Mulch and Hexazinone Herbicide Shorten the Time Longleaf Pine Seedlings are in the Grass Stage and Increase Height Growth

Abstract

Herbaceous plant control with mulch or hexazinone herbicide influenced planted longleaf pine (Pinus palustris Mill.) seedling total height on a silt loam site in central Louisiana. The site had been sheared and windrowed in 1991, and rotary mowed before three treatments were established in a randomized complete block design: (1) untreated check: no herbaceous plant control after planting; (2) five mulches: on each plot, five randomly assigned mulches were placed around seedlings; the mulches were either a mat of cotton, hemlock and polyester, pine straw, woven polypropylene, or perforated polyethylene; and (3) hexazinone: the herbicide hexazinone at 1.12 kg active ingredient/ha was annually sprayed in the first two growing seasons over the rows of unshielded seedlings. The longleaf seedlings were planted in February 1993.

After three growing seasons, seedlings on the mulch and hexazinone treatments were taller than those on the check plots. About 59 percent of the mulched and hexazinone treated seedlings had grown out of the grass stage (at least 12 cm tall), compared to 17 percent of the check seedlings. After five growing seasons, the percentage of longleaf pine seedlings out of the grass stage was similar on all treatments and averaged 87 percent. However, these better growing pines were taller on the mulch and hexazinone treatments (a 142-cm average) than on the checks (78 cm). Pine straw was an ineffective mulch, probably because the straw smothered the seedlings. The longleaf saplings were tallest when the perforated polyethylene mat was used.

Keywords

Pinus palustris Mill, loblolly pine, P. taeda, plantation establishment, competition control, vegetation management

Citation

Haywood, James D. 2000. Mulch and Hexazinone Herbicide Shorten the Time Longleaf Pine Seedlings are in the Grass Stage and Increase Height Growth. New Forests, 19:, pp. 279-290