Pitch × loblolly pine hybrid response to competition control and associated ice damage

Abstract

Growth response to three levels of competing vegetation control were compared in planted loblolly pine ( Pinus taeda) and pitch × loblolly pine ( Pinus rigida × P. taeda) F2 hybrids. 1-0 seedlings of both seedlots were planted on cutover sites on the Virginia (USA) Appalachian Piedmont Plateau and were subjected to no competition control, herbaceous weed control, or combined herbaceous and woody control. Loblolly pine consistently outperformed hybrids on these sites. Combined vegetation control increased stem volume of hybrids and loblolly pine 54% and 47% compared to no control, respectively. Hybrids had 23% greater stem volume in response to herbaceous control while loblolly pine did not respond to this treatment. Hybrids grown under the combined woody and herbaceous vegetation control treatments were damaged by ice more frequently than any other seedlot–vegetation control treatment combination. These results suggest that pitch × loblolly hybrid offspring and loblolly pine differ in stem volume growth response to weed control treatments, necessitating the development of specific silvicultural strategies for the intensive management of hybrid pines.