scientistsgroup substances together according to theirtoxicity level, as you see on the scale below.

How does this relate to my protection?To avoid exposure from the application,

stay away from the treated area until the vegeta-tion has dried. Since the product degrades in ashort time and is absorbed into the vegetation,you can control your exposure by using com-mon sense and avoiding the area until the vege-tation has dried. If you were to becomeexposed, it would happen through either acci-dental ingestion, like eating treated berries, orskin absorption from touching treated vegetationbefore it dries completely. The next two sectionswill address these two situations.

What if I have eaten some treated berries?You should not consume berries that have

been treated with Tordon. However, scientistshave studied accidental ingestion. These stud-ies, like the animal studies mentioned above,use the No-Observable-Adverse-Effect Level(NOAEL) as a benchmark. Based on thesestudies and residue levels likely to be found atthe highest labeled use rate, scientists havedetermined that an average person (150pounds) could accidentally consume 30 quartsof treated berries each day for the rest of his orher life without experiencing any adverseeffects.

What if I walk across a treated area?Exposure may occur from walking across

an area still damp from a foliar treatment.However, the dose you’d receive from this typeof activity is not likely to cause any harm. UsingNOAEL figures and the maximum expectedexposure, scientists have determined that anaverage person (150 pounds) has a safety fac-tor of 10,000† times over the exposure receivedwhen walking through an area that was sprayed

Practically Nontoxic

Slightly Toxic

Moderately Toxic

Highly Toxic

Very Highly Toxic

TOXICITY SCALE

LOW

HIGH

Safety ToxicityAnimal Type of Exposure Factor Category

Bobwhite Diet 715X PracticallyNontoxic

Mallard Diet 715X PracticallyNontoxic

Bluegill Freshwater 85X SlightlyToxic

Rainbow Trout Freshwater 43X SlightlyToxic

Daphinia magna Freshwater 67X SlightlyToxic

Eastern Oysters Saltwater 24X SlightlyToxic

Pink Shrimp Saltwater 148X PracticallyNontoxic

SAFETY ASSESSMENT FOR WILDLIFE

at the maximum labeled rate. Still, we do notrecommend walking through a treated area untilthe vegetation has dried completely.

Do I need to stay indoors during the application?

No. However, it’s a good idea to stay awayfrom the application site during treatment andshortly after.

After applicators apply the foliar treat-ment, avoid the area until the vegetation dries.

What happens to plants after they’ve beentreated?

The active ingredient, picloram, works likea growth regulator found only in plants. It enterstreated vegetation through the leaves andstems, and uses the plant’s own transportationsystem to move into the roots and leaves. Itinduces rapid growth, which disrupts food pro-duction and causes the plant to die from lack ofnutrients.

Will Tordon remain in the soil?Tordon is broken down by soil micro-

organisms (fungi and bacteria) and sunlight.Final breakdown products are carbon dioxide,water and other organic materials. The break-down rate depends on rainfall, soil temperatureand how these factors impact soil microorgan-ism activity — the main cause of breakdown.The time required to break down 50 percent ofthe active ingredient ranges from 1 week to 4months.

Is it likely that Tordon will seep into groundwater?

Although the potential for leaching exists,Dow AgroSciences strongly believes thechances are slight that Tordon will seep intogroundwater. Should any Tordon enter the soil,organic matter and clay particles in most soilswill limit its downward movement, and keep itfrom contaminating groundwater.

However, a limited number of applicationsites may lack adequate amounts of clay parti-cles or organic material to absorb Tordon orother herbicides. In groundwater monitoringwork compiled by US EPA, samples from nearly3000 wells were analyzed for residues of piclo-ram, with detection in only 2.5% of the wells.Much of this sampling was done in areas atpotentially high risk for groundwater contamina-tion. All detects were extremely low, (16 ppb orless); far below any of the human health guide-lines.

As a precaution, and to minimize thepotential for non-point source contamination, agroundwater advisory statement occurs on theproduct label. This statement does the following:

• directs users not to apply picloram on certain types of sites that are vulnerable to groundwater contamination.

• provides guidance on the identification of these sites.

When certified applicators avoid thesetwo site conditions, and proper applicationtechniques are followed, the potential forgroundwater contamination can be minimized.

Who may I contact for more information?Contact your Dow AgroSciences sales

specialist or visit our Web site at www.dow-agro.com/ivm. To receive printed materials,please fax your request to Dow AgroSciences at1-800-905-7326. If you have further questions orrequire technical assistance, please contact ourCustomer Information Center via e-mail atinfo@dowagro.com or call 1-800-263-1196.

V01-112-002 (01/02) DASEPI 109284

Printed on recycled paper

†Margin of safety values taken from Environmental Impact Statement - USDA Forest Service - January 1989.

*Trademark of Dow AgroSciences LLC