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Richard A. Sniezko, Andrew Bower, and Jude Danielson

Seedlings from 12 sugar pine (Pinus lambertiana Dougl.) and 13 western white pine (Pinus monticola Dougl.) families were planted at Happy Camp, Calif., in 1996. Assessment in Summer 1999 indicated moderate levels of white pine blister rust (Cronartium ribicola Fischer) infection. This paper focused on the species differences and showed that sugar pine had a higher incidence of stem infection (active and inactive cankers) and more stem infections per tree than western white pine. An unexpected result was the very high percentage of infections that were bark reactions (completely inactivated infections), despite the fact that only some of the families of both species were selected for this mechanism. Assessments in subsequent years will track the future performance of the two species and of the individual families.

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John A. Muir and Richard S. Hunt

Introductions of white pine blister rust (WPBR, causal fungus: Cronartium ribicola J.C. Fischer) to eastern and western North America before 1915 caused such extensive damage that western white pine (Pinus monticola D. Don) was essentially abandoned as a manageable forest tree species for over 60 years. Recent results from WPBR resistance selection and breeding programs, and from field trials of tree spacing, pruning and bark excision treatments have supported efforts to increase establishment and to intensively manage western white pine. Western white pine is a desirable component in many forested areas because of its faster growth and much higher value compared to many other associated tree species. It also has a low susceptibility to armillaria root disease caused by Armillaria ostoyae (Romagnesi) Herink and laminated root rot, caused by Phellinus weirii (Murr.) Gilb. Some regulations, e.g., Forest Practices Code of British Columbia (BC) Act, require anyone who harvests timber on provincial forestland and uses western white pine for reforestation to either plant genetically resistant western white pine stock or prune susceptible young trees for protection. Risks of increased WPBR associated with increased commercial cultivation of gooseberries and currants (Ribes L.) have yet to be determined. However, major threats appear to include 1) increase in local amounts of spores for nearby infection of pines; and 2) possible introductions or development of new, virulent races of C. ribicola, particularly from eastern to Pacific northwestern North America. In view of these possible threats, we recommend that existing regulations and legislation should be amended, or possibly new measures enacted, to permit propagation and commercial cultivation only of varieties of Ribes that are immune or highly resistant to WPBR.

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R.S. Hunt and G.D. Jensen

For the white pine blister rust disease (WPBR), reports conflict concerning the time of year the pathogen, Cronartium ribicola J.C. Fisch., infects western white pine (Pinus monticola D. Don) and what needle age increments are most susceptible. To determine timing of infection, western white pine seedling were placed under infected currants (Ribes nigrum L.) for 1-week periods from May to November. Needles became spotted and stems cankered after exposure to diseased currants from early summer until leaf drop in November. To determine what foliage age increment was most susceptible, 5-year-old seedlings were placed in a disease garden, and older trees were inoculated in situ. All age increments of pine foliage were susceptible to infection. For young seedlings, all age increments were about equally susceptible, but on some older seedlings and trees, the current year's foliage appeared more resistant than older foliage.

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Myounghai Kwak, Jeong-Ki Hong, Eun Sil Lee, Byoung Yoon Lee, Min Hwan Suh, and Bert Cregg

genetic variation has also been applied to determine whether breeding for white pine blister rust ( Cronartium ribicola ) has affected diversity in western white pine ( Pinus monticola ) ( Kim et al., 2003 ). A previous microsatellite analysis of wild A

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Kelly J. Vining, Q Zhang, C.A. Smith, and T.M. Davis

had stop codons or frameshifts. In pine ( Pinus monticola Dougl. ex. D. Don), Liu and Ekramoddoullah (2003) found that 18 of 46 genomic RGA clones and 14 of 21 cDNA RGA clones had at least one stop codon or frameshift. RGAs with interrupted ORFs may

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Xiuli Shen and Myeong-Je Cho

Committee, 30 Mar.–1 Apr. 1992, Univ. California, Davis Feurtado, J.A. Ambrose, S.J. Cutler, A.J. Ross, A.R.S. Abrams, S.R. 2004 Dormancy termination of western white pine ( Pinus monticola Dougl. Ex D. Don) seeds is associated with changes in abscisic acid