Early Field Growth of Loblolly Pine Rooted Cuttings and Seedlings

Abstract

Early growth and fusiform rust resistance of loblolly pine (Pinus taeda L.) rooted cuttings and seedlings from the same nine full-sib families established on two sites (Nassau Co., FL and Monroe Co., AL) were compared.Although site effects on growth were large, height, diameter and volume growth of the rooted cuttings and seedlings did not differ through the first six growing seasons in the field (with the exception of first year height growth at the Florida site). Fusiform rust (caused by Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme [Cumin.] Burds. et Snow) incidence at age 6 yr was significantly lower in the rooted cuttings than the seedlings at both the Florida site (15.6 versus 22.3%, respectively) and the Alabama site (46.0 versus 51.0%, respectively). In addition, correlations of full-sib family performance between (1) rooted cuttings and seedlings and (2) rooted cuttings and seedling progeny test data were positive, statistically significant and moderate to high for both growth traits and fusiform rust incidence. Thus, families or individual trees selected from seedling genetic tests in existing tree improvement programs should also perform well as rooted cuttings. These results and those from similar studies indicate that field performance of loblolly pine rooted cuttings derived from seedling hedges should not be a concern. Large-scale propagation using rooted cuttings will deliver predicted gains from the selection and deployment of elite full-sib families and clones. In addition, the use of rooted cutting planting stock may offer a further reduction in fusiform rust incidence.