Hexazinone dissipation in forest ecosystems and impacts on aquatic communities

Michael, Jerry L.; Webber, E. Cliff; Bayne, David R.; Fischer, Joseph B.; Gibbs, Hilliard; Seesock, Wendy C.

doi:10.1139/cjfr-29-7-1170

Cited by 7 publications

(18 citation statements)

References 0 publications

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“…Triclopyr has been found to move to depths of 10-30 cm (Lee et al, 1985, Stephenson et al, 1990. Hexazinone, perhaps the most studied non-phenoxy forestry herbicide, has been detected at depths down to 75 cm, but more commonly is not detected below about 50 cm (Roy et al, 1989, Feng and Navratil 1990, Allender 1991, Michael et al, 1999. Imazapyr is rarely detected at 50 cm, but is known to move below 30 cm in several soil types (Rahman et al, 1993).…”

Section: Leaching Through the Soil Profilementioning

confidence: 99%

“…Overland flow occuring shortly after herbicide application potentially contains very high concentrations of herbicide which it carries to streams. Because of its short residence time prior to entry into streams, overland flow results in higher levels of stream contamination than that observed from herbicide which has leached through the soil profile and entered streams through baseflow (Michael and Neary, 1993;Michael et al, 1999;.…”

Section: Leaching Through the Soil Profilementioning

confidence: 99%

“…While herbicides are mobile in soil, little lateral movement has been observed through the soil profile following infiltration. Downslope movement of herbicides occurs principally in the form of overland flow or macropore flow (Michael et al, 1989, Michael et al, 1990, Michael and Neary, 1991Michael et al, 1999;Bastardie et al, 2002, Buttle andMcDonald, 2002). Overland flow is a function of antecedent soil moisture conditions, precipitation rate, infiltration rates, and drainage capacity, but occurs to some extent any time the instantaneous precipitation rate exceeds the infiltration rate.…”

Section: Stream Contamination During Application and Storm Runoffmentioning

confidence: 99%

“…This study used by the USEPA for hexazinone reregistration was conducted by the U.S. Forest Service in Coosa County, Alabama, U.S.A. (Michael et al, 1999). The study conducted from 1990-1992 utilized a 290 ha portion of the Hatchet Creek drainage and included 3 watersheds, two treated and one untreated control.…”

Section: Coosa County Hexazinone Studymentioning

confidence: 99%

“…Benthic macroinvertebrate diversity, population numbers, and trophic level function were unaffected by hexazinone treatment. The six principal metabolites of hexazinone were also monitored, but were not of significant concentrations in any samples analyzed (Michael et al, 1999).…”

Section: Coosa County Hexazinone Studymentioning

confidence: 99%

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Best Management Practices for Silvicultural Chemicals and the Science Behind Them

Michael

2004

Water, Air, & Soil Pollution: Focus

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Abstract. Silvicultural chemicals include fertilizers and pesticides applied for forest management. All states east of the Rockies have at least some form of silvicultural chemical best management practices (SCBMPs) and it is widely accepted that SCBMPs effect some protection of water quality. All SCBMPs recommend handling and application precautions and a minimum width streamside management zone (SMZ) on each side of streams for protection of water quality and aquatic ecosystems. Typically these zones increase in width as stream width increases. In areas where cold-water fish are present, additional widths are designated for their protection. Minimum SMZ widths range from 8 to 91 meters on each side of the stream bank for intermittent and perennial streams. Most SMZ recommendations do not cover ephemeral drainages, ditches or canals. SMZs are generally described as being site specific with width dependent on slope, soil type and other conditions as well as the stream's designation as perennial or intermittent. The science behind SCBMPs is often elusive. Spray drift can be controlled through proper selection and use of application technology while considering site specific conditions. SMZs greatly reduce the amount of herbicides reaching streams. Available toxicological data and research on aquatic ecosystem impacts from herbicide use suggest that additional protection from silvicultural chemicals may not be necessary. However, there is evidence to suggest that protection of ephemeral and intermittent channels can further reduce entry of silvicultural chemicals into streams and also reduce sedimentation. This may be the most fruitful area of research we can pursue in light of the knowledge gaps listed.

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Section: Leaching Through the Soil Profilementioning

confidence: 99%

Section: Leaching Through the Soil Profilementioning

confidence: 99%

Section: Stream Contamination During Application and Storm Runoffmentioning

confidence: 99%

Section: Coosa County Hexazinone Studymentioning

confidence: 99%

Section: Coosa County Hexazinone Studymentioning

confidence: 99%

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Best Management Practices for Silvicultural Chemicals and the Science Behind Them

Michael

2004

Water, Air, & Soil Pollution: Focus

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Effects of the herbicide imazapyr on benthic macroinvertebrates in a logged pond cypress dome

Fowlkes

Michael

Crisman

et al. 2003

Enviro Toxic and Chemistry

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Increased herbicide use in silviculture over the last several decades has led to concern over potential water contamination, which may affect biotic health. In the southeastern United States, pine flatwoods are important for timber production and are often interspersed with cypress wetlands. Cypress domes are isolated, shallow basins that collect surficial waters from adjacent forested areas and therefore might be expected to contain pesticide from storm runoff. This study utilizes in situ microcosm experiments to assess the effects of a concentration gradient of the herbicide imazapyr (0.184, 1.84, and 18.4 mg/L, equivalent to 1, 10, and 100 times the expected environmental concentration from a normal application rate) on the macroinvertebrate community of a logged pond cypress dome using changes in macroinvertebrate composition, chironomid biomass, and chironomid head-capsule deformities. The control core was not significantly different from the surrounding cypress dome for any parameter, suggesting that enclosure effects were likely of minimal importance in the final experimental results. The lack of statistical difference (p < 0.05) in macroinvertebrate community composition, chironomid deformity rate, and chironomid biomass between treatments suggests that imazapyr did not affect the macroinvertebrate community at the concentrations tested. Chironomid deformity rate ranged from 0.97% for imazapyr control to 4.96% for the 100x treatment, with chironomid biomass being 1.79 and 1.87 mg/L, respectively.

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Charcoal root dip and controlled release carrier effects on hexazinone selectivity with sycamore (Platanus occidentalis) seedlings

Ramsey

Wehtje

Walker

et al. 2004

Forest Ecology and Management

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Hexazinone dissipation in forest ecosystems and impacts on aquatic communities

Cited by 7 publications

References 0 publications

Best Management Practices for Silvicultural Chemicals and the Science Behind Them

Best Management Practices for Silvicultural Chemicals and the Science Behind Them

Effects of the herbicide imazapyr on benthic macroinvertebrates in a logged pond cypress dome

Charcoal root dip and controlled release carrier effects on hexazinone selectivity with sycamore (Platanus occidentalis) seedlings

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