Picloram

Extracted Attributes

• Primary Use

  Systemic herbicide for woody plant and broadleaf weed control

• Health Risks

  Genetic expression errors (epigenetics) correlated with young-onset colorectal cancer, liver and kidney effects

• Chemical Name

  4-amino-3,5,6-trichloropicolinic acid

• Chemical Class

  Pyridinecarboxylic acid

• Original Developer

  Dow Chemical Company

• EPA Carcinogen Classification

  Group E (evidence of non-carcinogenicity, though contains hexachlorobenzene contaminants)

Timeline

• Picloram is developed by the Dow Chemical Company. (Source: web_search_results)

  1963-01-01

• Picloram is combined with other herbicides to make Agent White for use as a jungle defoliant during the Vietnam War. (Source: Wikipedia)

  1965-01-01

• Over 413,000 pounds of picloram are used in the United States, primarily by government and industry. (Source: Wikipedia)

  1974-12-31

• The EPA reregisters picloram and its derivatives as Restricted Use Pesticides due to hazards to non-target plants. (Source: web_search_results)

  1995-08-01

• The EPA issues an update on the reregistration of picloram and its three main derivatives. (Source: web_search_results)

  2007-11-01

Picloram

Picloram is a systemic herbicide used for general woody plant control. It also controls a wide range of broad-leaved weeds, but most grasses are resistant. A chlorinated derivative of picolinic acid, picloram is in the pyridine family of herbicides. Picloram can be sprayed on foliage, injected into plants, applied to cut surfaces, or placed at the base of the plant where it will leach to the roots. Once absorbed by the foliage, stem, or roots, picloram is transported throughout the plant. Herbicides containing picloram are sold under a variety of brand names. Dow Chemicals and now Dow AgroSciences sell herbicides containing it under the brand name Tordon. During the Vietnam War, picloram and other herbicides were combined to make Agent White (commercially available as Tordon 101) and enhanced Agent Orange, which was previously used by the British military during the Malayan Emergency. Large quantities of these herbicides were sprayed by U.S. forces in areas where they considered its long-term persistence desirable, such as inland forests. In 1974, 413,000 pounds (187 t) of picloram were used in the U.S., mainly by government and industry.

Web Search Results

• [PDF] Picloram - USDA Forest Service

  picloram range from 0.125 to 1 lb a.e./acre. 17 Typically, the Forest Service uses rates in the lower part of this range and, based on Forest 18 Service use statistics, some applications may be below the lower bound of the labeled rates. 19 2.2. Chemical Description and Commercial Formulations 20 Picloram is a systemic herbicide that is registered for the post-emergent control of broadleaf 21 weeds and woody plants. Picloram was developed in the early 1960s by Dow Chemical 22 Company (Hamaker et al. 1963; Tomlin 2004). 23 24 Picloram is the common name for 4-amino-3,5,6-trichloropicolinic acid. As illustrated in 25 Figure 1, picloram is a pyridine carboxylic acid, a class of herbicides including aminopyralid, 26 clopyralid, fluroxypyr, and triclopyr. Structurally, picloram is most closely [...] is a herbicide used in the control of a number of broadleaf weeds and undesirable 3 brush. Picloram is used in Forest Service programs primarily for the control of noxious weeds. 4 Tordon K and Tordon 22K are the formulations of picloram currently used by the Forest Service. 5 Both formulations are produced by Dow AgroSciences as a liquid containing the potassium salt 6 of picloram. Technical grade picloram also contains low concentrations of hexachlorobenzene. 7 Hexachlorobenzene is classified as a carcinogen, and the carcinogenic risks associated with 8 applications of picloram are considered quantitatively in this risk assessment. 9 10 Workers are not at substantial risk from exposures to either picloram or hexachlorobenzene— 11 i.e., all of the upper bound HQs are less than 1 at the [...] (24.4% w/v). This is 7 equivalent to a concentration of 2 lb a.e./gallon. The remaining 75.6% of the formulation 8 consists of inerts, including a polyglycol polymer. Very little information is available on the 9 polyglycol polymer. Technical grade picloram also contains low concentrations of 10 hexachlorobenzene. Hexachlorobenzene is classified as a carcinogen and the carcinogenic risks 11 associated with applications of picloram are considered quantitatively in the current risk 12 assessment. 13 14 The most common application methods for Tordon involve backpack (selective foliar), boom 15 spray (broadcast foliar), and aerial applications. Mist blower application of picloram is not 16 permitted. The labeled application rates for picloram range from 0.125 to 1 lb a.e./acre. 17 Typically,

