Comparative Seedling Resistance of Pinus elliottii var. elliottii and P. elliottii var. densa to Cronartium quercuum f. sp. fusiforme. Roger S. Webb, Assistant Professor and Extension Forest Pathologist, School of Forest Resources and Conservation, University of Florida, Gainesville 32611. Robert L. Anderson, Supervisory Plant Pathologist and Resistance Screening Center Manager, USDA Forest Service Southeastern Area, State and Private Forestry, Asheville, NC 28803, and Kenneth M. Portier, Assistant Professor, Department of Statistics, University of Florida, Gainesville 32611. Plant Dis. 68:145-148. Accepted for publication 18 August 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-145.

Basidiospores of Cronartium quercuum f. sp. fusiforme were used to inoculate 1-mo-old seedlings from 21 families of Pinus elliottii var. elliottii, resistant and susceptible to fusiform rust, including several families of undetermined (unimproved) resistance, and seven unimproved bulk seed lots of P. elliottii var. densa. After 6 mo, seedlings from bulk seed lots of unimproved P. elliottii var. densa generally were more resistant to fusiform rust than the resistant, susceptible, or unimproved selections of P. elliottii var. elliottii. These results may partially explain the absence of fusiform rust in central and south Florida.

Keyword(s): slash pine, south Florida slash pine.