Association Between Fusiform Rust Incidence and CRIFF Soil Classification for Slash Pine Plantations in the Coastal Plain of Florida and Georgia

Abstract The association between fusiform rust incidence in young slash pine plantations and the CRIFF (Cooperative Research in Forest Fertilization) soil classification system in the Coastal Plain of Florida and Georgia was examined in two independent data sets: (1) 958 predominantly 5-year-old plantations from an industrial forest inventory and (2) 73 9-to-13-year-old plantations in a CRIFF research study. Rust incidence was calculated as the percentage of living trees with a branch or stem gall. Soils were classified into six groups (A-F) according to soil drainage and the nature of and depth to the B horizon. A third data set relates oak (alternate host) abundance to soil groups in 53 plantations. Overall, the very poorly to moderately well-drained CRIFF C and D group soils (flatwoods Spodosols) exhibit the lowest rust incidence (ẋ = 5.9% and 5.3%); the moderately well- to well-drained E and F group soils (Inceptisols and Ultisols) have the highest rust incidence (ẋ = 45.2% and 28.5%); and the poorly to somewhat poorly drained A and B soils (Ultisols, Entisols, and Inceptisols) are intermediate in rust incidence (ẋ = 18.4% and 16.5%). Oak abundance varied significantly within and among soil groups. In general, oaks were more abundant on E and F soils than on B and C group soils. CRIFF soil groups are useful to characterize regional rust incidence, but are not associated with rust incidence in individual plantations. Plantations of like soil groups exhibit high or low rust incidence depending on the mean rust incidence of the area in which they occur. South. J. Appl. For. 14(1):39-43.