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Operational program to develop Phytophthora lateralis-resistant populations of Port-Orford-cedar (Chamaecyparis lawsoniana)Author(s): R.A. Sniezko; J. Hamlin; E.M. Hansen
Source: In: Sniezko, Richard A.; Yanchuk, Alvin D.; Kliejunas, John T.; Palmieri, Katharine M.; Alexander, Janice M.; Frankel, Susan J., tech. coords. 2012. Proceedings of the fourth international workshop on the genetics of host-parasite interactions in forestry: Disease and insect resistance in forest trees. Gen. Tech. Rep. PSW-GTR-240. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. pp. 65-79
Publication Series: General Technical Report (GTR)
Station: Pacific Southwest Research Station
PDF: View PDF (3.74 MB)
DescriptionPort-Orford-cedar (Chamaecyparis lawsoniana (A. Murr.) Parl.) (POC) is a long-lived conifer native to northwestern California and southwestern Oregon. It has been widely used in horticulture in both western North America and elsewhere. The accidental introduction of the non-native pathogen Phytophthora lateralis into North America and Europe has raised concerns about the future viability of POC in some forest ecosystems, in managed forests, and in horticultural settings. Fortunately, some level of natural genetic resistance to P. lateralis exists in POC. Utilizing this genetic resistance in reforestation and restoration of POC offers considerable benefits without the negative side-effects of alternatives. In 1997, the USDA Forest Service and USDI Bureau of Land Management began a large operational program to develop populations of POC with genetic resistance to P. lateralis. With essential ongoing pathology support from Oregon State University, this resistance program has advanced rapidly. The program goal includes developing orchards for production of resistant seed, while maintaining genetic variation and adaptability within the species. Using classical selection and testing techniques, over 12,600 initial field selections have been made, resistance screening protocols refined, 13 breeding zones delineated, field trials established, eight seed orchards started, and resistant seed produced and being used for some breeding zones. Early, short-term testing in the greenhouse of orchard seedlots shows a 30 percent or higher survival than woods-run seedlots. In greenhouse testing, survival among individual susceptible and resistant families varies from 0 to 100 percent, and at least two types of resistance are apparent. Field trials have been established and early results are encouraging, but much longer monitoring is needed to examine a full range of sites for efficacy and durability of resistance under different environments and a changing climate. The recent finding of P. lateralis in Europe and Taiwan warrants further investigation into the pathogenicity of these isolates on resistant POC. The biology of POC and the concerted efforts of all those involved have made this fast moving resistance program one of the few involving non-native pathogens to produce seed for restoration and reforestation. Planting the less susceptible seedlings will increase the frequency of resistance in areas affected by P. lateralis and help to establish a new balance in affected ecosystems.
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CitationSniezko, R.A.; Hamlin, J.; Hansen, E.M. 2012. Operational program to develop Phytophthora lateralis-resistant populations of Port-Orford-cedar (Chamaecyparis lawsoniana). In: Sniezko, Richard A.; Yanchuk, Alvin D.; Kliejunas, John T.; Palmieri, Katharine M.; Alexander, Janice M.; Frankel, Susan J., tech. coords. 2012. Proceedings of the fourth international workshop on the genetics of host-parasite interactions in forestry: Disease and insect resistance in forest trees. Gen. Tech. Rep. PSW-GTR-240. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. pp. 65-79.
KeywordsPort-Orford-cedar, Chamaecyparis lawsoniana, Phytophthora lateralis, resistance program
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