Canadian Forest Service Publications

Resistance and tolerance of Douglas-fir seedlings to artificial inoculation with the fungus Ophiostoma pseudotsugae. 2018. Cruickshank, M. G., Bleiker, K. P., Sturrock, R. N., Becker, E., Leal, I. Forest Pathology. 48:e124 37.

Year: 2018

Issued by: Pacific Forestry Centre

Catalog ID: 40383

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1111/efp.12437

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We tested the resistance and tolerance of 79 Douglas-fir halfsibling seedling families to artificial inoculation with Ophiostoma pseudotsugae in a shade house experiment. The Douglas-fir beetle vectors the fungus where it colonizes the phloem and sapwood, often leading to tree mortality. The 79 halfsibling seedling families originated from four seed planning zones in BC that span ecological gradients ranging from moist-warm to cool-wet. We tested resistance to the fungus by measuring lesion size and tolerance by measuring seedling height. We found variation in both resistance and tolerance within seed zones and halfsibling hierarchies. Trees from zones and families that were shortest before inoculation appeared to have the most tolerance after inoculation suggesting a cost for carrying tolerance traits. There was a cost in height growth for resistance after inoculation versus wounding alone. There was no trade-off between family resistance and tolerance defence strategies indicating that both developed independently in the population. Higher resistance and lower tolerance to the fungus were the least commonly occurring trait combination in families. Douglas-fir trees are moderately shade intolerant at the sapling stage, and as height increment is crucial for light capture, they probably avoid costly strategies such as resistance alone. This defence strategy may change in older stands.