Fusiform Rust in Crosses Among Resistant and Susceptible Loblolly and Slash Pines
Abstract Progenies from a half-diallel cross among six loblolly pines (Pinus taeda L.) and another among six slash pines (P. elliottii Engelm. var. elliottii) were field-tested in central Georgia for fusiform-rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) resistance. Threeof each set of six parents were rated resistant (R) and three susceptible (S) to the fungus relative to check lots in previous progeny tests. For both species, relative susceptibility of the three types of progenies at age 5 years was R x R < R x S < S x S. The R x R and R x S progeniesin slash pine had considerably less infection than did the same types of progenies in loblolly pines. All S x S progenies were heavily infected. Heritability estimates for percentage infection and average galls per tree indicated that in these progenies, family selection should be based onpercentage infection for slash pine and galls per tree for loblolly pine. South. J. Appl. For. 13(4):174-177.