Susceptibility of Eight Pine Species to Comandra Blister Rust in Tennessee

Abstract

KAUFFMAN, B. W., H. W. APPLEGATE, C. E. CORDELL, and E. THOR. 1980. Susceptibility of eight pine species to comandra blister rust in Tennessee. Plant Disease 64:375-377. 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. In the South, comandra blister rust (Cronartium comandrae Pk.) has been found in Alabama, Arkansas, Kentucky, Mississippi, Missouri, and Tennessee (3,6,9,15,16). Previously, the disease was reported primarily on ponderosa pine (Pinusponderosa) and lodgepole pine (P. contorta) in the West and on jack pine (P. banksiana) in the north central states (3). The fungus also infects Jeffrey pine (P. jeffrey), knobcone pine (P. attenuata), pitch pine (P. rigida), red pine (P. resinosa), Scotch pine (P. sylvestris), Swiss mountain pine (P. mugo), and Table Mountain pine (P. pungens) (3,12). Susceptibility of red pine is questioned (10). Artificial inoculation of Austrian pine (P. nigra) with C. comandrae has been successful in nursery and greenhouse studies in Minnesota (2). Some species of southern pines are hosts for this obligate fungus parasite. Among them, loblolly pine (P. taeda) and shortleaf pine (P. echinata) are the most commonly affected (3,8). In addition, the rust occurs on naturally infected Virginia pine (P. virginiana), pond pine (P. serotina), spruce pine (P. glabra), and slash pine (P. elliotti) in Tennessee