The objective of this study was to identify effective herbicide treatments for the release of loblolly pine (Pinus taeda L.) from competing hardwoods 7 yr after treatment. The study site was a hardwood-to-pine conversion area that had been chopped and burned. Treatments included two groups of herbicides: (1) imazapyr at 1.0 lb ae/ac used alone or in combination with metsulfuron or glyphosate, and (2) glyphosate at 1.5 lb ae/ac used alone or in combination with metsulfuron. Broadcast herbicide treatments were applied in September, 1985, during the second growing season. All treatments were effective in controlling hardwoods, with the least effective treatment decreasing hardwood basal area by 55% relative to the untreated check. The pine crop trees responded with increased diameter, height, basal area, and volume. The increase in total pine volume outside bark over the untreated check ranged from 163 to 640 ft³/ac (22% to 85%) and the increase in pine basal area ranged from 13 to 40 ft²/ac (27% to 83%). No treatment resulted in significant pine mortality. Although pine height growth was stunted the year following treatment, at age 9, mean height gains on treated plots ranged from 2.7 ft to 5.6 ft. Treatments containing imazapyr performed better than treatments with glyphosate alone or in combination with metsulfuron. Imazapyr at 1.0 lb ae/ac reduced hardwood basal area to 2 ft²/ac at age nine compared to 25 ft²/ac on the untreated check plots. There was, therefore, little room for improvement from additives, indicating that combinations with lower rates of imazapyr, comparable to today' s operational rates, may be more appropriate. South. J. Appl. For. 20(4):177-181.
Document Type: Journal Article
School of Forestry and Alabama Agricultural Experiment Station, Auburn University, AL 36849-5418
Publication date: November 1, 1996
More about this publication?
Each regional journal of applied forestry focuses on research, practice, and techniques targeted to foresters and allied professionals in specific regions of the United States and Canada. The Southern Journal of Applied Forestry covers an area from Virginia and Kentucky south to as far west as Oklahoma and east Texas.