Fate of 3,6-dichloropicolinic acid in soils

Pik, Andrew J.; Peake, E.; Strosher, Melvin T.; Hodgson, G. W.

doi:10.1021/jf60213a011

Cited by 37 publications

(28 citation statements)

References 6 publications

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“…[5,12 -15] Warm, moist soils with high microbial activity lost clopyralid in relatively short period, whereas in sterile, dry, cold or waterlogged soils, the herbicide residues persisted for several months or even years. [12] Half lives of 13 -39 d were observed by Baloch-Haq et al [16] in five different soils from Germany and UK incubated at 40% WHC and 20°C. Smith and Aubin [13] examined persistence of clopyralid in three soils at different temperatures.…”

Section: Laboratory Studiesmentioning

confidence: 90%

“…It was much faster in non-sterlized soils (t 1/2 , 7.3 d) than in sterilized soil at 20°C (t 1/2 , 57.8 d). Pik et al [12] also found that disappearance in sterilized soils was very slow with only 28% of the herbicide decayed after 57 weeks. However, their dissipation rates in non-sterile soils were rather slow with only 30, 38, and 55% of the applied herbicide decomposed in three different soils after 9 week incubation.…”

Section: Laboratory Studiesmentioning

confidence: 96%

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Dissipation of the Herbicide Clopyralid in an Allophanic Soil: Laboratory and Field Studies

Ahmad

James

Rahman

et al. 2003

Journal of Environmental Science and Health, Part B

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Soil dissipation of the herbicide clopyralid (3,6-dichloropicolinic acid) was measured in laboratory incubations and in field plots under different management regimes. In laboratory studies, soil was spiked with commercial grade liquid formulation of clopyralid (Versatill, 300 g a.i. L(-1) soluble concentrate) @ 0.8 microg a.i. g(-1) dry soil and the soil water content was maintained at 60% of water holding capacity of the soil. Treatments included incubation at 10 degrees C, 20 degrees C, 30 degrees C, day/night cycles (25/15 degrees C) and sterilized soil (20 degrees C). Furthermore, a field study was conducted at the Waikato Research Orchard near Hamilton, New Zealand starting in November 2000 to measure dissipation rates of clopyralid under differing agricultural situations. The management regimes were: permanent pasture, permanent pasture shielded from direct sunlight, bare ground, and bare ground shielded from direct sunlight. Clopyralid was sprayed in dilute solution @ 600 g a.i. ha(-1) on to field plots. Herbicide residue concentrations in soil samples taken at regular intervals after application were determined by gas chromatograph with electron capture detector. The laboratory experiments showed that dissipation rate of clopyralid was markedly faster in non-sterilized soil (20 degrees C), with a half-life (t1/2) of 7.3 d, than in sterilized soil (20 degrees C) with t1/2 of 57.8 d, demonstrating the importance of micro-organisms in the breakdown process. Higher temperatures led to more rapid dissipation of clopyralid (t1/2, 4.1 d at 30 degrees C vs 46.2 d at 10 degrees C). Dissipation was also faster in the day/night (25/15 degrees C) treatment (t1/2, 5.4 d), which could be partly due to activation of soil microbes by temperature fluctuations. In the field experiment, decomposition of clopyralid was much slower in the shaded plots under pasture (t1/2, 71.5 d) and bare ground (t1/2, 23.9 d) than in the unshaded pasture (t1/2, 5.0 d) and bare ground plots (t1/2, 12.9 d). These studies suggest that environmental factors such as temperature, soil water content, shading, and different management practices would have considerable influence on rate of clopyralid dissipation.

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Section: Laboratory Studiesmentioning

confidence: 90%

Section: Laboratory Studiesmentioning

confidence: 96%

Dissipation of the Herbicide Clopyralid in an Allophanic Soil: Laboratory and Field Studies

Ahmad

James

Rahman

et al. 2003

Journal of Environmental Science and Health, Part B

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“…Because clopyralid is mainly decomposed biologically, 23) we examined the relationship between its rate of decomposition and the rate of oxygen consumption, which was high when the compost contained a large amount of biodegradable OM, owing to heightened activity of microorganisms. The rate of decomposition was highest when the rate of oxygen consumption was <5 mg/min/kg (Fig.…”

