Growth of Loblolly Pine Treated With Hexazinone, Sulfometuron Methyl, and Metsulfuron Methyl For Herbaceous Weed Control
Aerial application of 0.25 pounds active ingredient per acre of sulfometuron methyl [Oust(TM), formerly DPX-5648] of 2.0 pounds of hexazinone [Velpar L. (TM)] postmergent in May 1982, resulted in good weed control. Weeds controlled on the silly clay coastal plain soil included pokweed (Phytolacca americana L.) rugweed (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 treament. On similar sites where blackberry (Rubus sp.), honeysuckle (Lonicera japonica Thumberg), and herbaceous weeds are the major problem, application of sulfometuron methyl from per-emergence to the postmergent stage (when weeds are up to 12 to 18 inches in height) is recommended. Hexazinone is recommended as a postmergent treatement for herbaveous weed control. Treament with metsulforon methyl (formerly DPX-T6376-21) did not result in any growth responses significantly greater that untreated seedlings. Impacts of deer browsing on seedlings resulted in a slight height reduction the firest 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 the deer browsing at any time during hte study.