Growth of Loblolly Pine Treated With Hexazinone, Sulfometuron Methyl, and Metsulfuron Methyl For Herbaceous Weed Control

Author： Michael J. L.

Publisher： Society of American Foresters

ISSN： 0148-4419

Source： Southern Journal of Applied Forestry, Vol.9, Iss.1, 1985-02, pp. : 20-26

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Abstract

Aerial application of 0.25 pounds active ingredient per acre of sulfometuron methyl [Oust(TM), formerly DPX-5648] or 2.0 pounds of hexazinone [Velpar L (TM)] postemergent in May 1982, resulted in good weed control. Weeds controlled on the silty clay coastal plain soil included pokeweed (Phytolacca americana L.), ragweed (Ambrosia sp.), goldenrod (Solidago sp.), and evening primrose (Oenothera sp.). Growth of 1-year-old loblolly pine (Pinus taeda L.) seedlings released with sulfometuron methyl or hexazinone was significantly improved in comparison to untreated seedlings. No significant pine mortality was associated with either treatment. On similar sites where blackberry (Rubus sp.), honeysuckle (Lonicera japonica Thunberg), and herbaceous weeds are the major problem, application of sulfometuron methyl from pre-emergence to the postemergent stage (when weeds are up to 12 to 18 inches in height) is recommended. Hexazinone is recommended as a postemergent treatment for herbaceous weed control. Treatment with metsulfuron methyl (formerly DPX-T6376-21) did not result in any growth responses significantly greater than untreated seedlings. Impacts of deer browsing on seedlings resulted in a slight height reduction the first and second growing seasons following planting but by the end of the third growing season browsed seedlings had made up the difference. No diameter differences were associated with deer browsing at any time during the study.