Climate-Host Mapping of Phytophthora ramorum, causal agent of sudden oak death

Abstract

We modeled Phytophthora ramorum infection using the North Carolina State University- Animal and Plant Health Inspection Service Plant Pest Forecasting System (NAPPFAST) for the conterminous United States. Our infection model is based on a temperature-moisture response function. The model parameters were: leaf wetness, minimum temperature, optimum temperature and maximum temperature over a specified number of accumulated days. The NAPPFAST weather database, which involves approximately 2,000 weather stations across North America, was used to generate a spatially interpolated climate match for P. ramorum infection at a 10 km² resolution. The model was used to create maps showing the frequency of favorable years for infection, which were validated by comparison with historical P. ramorum observations from California in urban and natural settings. We then overlaid climate match areas for P. ramorum infection with hardwood forest density and understory host density to generate a composite risk map. We further increased the precision of the maps by applying masks that removed areas where: 1) no climate match occurred, 2) lethal cold soil temperatures for P. ramorum occurred, 3) no hardwood hosts occurred and 4) no understory hosts occurred. These maps are designed to improve the efficacy and economy of survey and detection activities for P. ramorum by federal, state and local regulatory agencies. We also generated global maps using the NAPPFAST system at a 55 km2 monthly resolution. Parameters used in the global model were: minimum average monthly temperature, maximum average monthly temperature and monthly precipitation. We used an air temperature lethal cold mask as a surrogate for soil temperature in the global model. These maps may assist in the search for the origin of P. ramorum.

Parent Publication

• Proceedings of the sudden oak death third science symposium

Citation

Magarey, Roger; Fowler, Glenn; Colunga, Manuel; Smith, Bill; Meentemeyer,Ross. 2008. Climate-Host Mapping of Phytophthora ramorum, causal agent of sudden oak death. In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M., tech. coords. 2008. Proceedings of the sudden oak death third science symposium. Gen. Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. pp. 269-275