Title: White pine blister rust resistance of 12 western white pine families at three field sites in the Pacific Northwest
Author: Sniezko, Richard A.; Danchok, Robert; Hamlin, Jim; Kegley, Angelia; Long, Sally; Mayo, James;
Source: In: Sniezko, Richard A.; Yanchuk, Alvin D.; Kliejunas, John T.; Palmieri, Katharine M.; Alexander, Janice M.; Frankel, Susan J., tech. coords. 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. 356-367
Publication Series: General Technical Report (GTR)
Description: Western white pine (Pinus monticola Douglas ex D. Don) is highly susceptible to the non-native, invasive pathogen Cronartium ribicola, the causative agent of white pine blister rust. The susceptibility of western white pine to blister rust has limited its use in restoration and reforestation throughout much of western North America. Fortunately, some genetic resistance to blister rust exists in western white pine, and several operational programs to select for resistance and develop orchards to produce resistant seed exist. These programs, such as that of the U.S. Department of Agriculture, Forest Service (USDA FS) Pacific Northwest Region, utilize short-term artificial inoculation trials of seedlings to evaluate resistance. However, until recently, there have been very few multi-site field trials to examine resistance closely. In this paper, we report on 12 western white pine families common to three field trials in western Oregon and northern California. The sites have been assessed for white pine blister rust infection and mortality at multiple ages since they were planted from 1996 to 2003. The 12 families had been selected based on results in previous artificial inoculation trials of seedlings of more than 4,000 parent trees at Dorena Genetic Resource Center (DGRC). Most of the families were from wind-pollinated seedlots from forest stands and represent some of the top ranked families from a first round of selection. Timing and frequency of field trial assessments varied to coincide with the appearance and development of rust infection at the three sites. By 2010, all three sites had moderate to high levels of blister rust infection, and moderate levels of mortality were present at some sites. The susceptible control family had 92 to 100 percent of trees with stem symptoms at the three sites, while only 29 to 43 percent of the trees in the top resistant family showed stem symptoms in those trials. The high level of stem symptoms in the two families with the Cr2 gene, which conditions a hypersensitive-like reaction (HR) in the needles, suggests that it is likely that a virulent vcr2 strain of rust is present at all three sites. A wide range in family variation is present at all three sites for the proportion of trees with stem symptoms. Mortality lags behind stem infection, and more time is needed to assess the full impact of current stem infections. Infected trees in families with putative partial resistance traits such as bark reaction noted in previous screening trials will continue to be followed to examine their subsequent survival under field conditions. In general, moderate to high correlations were found between current levels of resistance at the three sites and seedling screening results from DGRC, providing some of the first field validation of results of short-term testing. These current results and future assessments will provide valuable information on the level of rust resistance and survival that land managers can expect over a range of sites. Long-term monitoring of these sites will be essential to evaluate durability of the various resistance types. Ongoing breeding efforts are aimed at increasing the levels of resistance to provide greater opportunities for successful reforestation and restoration use.
Keywords: Pinus monticola, Cronartium ribicola, rust resistance, field trials, operational program
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Sniezko, Richard A.; Danchok, Robert; Hamlin, Jim; Kegley, Angelia; Long, Sally; Mayo, James. 2012. White pine blister rust resistance of 12 western white pine families at three field sites in the Pacific Northwest. In: Sniezko, Richard A.; Yanchuk, Alvin D.; Kliejunas, John T.; Palmieri, Katharine M.; Alexander, Janice M.; Frankel, Susan J., tech. coords. 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. 356-367.
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