Thinning To Improve Growth And Control The Canker Decay Fungus Inonotus Hispidus In A Red Oak-Sweetgum Stand In The Mississippi Delta

Thinning was applied to a 55-year-old, red oak-sweetgum (Quercus spp.Liquidambar styraciflua L.) stand in the Delta region of western Mississippi in late summer 1997. The thinning operation was a combination of low thinning and improvement cutting to remove most of the pulpwood-sized trees as well as sawtimber-sized trees that were damaged, diseased, of poor bole quality, or of an undesirable species. Special emphasis was placed on removing all red oaks infected with Inonotus hispidus, a canker decay fungus that causes serious degrade and cull, especially in willow oak (Quercus phellos L.) and water oak (Q. nigra L.). Prior to thinning, stand density averaged 98 trees and 125 square feet of basal area per acre. Quadratic mean diameter was 15.4 inches, while stocking averaged 102 percent across the study area. Thinning reduced stand density to 32 trees and 59 square feet of basal area per acre, increased quadratic mean diameter to 18.4 inches, and reduced stocking to 47 percent. Thinning also increased the red oak component of the stand from 47 percent of the basal area prior to thinning to 59 percent of the basal area after thinning. There has been little stand-level growth during the first 3 years following the thinning operation. Thinning significantly increased diameter growth of residual trees, especially red oaks, but has not yet produced a significant increase in quadratic mean diameter. Even trees in the dominant crown class experienced increased diameter growth as a result of the thinning operation. Epicormic branching varied widely between species groups. Thinning had no significant effect on epicormic branching in red oaks, but greatly increased the production of new epicormic branches in sweetgum. Three years after thinning, epicormic branches were most numerous on low-vigor sweetgum trees in the lower crown classes. Most importantly, thinning had no effect on the production of epicormic branches along the boles of red oak crop trees. 1Principal Silviculturist and Principal Plant Pathologist, USDA Forest Service, Southern Research Station, Stoneville, MS.;Professor, Department of Entomology and Plant Pathology, Mississippi State University, Mississippi State, MS., respectively. Citation for proceedings: Outcalt, Kenneth W., ed. 2002. Proceedings of the eleventh biennial southern silvicultural research conference. Gen. Tech. Rep. SRS–48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 622 p.