Temporal and Spatial Patterns of Fusiform Rust Epidemics in Young Plantations of Susceptible and Resistant Slash and Loblolly Pines. Robert A. Schmidt, Professor of Forest Pathology, USDA Forest Service, Southeastern Forest Experiment Station, School of Forest Resources and Conservation, University of Florida, Gainesville 32611. Renee C. Holley, Statistician I, Michael C. Klapproth, Graduate Student, Department of Forestry, and Thomas Miller, Research Plant Pathologist, USDA Forest Service, Southeastern Forest Experiment Station, School of Forest Resources and Conservation, University of Florida, Gainesville 32611. Plant Dis. 70:661-666. Accepted for publication 25 November 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-661.

Fusiform rust incidence data were analyzed from 1,882 predominantly 5-yr-old slash and loblolly pine plantations established on 67,740 ha in eight management areas in Florida and Georgia between 1961 and 1980. In both species, rust incidence increased from east to west within the region. In the northern portion of its range (central Georgia), rust incidence was greater on slash than on loblolly pine, but in the southern portion of its range (northeastern Florida), rust incidence was greater on loblolly than on slash pine. Temporal trends indicate that specific areas are perennially either high or low in rust incidence, although there are periods of increasing and decreasing epidemics. Rust management strategies can be designed for specific areas according to anticipated high or low rust incidence. Rust incidence was significantly lower (P = 0.01) among plantations established with seedlings from rust-resistant seed sources than among those established from largely unimproved, susceptible sources.

Keyword(s): Cronartium quercuum f. sp. fusiforme, disease management, disease resistance, epidemiology, Pinus elliottii var. elliottii, P. taeda.