Forest Genetics Topics:
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Virulence in C. ribicola
| Sugar pines with MGR that resisted early waves of infection for 14 years in a test plantation suddenly developed multiple infections from a new and virulent race of blister rust. Happy Camp, Siskyou Mountains California |
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| Mixed resistant (HR) and susceptible (yellow) needle spot phenotypes on sugar pine with MGR. (Spots are counted before they coalesce). Inoculum is from Thompson Ridge (TR). |
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| Frequency of vcr1 is determined by the proportion of total spots that are yellow. |
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| MGR in western whie pine is also neutralized by a virulent race. However, this race has no affect on MGR in sugar pine, and the race neutralizing MGR in sugar pine has no affect on MGR in western white pine. This is typical of gene-for-gene systems. |
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