• [PDF] Picloram C hemicalWatch Factsheet - Beyond Pesticides

  Picloram chemicalWATCH Stats: Chemical Class: Pyridinecarboxylic acid Use: Feed crops, nonfood crops (including rights-of-way), forestry Toxicity Rating: Slightly toxic Signal Word: Caution Health Effects: Liver and kidney effects. Contains the contaminants; hexachlorobenzene (probable human carcinogen – Group B2) and nitrosamines. Environmental Effects: Moderately toxic to fish and slightly toxic to aquatic invertebrates. Extremely persistent in soil. Very high potential to leach to groundwater. High water solubility and high mobil-ity through soil. Picloram (4-amino-3,5,6-trichlo-ropicolinic acid) is a systemic, per-sistent herbicide used for broadleaf weed and woody plant control, es-pecially on rights-of-way. Produced by Dow Chemical Co. since 1963, this pesticide both by itself, and in [...] Picloram is considered by EPA to be moderately toxic to fish, al-though most studies have found it to be relatively non-toxic to birds, aquatic invertebrates, and bees. EPA’s Registration Standard on pi-cloram stated, “that low concentra-tions will adversely affect the rate of yolk sac absorption and growth of [lake trout] fry.” Update, November 2007: Picloram and its three main derivatives (picloram triisopropanolamine salt, isooctyl picloram, and potassium picloram) were reregistered in 1995 by the EPA as “Restricted Use Pesticides” based on the haz-ards to non-target plants and can only be applied by certified applicators. There are no residential uses for picloram. The EPA classifies picloram as a Group E carcinogen - evidence of non-carcinogenicity, how-ever it is structurally similar to [...] Picloram is ab-sorbed through leaves and roots, and circulates throughout plants, so that it is not possible to wash off residues. It poisons plants by re-placing the plant growth hormone indoleacetic acid in new growth, where it accumulates. Picloram kills by inhibiting protein synthesis in the plant so that it cannot make new tissues. However, most grasses are resistant to picloram. A 4:1 mixture of 2,4-D and picloram herbicides was used as a jungle defoliant in Viet Nam, where it was known as Agent White.

• [PDF] Developing ionic liquid forms of picloram with reduced negative ...

  As an auxin-type herbicide, picloram (4-amino-3,5,6-trichloropyridine-2-carboxylic acid) is widely used for controlling broad-leaved weeds in corn, wheat, pasture, pinus, sorghum and sugar cane (Massaroppi et al., 2003; Fairchild et al., 2009). It is a weak acid (pKa = 2.3) and usually marketed as potassium salt (Celis et al., 2002). The picloram acid water solubility is 560 mg L−1, while its potas-sium salt is 400, 000 mg L−1 (Mayes and Dill, 1984; U.S.EPA, 1995). Be-cause of its highly water-soluble and anionic characters, picloram displays low sorption on soil particles (Koc = 3–53 mL g−1) (Bovey and Richardson, 1991; Oliveira et al., 2013; Steffens et al., 2015), and its major route of dissipation is leaching (U.S.EPA, 1995; Close et al., 1998). When picloram was applied on soil at an [...] 2. Material and methods 2.1. Materials 2.1.1. Chemicals Picloram (96% purity) was purchased from Sichuan Lier Chemical Co., Ltd. Methanol, acetic acid, calcium chloride, sodium hydroxide, isopropylamine, octylamine, octadecylamine, 1-methylimidazole, and 4-methylmorpholine were analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd. (Beijing, China). Acetonitrile and methanol that were high-performance liquid chromatography (HPLC) grade were supplied from J. T. Baker (Phillipsburg, NJ, USA). Ul-trapure water was collected in the laboratory by using a Millipore water purification system (Millipore, Billerica, MA, USA). Picloram potassium (PP) was prepared based on acid–base reaction in our laboratory. [...] Developing ionic liquid forms of picloram with reduced negative effects on the aquatic environment Gang Tang, Baitao Wang, Guanglong Ding, Wenbing Zhang, You Liang, Chen Fan, Hongqiang Dong, Jiale Yang, Dandan Kong, Yongsong Cao ⁎ College of Plant Protection, China Agricultural University, Beijing, China H I G H L I G H T S • Five novel herbicidal ionic liquids (HILs) based on picloram were synthesized and characterized. • The HILs exhibited moderate adsorption capacity and low leaching characteristic. • The negative effects of picloram on the aquatic environment were reduced. • A lower use dosage of picloram was achieved by application of HIILs.

