Correspondence of loblolly pine response for fusiform rust disease from local and wide-ranging tests in the Southern United States

Abstract

Fusiform rust is the most economically important disease of loblolly pine (Pinus taeda L.) in the southern United States. Estimates of family resistance to rust are critical for deployment decisions because 95% of loblolly pine plantations are established with individual families. If families show significant interactions with different pathogen inocula, then the performance of some families in different regions may not be predictable. This study compared rust breeding values of 56 loblolly families estimated from two independent sets of trials. We regressed the rust incidence breeding values of the families estimated from broadly based field tests on breeding values of the same families estimated from narrowly based tests. The model F test was highly significant (P < 0.0001), and breeding values based on local testing explained 75% of the variation in breeding values based on wide-range geographic testing, indicating that local rust breeding values are relatively reliable predictors of families’ performance across a broad range of sites. Family rankings were highly consistent across test sites within broadly and narrowly based testing schemes as shown by type B genetic correlations (0.90 and 0.91). We conclude that field testing provides a reliable prediction of the operational value of loblolly families for deployment in regions with a high hazard for fusiform rust.