Fusiform Rust in Half-Diallel Cross Progenies of Resistant or Susceptible Loblolly and Slash Pines

Progenies from a half-diallel cross among six loblolly pines and another among six slash pines were field-tested in central Georgia for fusiform-rust resistance. Three of each set of six parents had been typed as resistant (R) and three as susceptible (S) to the fungus in previous progeny tests that included check lots. At age 5 years, the 15 progenies of each species varied significantly in percentage infection and number of galls per tree. The RXR slash crosses produced highly resistant offspring but the RXR loblolly crosses produced progenies that were 79 percent infected. All SXS crosses of both species produced very susceptible progenies and RXS progenies were intermediate in susceptibility. Each set of parents varied significantly in general and specific combining abilities. The mean breeding values for the R slash parents were 25.5 for percent infection and 0.57 for galls per tree. For loblolly R parents, the corresponding values were 79.4 and 3.05. For the S parents, the respective breeding values were 94.1 and 3.26 for slash and 96.1 and 6.43 for loblolly. Keywords: Pinus taeda, Pinus elliottii, Cronartium quercuum f. sp. fusiforme.

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Author(s): Earl R. Sluder

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1989

Section: Concurrent Session 3B