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Resistance

Comparison of Six Geographic Sources of Loblolly Pine for Fusiform Rust Resistance. H. R. Powers, Jr., Chief plant pathologist, USDA Forest Service, Southeastern Forest Experiment Station, Forestry Sciences Laboratory, Carlton Street, Athens, GA 30602; F. R. Matthews, principal plant pathologist, USDA Forest Service, Southeastern Forest Experiment Station, Forestry Sciences Laboratory, Carlton Street, Athens, GA 30602. Phytopathology 70:1141-1143. Accepted for publication 8 May 1980. 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, 1980. DOI: 10.1094/Phyto-70-1141.

Loblolly pine seedlings grown from seed collected in six geographic areas across the natural range of this species were inoculated with rust fungi collected from each seed source area. There were significant differences in disease susceptibility among seed sources; the Maryland source was the most resistant. The interactions between specific seed sources and rust fungus collections were highly significant, which indicated that seed from several of the sources can be used to reduce the impact of fusiform rust. Seedlings from all seed source areas were most susceptible to infection by their respective local rust fungus isolates.