Tenth-Year Results of Herbaceous Weed Control in a Loblolly Pine Plantation

Abstract

Abstract Herbaceous weed control influenced the growth of planted loblolly pine (Pinus taeda L.) over a 10-yr-period. Five treatments were examined: (1) Untreated control: seedlings were planted in the established herbaceous vegetation; (2) Glyphosate: glyphosate was broadcast in September 1981 before planting; (3) Disked: plots were cross-disked in September 1981 before planting; (4) Glyphosate-PPWC: glyphosate was broadcast before planting as in Treatment 2, and postplant weed control (PPWC) herbicides were broadcast yearly for 4 yr (1982, atrazine plus simazine ; 1983, atrazine plus oxyfluorfen; 1984 and 1985, hexazinone ); and (5) Disked-PPWC: plots were disked before planting as in Treatment 3, and the PPWC herbicides were broadcast as in Treatment 4. Four years of PPWC did not affect survival and resulted in greater height, dbh, and volume per loblolly pine through 10 growing seasons. The disked-PPWC plots were the most productive through 8 growing seasons, but higher than average mortality after 8 yr on the disked-PPWC treatment resulted in the glyphosate-PPWC plots producing more volume per acre after 10 growing seasons. Total volume production was 253 inside bark ft³/ac greater on the two PPWC treatments than on the untreated controls. South. J. Appl. For. 18(3): 105-109.