Telar

Talkin' About Telar

There's a proposal to use the herbicide Telar to try to control pepperweed in the Laguna.

To support that decision-making process, this webpage includes information about the herbicide Telar in two forms:

(1) A full-page article that summarizes the risks of harm.

* The text of this article is on this webpage; to see it, click here.

* To download a formatted version of this longer article, click here.

(2) A half-page article published in The Next STEP.

* The text of this article is on this webpage; to see it, click here.

This webpage also includes the footnote information for that article (which has not yet been uploaded to the City's webpage); to see it, click here.

* To download the full issue of The Next STEP, click here.

You can also see more about pepperweed at http://tncweeds.ucdavis.edu/esadocs/lepilati.html.

Talkin' About Telar
By Patricia Dines
(c) Patricia Dines, 2005. All rights reserved.

More detailed version.

Telar, with the active ingredient chlorsulfuron, is a broad-spectrum pre- and post-emergent herbicide used to control weeds on cereal grains, pasture and rangeland, industrial sites, and turf grass.1 A sulfonylurea herbicide, it works by inhibiting the synthesis of key amino acids in plants, thus stopping cell growth.2 It inhibits seed formation and the production of viable seeds.3

* KILLS NON-TARGET PLANTS: Unfortunately, because it's broad-spectrum, Telar doesn't just kill the intended plants. This can put at risk a variety of other plants &endash; including the rich variety of native plants that make up the Laguna ecosystem &endash; feeding wildlife and providing us all with natural beauty.

The EPA recently said that chlorsulfuron poses "risks of concern to non-target plants exposed through drift, runoff, or direct application." They're proposing increased limits on its use, but said that they expected that even these would not be sufficient. They requested public suggestions for other ways to reduce its risk of harm, especially to endangered plants.1 This action by the EPA indicates that use according to the current label is creating harm above the amount that they consider acceptable.

Ontario Food & Agriculture lists a variety of annual and perennial broad-leaf plants that chlorsulfuron can harm.4 Has anyone identified which local desirable plants (crops, natives, etc.) could also be harmed by Telar? Are we ready to harm these plants too?

It doesn't take much to hurt non-target plants; chlorsulfuron is potent in very small doses. According to Ontario Food & Ag, "extremely low residues can be highly toxic to some broadleaf weeds, such as wild carrot, for up to 2 years after application."4 Studies show that minute exposures of sulfonylureas reduce fruit and seed production, even at a level of one thousandth of typical agricultural application rates - and often without visible signs of injury to the vegetative parts of the plant. Studies showed similar results for cherries, garden peas, canola, soybeans, sunflower, and smartweed.2

Researchers in one study started their report saying that sulfonylurea herbicides could have a "devastating impact." They concluded that "drifting sulfonylureas may severely reduce both crop yields and fruit development on native plants, an important component of the habitat and foodweb for wildlife."2

This can be especially crucial for endangered plants, where only a few stands of the plant even exist. An early study of another sulfonylurea herbicide (sulfometuron methyl) showed that it easily killed endangered plants. The Fish and Wildlife Service recommended it be prohibited in counties where road use could eliminate the small remaining stands of endangered plants, but only very minor such limits were placed on its use.2

Telar's label includes this notice: "It is impossible to eliminate all risk associated with use of this product... These risks can include: ineffectiveness of the product; crop injury, or; injury to non-target crops or plants. DuPont does not agree to be an insurer of these risks. WHEN YOU BUY THIS PRODUCT, YOU AGREE TO ACCEPT THESE RISKS." (their caps)

* MOVES IN WATER: Telar's label states, "Do not apply directly to water, or to areas where surface water is present, or to intertidal areas below the mean high watermark.... Do not apply in irrigation ditches or canals including their outer banks."5 Label warnings have the force of law, the regulatory response to serious harmful effects. Telar has been found in streams and killed desirable vegetation and fish. The EPA says that sulfonylurea herbicides are "relatively mobile in soil," and have a "high intrinsic leaching potential."2 Given that Telar can remain toxic for two years, that gives two rainy seasons for this material to travel far beyond it's initial application site. California state lists chlorsulfuron as a Potential Groundwater Contaminant.6

* HARMS PEOPLE AND ANIMALS: Telar is listed as a Developmental Toxin and a Male and Female Reproductive Toxin under California's Proposition 657 and in the U.S. Toxic Release Inventory (TRI).8 Studies show that it can cause a variety of developmental effects on frogs, including malformed limbs and increased mortality. One study concludes that sulfonylurea herbicides cause developmental effects by disrupting thyroid function, which, they say, "is capable of producing a myriad of deleterious effects."2

