Resistance of loblolly pine sources to fusiform rust in field progeny tests
Powers, H.R.J.; Kuhlman, E.G.
Research Paper Southeastern Forest Experiment Station, USDA Forest Service (SE-268): 10
Three field progeny tests in Greene County, Georgia, USA, of 28 loblolly pine (Pinus taeda) seed sources with possible resistance to fusiform rust (Cronartium quercuum f. sp. fusiforme [C. fusiforme]) indicated that all sources had moderate to high resistance after 10 to 14 years in the field. Susceptible check sources had 86 and 78% rust infection after 13 and 14 years respectively, while the various seed sources had infection percentages ranging from 1 to 57. In one test, field infection of rust-free seedlings surviving the concentrated basidiospore spray (CBS) inoculation system had a correlation coefficient of r=0.85 with the original CBS infection results. Generally, the CBS system correctly classified resistant and susceptible sources; however, seven sources with field resistance were classed as susceptible in the CBS system. Therefore, field progeny tests will continue to play an important role in evaluating rust-resistant pine sources.