Abstract Results at 30 years in southeastern Louisiana plantations of four species of pines showed that genotypes (either species or seedling grades), spacings, and soils consistently and materially affected survival, growth, and yield, and sometimes incidence of disease. (Root pruning, type of planting tool, and exact date of planting had, by contrast, negligible effects on any variable observed.) Slash and loblolly pines outyielded longleaf and shortleaf but were far more susceptible to fusiform rust. In all four species, wide spacings excelled close spacings, and Grade 1 slash and loblolly seedlings significantly excelled Grade 3 seedlings, except that neither spacing nor grade affected degree of rust infection. Growth tended to be poorer on Myatt very fine sandy loam than on four better-drained soils.
Philip C. Wakeley (Tue,) studied this question.