Fusiform Rust Infection of Loblolly Pines that Survived Resistance Screening and of Their Progeny. R. C. Schmidtling, Principal Plant Geneticist, Southern Forest Experiment Station, USDA Forest Service, Gulfport, MS 39505. C. H. Walkinshaw, Principal Plant Pathologist, Southern Forest Experiment Station, USDA Forest Service, Gulfport, MS 39505. Plant Dis. 69:491-493. Accepted for publication 23 December 1984. 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, 1985. DOI: 10.1094/PD-69-491.

Rustfree loblolly pine seedlings previously inoculated with Cronartium quercuum f. sp. fusiforme in a tent-style inoculation chamber were used to establish two plantings. After 10 yr, incidence of infection in the first planting was 22% compared with 29% in previously uninoculated checks. In the other planting, incidence of infection was positively correlated with rust incidence in the same families after the original tent inoculations. In both plantings, rustfree survivors of families with low rust incidence in the inoculation test generally remained rustfree after planting in the field; in contrast, many gallfree survivors of susceptible families became infected in the field. For a second-generation test, seedling progeny of eight open-pollinated rustfree survivors in the two field plantings were artificially inoculated. The only highly resistant second-generation family was derived from a family that was resistant in the original inoculation. The remainder were susceptible.