Susceptibility of Eight Pine Species to Comandra Blister Rust in Tennessee. B. W. Kauffman, Forest Insect and Disease Specialist, Tennessee Division of Forestry, Nashville 37220. H. W. Applegate, Assistant State Forester, Tennessee Division of Forestry, Nashville 37220; C. E. Cordell, Nursery Disease Specialist, Forest Pest Management, SEA, S & PF, USDA Forest Service, Asheville, NC 28803; and E. Thor, Professor of Forestry, University of Tennessee, Knoxville 37901. Plant Dis. 64:375-377. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-375.

Field studies in Tennessee compared the relative susceptibilities of eight pine species to natural infection by comandra blister rust (Cronartium comandrae) over an 8-yr period after planting. Pond, shortleaf, and slash pines were most susceptible. Loblolly and Virginia pines were less susceptible, and eastern white pine, red pine, and Japanese black pine were resistant. Differences in location of comandra rust needle infection were observed among pond, shortleaf, and slash pines. An apparent minimum 2-yr period was needed for developing rust stem cankers to cause tree mortality after natural direct stem infections through attached needles. All rust stem cankers detected during the first 5 yr after planting caused mortality the subsequent year on all susceptible species. Proximity of the alternate host, false toadflax, to infected pines was an apparent requirement, but false toadflax abundance was not correlated with subsequent incidence of rust-caused stem infection and mortality. Loblolly and shortleaf pine plantings should be avoided on sites where false toadflax would be close to the majority of planted pine seedlings.