Genetic improvement of resistance to cyclaneusma needle cast in Pinus radiata

Progeny testing of resistance to needle loss caused by Cyclaneusma minus has been included in the needle disease resistance strategy of Pinus radiata in New Zealand since the late 1970s. Data on progeny trials, two in the North Island of New Zealand and one in Tasmania, Australia were available to estimate heritability, between trait genetic correlations and genotype by environment interaction. Resistance to cyclaneusma needle cast had moderate estimates of heritability (0.25 to 0.46) at all sites. Genetic correlations between the assessed traits indicated that selection for faster early growth, i.e. tree height at age four and diameter at breast height at age six favours trees that are prone to Cyclaneusma infection, whilst a favourable genetic association between resistance to cyclaneusma needle cast and productivity was evident at later assessment that was at age nine. No significant genotype by environment interaction was found for resistance to cyclaneusma needle cast, however, stability of genotypes across a wider range of environments and with a high genetic connectedness require more research. Considerable genetic improvement can be achieved for resistance to cyclaneusma needle cast and indirect selection for the trait should be pursued by selecting for productivity and culling susceptible genotypes from breeding.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author