Field performance of progenies of Pinus radiata selected for resistance to Diplodia-associated shoot dieback

Background: A severe outbreak of Diplodia-associated dieback Pinus radiata D.Don shoots in 1967 prompted a pilot programme selection for resistance to dieback. Plus trees were selected 1970 absence dieback, growth and tree form, seed collected. Methods: Twenty open-pollinated progenies plus two control lots field-tested on sites, assessed around 6.5 years after planting. Alternative measures shoot recorded, as dbhob scores form variables. Data analysed seedlot differences, heritability estimates various genetic correlations. Results: Dieback at one site allowed good resolution progeny whatever the measure. Remarkably, no response field was evident, unlike glasshouse inoculation trial. Nor did rankings correlate with those Between trial sites clear rank changes evident any trait. Conclusions: The disparity results from is unexplained, although role endophyte status postulated. Together non-recurrence past outbreaks, means that not promising.