Risks affecting breeding objectives for radiata pine in Australia

This paper examines the effects of climatic and biotic risks -drought, Essigella aphid, Dothistroma needle blight and Fusarium pitch canker-on the Pinus radiata production system in Australia. These risks were examined in relation to climatic variables in order to develop 'hazard ratings' for planting sites. Bio-economic models were developed to link the risks with the established breeding objective for solid wood production. Economic weights were derived for resistance traits that can be used in index selection for breeding and deployment. Under one scenario, drought-affected sites can achieve an internal rate of return of > 7.0% only if the land rental is sufficiently low, that is < $25 ha(-1) y(-1), but replanting costs and volume losses due to mortality can be significant. An average of 13.5% defoliation caused by Essigella aphid would reduce volume growth over a rotation period by about 10%. A modest increase in profitability can be achieved through deployment of Essigella-resistant genotypes. Reduction of volume growth by Dothistroma defoliation at an early age (4-10 y) had a relatively small effect on subsequent yield reduction. At a site with a high level of infection, however, the profitability of improving Dothistroma resistance was similar to that for improving growth on uninfected sites. The economic importance of risk traits relative to MAI over the entire radiata pine plantation estate was generally low: 4% for pine aphid, 0.6% for needle blight and 1.3% for pitch canker resistance. Essigella pine aphid is the most important pest currently affecting the productivity of radiata pine plantations in Australia.