Section: Decomposition Of Clopyralid During Compostingmentioning

confidence: 99%

“…The half-life is stated to be from 14 to 56 days (d) in German guidelines and from 2 to 94 d in US guidelines. 18) That in clay, clay loam, and sandy loam soils ranged from 10 to 47 d under incubation at 10 to 30°C for 84 d. 22) In the ground, clopyralid is mainly decomposed by microorganisms, 23) and its half-life is shorter in unsterilized soil than in sterilized soil. 24) When clopyralid was sprayed onto various organic substrates (wheat straw chop, high moor peat, pine wood sawdust), 64 to 73% decomposed within the first 30 d. 25) However, according to the EPA, clopyralid can persist in soil with a half-life of up to 11 months.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of clopyralid herbicide during composting in small composting experiment units

2015

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Owing to its long persistence in the environment, residual clopyralid in compost has emerged as a problem worldwide. We mixed 9 kg by weight of dairy cow manure and 3 kg by weight of straw, and a clopyralid solution was added to each of three 3-kg aliquots until the clopyralid concentrations were 0, 6.7, and 20 mg/kg, respectively. To understand its fate during composting, the samples were composted in small composting experiment units for 77 days. Samples were collected at 7, 13, 18, 25, 32, 42, 57, and 77 days; each time, the composts were turned. Clopyralid was concentrated in the compost during primary fermentation and slowly decomposed during secondary fermentation. The ease of elution of clopyralid during composting shows that drainage must be managed during the composting of materials that might contain clopyralid.

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“…Picloram aerially sprayed at 1.1 kg ai ha (MacDiarmid 1977). Clopyralid can remain active for 60-420 days depending on the rate applied and environmental conditions (Pik et al 1977;Bovey and Richardson 1991;Cox 1998).…”

Section: Introductionmentioning

confidence: 99%

Relative persistence of commonly used forestry herbicides for preventing the establishment of broom (Cytisus scoparius) seedlings in New Zealand plantations

Trần

Harrington

Robertson

et al. 2015

N.Z. j. of For. Sci.

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Background: Many of the herbicides used in site preparation of forests and during initial selective weed management can persist in the soil for several months, killing or stunting seedlings of broom (Cytisus scoparius (L.) Link) as they establish. The objective of this research was to determine the relative persistence and effect over time of the herbicides most widely applied within radiata pine (Pinus radiata D.Don) plantations in New Zealand on broom survival and growth. Methods: Eleven herbicide treatments were applied in early summer to a Tokomaru silt loam soil. Soil samples were collected from each treatment at fortnightly intervals for up to a year. The samples were placed into pots and immediately sown with scarified viable broom seeds in a heated glasshouse. Relative growth and biomass of seedlings were determined as the ratio of growth and survival in each treatment relative to growth and survival in an untreated control. Logistic curves were fitted to recorded values of relative growth and survival over time and the time to reach 50 and 95% of the vigour of the plants in the untreated control was determined. Results: The treatments can be approximately ranked in the following order from most to least persistent: triclopyr/ picloram > high rate of clopyralid > high rate of hexazinone > terbuthylazine/hexazinone > low rate of hexazinone > low rate of clopyralid > high rate of terbuthylazine > triclopyr > high rate of metsulfuron-methyl > low rate of terbuthylazine > low rate of metsulfuron-methyl. Conclusion: As the rate of triclopyr/picloram used in this work is too phytotoxic to be used selectively over newly planted radiata pines, this treatment would only be suitable prior to tree planting so residual activity would control seedlings that develop after scrub clearance. For post-plant weed management operations, results show hexazinone and high rates of clopyralid to be useful for long-term management of broom as both these herbicides have low phytotoxicity to radiata pine. When combined with low rates of triclopyr and picloram, clopyralid could provide an effective treatment that could be used in combination with oversown or naturally occurring grasses to manage broom.

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Fate of 3,6-dichloropicolinic acid in soils

Cited by 37 publications

References 6 publications

Dissipation of the Herbicide Clopyralid in an Allophanic Soil: Laboratory and Field Studies

Dissipation of the Herbicide Clopyralid in an Allophanic Soil: Laboratory and Field Studies

Dynamics of clopyralid herbicide during composting in small composting experiment units

Relative persistence of commonly used forestry herbicides for preventing the establishment of broom (Cytisus scoparius) seedlings in New Zealand plantations

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