Epicormic Branching in Red Oak Crop Trees Five Years after Thinning

INTRODUCTION Epicormic branches are shoots arising spontaneously from adventitious or dormant buds on stems or branches of woody plants, often following exposure to increased light levels or fire (Helms 1998). Epicormic branches are considered defects on tree boles because they result in undesirable knots on trees, reducing the monetary value of logs and lumber (Stubbs 1986). U.S. Department of Agriculture Forest Service factory log grade guidelines indicate that the size of the epicormic branch, in addition to the number and location of epicormic branches on the log, is important in determining log grades (Rast and others 1973). If an epicormic branch is > 3/8 inch in diameter at the point of origin on the log surface, then it is counted as a full defect; an epicormic branch ≤ 3/8 inch in diameter is only counted as a one-half defect on logs ≥ 14 inches in scaling diameter (Rast and others 1973). Theoretically, even a single, large epicormic branch ideally positioned on a small log can reduce the grade of the log. Meadows and Burkhardt (2001), in a case study using willow oak (Quercus phellos L.) logs, showed that as few as five epicormic branches on a 16-foot log reduced the log grade of trees with an average diameter at breast height (d.b.h.) of 19.1 inches. They also showed that epicormic branches developing on willow oak boles after partial cutting reduced willow oak log grades by 50 percent. The value of the lumber from these logs was reduced 13 percent due to surface knot defects caused by the epicormic branches.