Genotype-Environment Interaction in Rust Resistance in Mississippi Loblolly Pine

Seed was collected from five trees in each of 115 sources of loblolly ( Pinus taeda L.) pine in or near Mississippi and grown in three widely separated planting locations for 10 years. The loblolly population west of the Mississippi River, in the loess hills along the east side of the flood plain of the Mississippi River, and in the western Florida Parishes of Louisiana proved to be consistently more resistant to fusiform rust ( Cronartium quercuum [Beck.] Miyabe ex Shirai f. sp. fusiforme ) than loblolly pine from the rest of the study area. This resistance was stable in all three plantings. Less stable was the occasional resistance found in individual half-sib families scattered throughout the generally susceptible population. About 2.5 percent of the families from the generally susceptible population were resistant in all three planting locations. Forest Sci. 28:797-809.