Effects of Nursery Characteristics on Field Survival and Growth of Loblolly Pine Rooted Cuttings

Morphological characteristics of rooted cuttings and seedlings of four open-pollinated loblolly pine families cultured at the G.H.W. Weyerhaeuser Nursery near Washington, North Carolina were assessed after lifting. Cuttings were visually assigned to nine grading classes and six putative cull classes. The nine grading classes represented a factorial of three root collar diameter classes (small [4–6 mm], medium [6–8 mm] and large [8–10 mm]) and three root quality classes (poor, fair, and good). Putative cull classes included runts, poor foliage coverage, jumbos, “dog-legged” (one horizontal root at a right angle to the stem), multiple leaders, and excessive sweep. After assessment, the rooted cuttings and seedlings were established in a randomized block design on a coastal site in southern Beaufort County, North Carolina. Five years after establishment in the field, survival, height, diameter, presence or absence of fusiform rust incidence, number of leaders, and sweep were assessed. Analyses of variance were conducted to detect differences among the putative cull classes. Nursery rooting cutting morphological traits were regressed on fifth year field traits. Iterative logistic regression was performed between the nursery traits (continuous variables) and survival (binary variable). Overall, fifth year survival of the rooted cuttings was higher than that of the seedlings (77 versus 42%, respectively), and their stem volume was not significantly different from seedlings (0.259 versus 0.285 m3). For the four open-pollinated families studied, these results indicate that no culling standards are needed for rooted cutting planting stock to perform at least as well as seedling planting stock. However, eliminating cuttings with poor foliage coverage (less than 2.5 cm) and culling or pruning rooted cuttings with multiple leaders is recommended to reduce the number of forked trees in the field. South. J. Appl. For. 26(4):207–213.