Susceptibility of Shortleaf Pine Seedlings to Infection by Cronartium quercuum f. sp. fusiforme. John F. Kraus, Plant Geneticist, Southeastern Forest Experiment Station, Dry Branch, GA 31020. H. R. Powers, Jr., Plant Pathologist, Southeastern Forest Experiment Station, Athens, GA 30602. Plant Dis. 68:324-325. Accepted for publication 23 October 1983. 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, 1984. DOI: 10.1094/PD-68-324.

Seedlings from 14 open-pollinated seed lots of Pinus echinata (shortleaf pine) and two open-pollinated seed lots of P. taeda (loblolly pine) were artificially inoculated with basidiospores derived from two sources: rust galls on shortleaf × loblolly pine hybrids and galls on loblolly pine. The objective was to determine if basidiospores from the hybrid inoculum sources would be more virulent than those from loblolly pine on the shortleaf seedlings. All seed lots of shortleaf pine were highly resistant (97–100% disease-free), whereas both loblolly pine seed lots were much less resistant (47–62% disease-free) to inoculum from both sources.