Telar also has acute health risks to humans and animals. DuPont's own material indicates that it is an eye irritant and can cause discomfort, tearing, and blurring of vision, as well as "lung changes, weakness and other nonspecific effects." It warns "Harmful if swallowed or absorbed through the skin. Avoid contact with skin, eyes, or clothing...Avoid breathing vapors or mist ... Wash hands before eating, drinking, [etc.]... Runoff from fire control may be a pollution hazard....Burning chemicals may produce by-products more toxic than the original material."9

* HARMS SOIL BACTERIA: Working quietly behind the scenes, soil bacteria are a key basis for healthy plants and ecosystems. Sulfonylurea herbicides inhibit an enzyme that some soil microorganisms require. One study of another sulfonylurea herbicide found that it inhibited the growth of 5 soil bacteria species. The biologists concluded that the herbicide's application "would have significant effects on the microbial ecological balance of the soil."2

Another study compared this Telar-relative with sawdust mulch, and found that it reduced both the soil nitrogen content and the abundance of microorganisms, while the mulch increased both.

* CONCLUSION: Telar is potent in very small doses for up to two years, moves easily in water and soil, and can cause notable harm to crops, native plants, wildlife, humans, our water supply, and the functioning of ecosystems. Let's remember these risks in this decision-making process.

Thank you to NCAP (Northwest Coalition for Alternatives to Pesticides) for their assistance in gathering this information.

ENDNOTES

1 - "Chlorsulfuron Risk Assessments and Preliminary Risk Reduction Options (Phase 3 of 4-Phase Process); Notice of Availability," Environmental Protection Agency (EPA), Federal Register, Sept. 24, 2004. <www.epa.gov/fedrgstr/EPA-PEST/2004/September/Day-24/p21510.htm>

Note: This is a notice indicating that current regulations are not offering sufficient protection from chlorsulfuron from risks "to non-target plants exposed through drift, runoff, or direct application," especially endangered plants. This means that, even when used according to the label, more than what they consider an acceptable level of harm is happening.

2 - "Herbicide Fact Sheet: Sulfometuron Methyl," Caroline Cox, Journal of Pesticide Reform, Winter 2002, Vol. 22, No. 4; Northwest Coalition for Alternatives to Pesticides (NCAP). <ww.pesticide.org/sulfometuron.pdf>

Note: Both sulfometuron methyl and chlorsulfuron are sulfonylurea herbicides, and this fact sheet includes information on that herbicide family.

3 - "Noxious/Selective Weed Control: Escort® XP herbicide; Telar® DF herbicide," DuPont product literature. <www.dupont.com/ag/vm/literature/H-91350.pdf>

4 - Guide to Weed Control 2004-2005, Ontario Ministry of Food & Agriculture, Publication 75, Chapter 4. <www.gov.on.ca/OMAFRA/english/crops/facts/notes/chlorsulfuron.htm>

5 - "Telar® DF herbicide", DuPont Product Label. <www.cwc-chemical.com/Downloads/EIDuPontProducts/TelarLabel.pdf>

6 - Pesticide Action Network (PAN) Pesticides Database, Pesticide Registration Status: Chlorsulfuron. <www.pesticideinfo.org/Detail_ChemReg.jsp?Rec_Id=PC35428>

7- "Chemicals Known To The State To Cause Cancer Or Reproductive Toxicity," Proposition 65 list, California Office of Environmental Health Hazard Assessment, Feb.11, 2005. <www.oehha.org/prop65/prop65_list/Newlist.html>. The direct link is <www.oehha.org/prop65/prop65_list/files/P65single21105.pdf>

8 - Environmental Protection Agency (EPA). <www.epa.gov/tri/chemical/index.htm>

9 - DuPont Material Safety Data Sheet (MSDS) <www.dot.ca.gov/dist05/maint/ivm/msdsfiles/telar_msds.pdf>

===

ADDED ISSUE: PLANT RESISTANCE TO THE HERBICIDE

Information from the Canadian government states: "Do not apply Telar herbicide more often than once every 3 years. Do not make consecutive applications of Telar without alternating with a sequential partner herbicide. These precautions are necessary to prevent selection of weed biotypes resistant to Telar." <www1.agric.gov.ab.ca/general/pesticide.nsf/0/C152A0CA2B4C0AFC87256E62_>

Does the proposed plan for the the Laguna take resistance and this procedure into account? It sounds like they plan to spray Telar multiple years in a row.

Telar's own label says: "Biotypes of certain weeds listed on this label are resistant to Telar DF.. If weed control is unsatisfactory, it may be necessary to spray problem areas using a product with a different mode of action."5 Their product literature lists 19 weeds that are known to have resistent biotypes, and they say that the distribution of some of them is "widespread."