• [PDF] US EPA - Pesticides - Fact Sheet for Picloram

  Use Profile Picloram is a systemic herbicide used to control deeply rooted herbaceous weeds and woody plants in rights-of-way, forestry, rangelands, pastures, and small grain crops. It is applied in the greatest amounts to pasture and rangeland, followed by forestry. Picloram acid is a manufacturing use product with no end uses. The TIPA-salt and K-salt have food and feed uses, and are applied pre- or post-emergence as a ground or aerial broadcast or spot treatment. The IOE derivative is registered for non-food uses only. Picloram products have no household or residential uses. [...] Picloram is extremely mobile. Nearly 100% of the chemical leached but none of it degraded over a three-year period in a University of Arkansas study. Given its high persistence, it appears unlikely that picloram will degrade once it reaches ground water, even over a period of several years. Environmental Fate Assessment Picloram is among the most mobile of currently registered pesticides. In some soils, it is nearly recalcitrant to all degradation processes. Picloram has been detected in ground water in 10 states, to date. However, it generally does not pose a threat to human health at the levels detected. [...] Human Health Assessment Toxicity In studies using laboratory animals, picloram generally has been shown to be of moderate to low acute toxicity. Picloram and its derivatives are only slightly toxic by the oral and dermal routes and have been placed in Toxicity Categories III and IV (the lowest of four categories) for these effects. However, picloram acid is highly toxic and the three derivatives are moderately toxic by the inhalation route (Toxicity Categories I and II). Picloram and derivatives cause moderate eye irritation (Toxicity Category III). Most are not skin irritants (Toxicity Category IV, except IOE in Category III). The three derivatives are skin sensitizers while picloram acid is not.

• Picloram vs Triclopyr: Which One Should You Use? - POMAIS Agriculture

  ## What Is Picloram and How It Works Picloram is a systemic herbicide classified under the pyridine carboxylic acid family, known for its deep-rooted, long-lasting control of broadleaf weeds and woody plants. Once absorbed through the leaves or roots, Picloram translocates throughout the plant’s vascular system, eventually concentrating in active growth areas like meristems and roots. This systemic action disrupts plant hormone balance, leading to uncontrolled growth, tissue damage, and death. Picloram is particularly effective in non-crop areas, such as: [...] ## When to Choose Picloram While Triclopyr shines in selective and short-term applications, Picloram is unmatched when you need aggressive, long-lasting control of deep-rooted perennial weeds and woody plants in unmanaged or non-crop areas. Here’s when Picloram is the superior choice: ### 1. Long-Term Brush and Woody Weed Suppression Picloram provides residual control that can last 12 months or longer, making it ideal for: If regrowth is not acceptable—or if annual reapplication is not cost-effective—Picloram delivers the longevity you need. ### 2. Control of Difficult Invasive Species Picloram is especially potent against deep-rooted, tough-to-kill species such as: These species often resist foliar-only herbicides but succumb to Picloram’s root-translocating action.