Uptake and metabolism of hexazinone in <i>Rubus hispidus</i> L. and <i>Pyrus melanocarpa</i> (Michx.) Willd

Jensen, K. I. N.; Kimball, E. R.

doi:10.1111/j.1365-3180.1990.tb01685.x

Cited by 6 publications

(2 citation statements)

References 15 publications

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“…were less than 20% of that detected of the parent compound 8 DAT (Martin et al, 1981). The level of metabolites of hexazinone in the leaves of susceptible plant species Rubus hispidus L. 2 DAT were less than 20% of the detected level of the parent compound (Jensen and Kimball, 1990). The level of metabolites in leaves and leaf litter of a woody plant species, Saskatoon berry (Amelanchier alnifolia Nutt.…”

Section: Resultsmentioning

confidence: 98%

Herbicide residues in leaves of Erythroxylvm coca var coca plants treated with soil-applied tebuthiuron and hexazinone

Lydon

Darlington²

1998

J. of Env. Sc. & Hlth., Part B

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The herbicide residue levels in leaves of Erythroxylum coca var. coca Lam. plants treated with soil applications of tebuthiuron and hexazinone at 3.36 and 6.72 kg a.i. ha-1 were determined in order to estimate the potential for human exposure to these residues from consuming the leaves or cocaine produced from them. Field-grown plants were treated with a commercial formulation of tebuthiuron or hexazinone and leaves were harvested at the first indication of herbicide injury (i.e. chlorosis and/or necrosis) and at the onset of leaf abscission. Herbicide residues were detected by HPLC in leaf samples from both harvests of all plants treated with tebuthiuron or hexazinone. At 3.36 kg ha-1, herbicide residues in the leaves were less than 2 micrograms g-1 dry wt. for both harvests of both experiments. The highest residue levels detected were 5.90 micrograms g-1 dry wt. for tebuthiuron and 7.17 micrograms g-1 dry wt. for hexazinone in leaves from plants treated with the herbicide at the rate of 6.72 kg ha-1 and harvested at the onset of leaf drop. Based on published toxicity data and estimates of leaf consumption, the herbicide residues in leaves of E. coca var. coca plants treated with tebuthiuron or hexazinone at twice the recommended control rates or less would have a negligible contribution to the health risks of individuals who chew coca leaves. Furthermore, based on the most conservative estimates of cocaine yield and herbicide carry over, death by cocaine overdose would occur long before the NOEL for either herbicide was reached.

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Section: Resultsmentioning

confidence: 98%

Herbicide residues in leaves of Erythroxylvm coca var coca plants treated with soil-applied tebuthiuron and hexazinone

Lydon

Darlington²

1998

J. of Env. Sc. & Hlth., Part B

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“…This results in a build-up of triplet state chlorophyll which generates singlet oxygen (Dodge, 1982) that peroxidize cell membrane lipids and the affected plant dies from oxidative stress (Balke, 1987;Bartels, 1987). Some species can metabolize the compound before it reaches the chloroplasts (McNeil et al, 1984;Jensen and Kimball, 1990), thereby imparting some degree of tolerance. While blueberries are fairly tolerant (Zutter and Zedaker, 1988), oaks, sweetgum (Liquidambar styraci¯ua) and sumac (Rhus spp.)…”

Section: Site History and Experimental Treatmentsmentioning

confidence: 99%

Restoring longleaf pine wiregrass ecosystems:

Brockway

Outcalt

2000

Forest Ecology and Management

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A longleaf pine wiregrass ecosystem in the sandhills of north central Florida, upon which turkey oak gained dominance following a wild®re, was treated with applications of hexazinone (1.1 or 2.2 kg/ha) in May 1991. All applications successfully reduced competition from oaks in the overstory and understory (mortality >80%), resulting in progressive increases in the foliar cover of wiregrass, all graminoids and forbs through time. Broadcast application caused a decline in forb cover and species richness during the initial growing season, which recovered by the following year. The 2.2 kg/ha spot application resulted in an increase in species richness, while evenness declined with the continuing expansion of wiregrass. The entire site was then burned in June 1995 by prescribed ®re, which caused a widespread decrease in the cover of oaks, shrubs, wiregrass, all graminoids and forbs and plant species richness. In the following year, forb cover increased and oak cover remained signi®cantly lower on plots treated with the combination of hexazinone plus ®re than on ®re-only plots. The overall cover of forbs, graminoids, shrubs and longleaf pines continued to increase through time. Broadcast application initially exposed a greater number of understory plants to direct contact with herbicide, posing a higher mortality risk than may be acceptable in restoration efforts. Although recovery occurred in subsequent years, the lower selectivity of broadcast application makes it a less suitable restoration technique. Spot application of hexazinone was more selective in its effects upon the plant community. The 2.2 kg/ha spot application produced increases in the cover of wiregrass, all graminoids and forbs and the highest levels of species richness and diversity. The 2.2 kg/ha application rate was also most effective in controlling woody plant competition and is therefore recommended for restoring longleaf pine wiregrass ecosystems in sandhills and similar environments. Hexazinone application followed by prescribed ®re accelerates the rate of ecosystem restoration over that achievable by using ®re alone. The ecological bene®ts of controlling competition and rebalancing¯oristic composition rapidly achieved through this combination of treatments would likely require many cycles of prescribed ®re, if used as an individual treatment, over a period of several decades.

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