<www.dupont.com/ag/vm/literature/H-91350.pdf>

Resistance is one of the reasons that users get on a pesticide treadmill, needing more and stronger pesticides, causing increasing secondary damage &endash; while the underlying causes of the original problem go unaddressed, and can even get worse.

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Talkin' About Telar
By Patricia Dines
(c) Patricia Dines, 2005. All rights reserved.

Shorter version. Published in: The Next STEP, Volume V, Number 2, March/April 2005

Telar's active ingredient chlorsulfuron is a broad-spectrum herbicide for weeds in cereal grains, rangeland, and industrial sites.(1) A sulfonylurea herbicide, it inhibits plants' synthesis of key amino acids, stopping cell growth (2) and the production of viable seeds.(3)

* KILLS NON-TARGET PLANTS: Unfortunately, because it's broad-spectrum, Telar can also put at risk a variety of "non-target plants"&emdash; including the Laguna's rich variety of native plants that provide food and habitat for wildlife and provide us all with natural beauty. The EPA recently said that chlorsulfuron poses "risks of concern to non-target plants exposed through drift, runoff, or direct application" and requested public suggestions for reducing those risks, especially to endangered plants.(1)

Ontario Food & Agriculture lists a variety of annual and perennial broad-leaf plants that chlorsulfuron can harm, and says that "extremely low residues can be highly toxic to some broadleaf weeds, such as wild carrot, for up to 2 years after application."(4) Studies show that very minute exposures of sulfonylureas reduce fruit and seed production, and can severely reduce crop yields and fruit development on native plants that feed wildlife&emdash;even threatening the last stands of endangered species.(2)

* MOVES IN WATER: Telar's label states, "Do not apply directly to water, or to areas where surface water is present, or to intertidal areas below the mean high watermark.... Do not apply in irrigation ditches or canals including their outer banks."(5) Label warnings have the force of law, the regulatory response to serious harmful effects. And Telar has been found in streams and killed desirable vegetation and fish. The EPA says that sulfonylurea herbicides are "relatively mobile in soil," and have a "high intrinsic leaching potential."(2) California lists chlorsulfuron as a Potential Groundwater Contaminant.(6)

* HARMS PEOPLE AND ANIMALS: Telar is listed as a Developmental Toxin and a Reproductive Toxin under California's Proposition 65.(7) Studies show that it can cause developmental harm to frogs, including malformed limbs and increased mortality. One study concludes that sulfonylurea herbicides cause developmental effects by disrupting thyroid function, which, they say, "is capable of producing a myriad of deleterious effects."(2)

Thank you to Northwest Coalition for Alternatives to Pesticides (NCAP) for assisting with this article.

SOURCES: Environmental Protection Agency (EPA), DuPont (product manufacturer), Ontario Food & Agriculture's Guide to Weed Control, Northwest Coalition for Alternatives to Pesticides (NCAP), Pesticide Action Network,and California Office of Environmental Health Hazard Assessment.

Footnotes

Note: This is a notice indicating that current regulations are not offering sufficient protection from chlorsulfuron "to non-target plants exposed through drift, runoff, or direct application," especially endangered plants. This means that, even when used according to the label, more than what they consider an acceptable level of harm is happening.

Note: Both sulfometuron methyl and chlorsulfuron are sulfonylurea herbicides, and this fact sheet includes information on that herbicide family.

3 - "Noxious/Selective Weed Control: Escort® XP herbicide; Telar® DF herbicide," DuPont product literature. <www.dupont.com/ag/vm/literature/H-91350.pdf>

4 - Guide to Weed Control 2004-2005, Ontario Ministry of Food & Agriculture, Publication 75, Chapter 4. <www.gov.on.ca/OMAFRA/english/crops/facts/notes/chlorsulfuron.htm>

5 - "Telar® DF herbicide", DuPont Product Label. <www.cwc-chemical.com/Downloads/EIDuPontProducts/TelarLabel.pdf>

6 - Pesticide Action Network (PAN) Pesticides Database, Pesticide Registration Status: Chlorsulfuron. <www.pesticideinfo.org/Detail_ChemReg.jsp?Rec_Id=PC35428>

7 - "Chemicals Known To The State To Cause Cancer Or Reproductive Toxicity," Proposition 65 list, California Office of Environmental Health Hazard Assessment, Feb.11, 2005. <www.oehha.org/prop65/prop65_list/Newlist.html>. The direct link is <www.oehha.org/prop65/prop65_list/files/P65single21105.pdf>

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