Relationship of Growth Reduction in Douglas-fir to Infection by Armillaria Root Disease in Southeastern British Columbia

1989 ◽  
Vol 79 (4) ◽  
pp. 482 ◽  
Author(s):  
W. J. Bloomberg
2015 ◽  
Vol 45 (12) ◽  
pp. 1803-1805 ◽  
Author(s):  
Bill Chapman ◽  
Bruce Schellenberg

Ringbarking is a girdling technique that is used prior to timber harvesting to reduce losses to Armillaria root disease in some parts of the world. The technique had not previously been evaluated in British Columbia, Canada. Small plots of primarily Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees that were ringbarked prior to timber harvesting had approximately 50% lower levels of Armillaria root disease caused tree mortality in young trees after 15 years than plots of trees that were not ringbarked. Ringbarking did not reduce Armillaria root disease in this trial as much as has been reported in other research. This could be attributable to the centre of the small plots being within 5–10 m of live and dead Armillaria-infected trees in the surrounding forest. The treatment did reduce the severity of the disease by both statistically and biologically significant amounts and, therefore, warrants further investigation as a possible treatment where timber harvesting is conducted in Armillaria root disease affected stands.


2011 ◽  
Vol 41 (8) ◽  
pp. 1598-1605 ◽  
Author(s):  
William K. Chapman ◽  
Bruce Schellenberg ◽  
Teresa A. Newsome

This trial, conducted near Nakusp, British Columbia, compares pushover logging (combination tree felling and root removal technique using large machines to push trees out of the ground) with handfalling logging (no root removal) for effects on the incidence of armillaria root disease in postharvest regeneration. Pushover logging did not reduce levels of root disease, expressed as percentage tree mortality, over handfalling harvesting on this site. High variability of measured disease levels within some treatments and few replicates lowered the power of the trial. However, in addition to being statistically insignificant, the mean differences between the two main treatments were small and biologically uninteresting, and the response was inconsistent in direction. The trial also included three mature timber retention levels as treatments, and there seemed to be a trend of declining root disease with increased retention of stems. This phenomenon should be further investigated as current literature is not clear on the response of armillaria to partial harvesting. There was a strong suggestion of a difference between susceptibility of natural and planted seedlings to armillaria root disease, with natural regeneration being less susceptible. Thuja plicata Donn ex D. Don was less affected by armillaria root disease than other species in this trial, whether it was planted or naturally regenerated.


Botany ◽  
2012 ◽  
Vol 90 (8) ◽  
pp. 711-721 ◽  
Author(s):  
M.G. Cruickshank ◽  
C.N. Filipescu

We used allometric relationships to quantify Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) stem and crown adaptation to Armillaria root disease (caused by Armillaria ostoyae (Romagn.) Herink). At four sites, we measured height, diameter, height to live crown, crown width and length, sapwood area at base of live crown, and infection duration for healthy and infected Douglas-fir trees. Diseased trees were on average smaller than healthy trees for all measured variables, but there were also proportional changes between tree parts suggesting allocation shifts to disease. Infected trees were shorter in relation to stem diameter compared with healthy trees by 4% on average. Crown diameter was positively related to stem diameter (0.24 m·cm–1) but not to disease or competition. Diseased tree crown lengths were on average 0.5 m shorter for a given crown diameter than healthy trees—akin to response to light competition except this also occurred in the upper canopy. Prolonged infection reduced crown length probably through shedding of lower branches and by reducing stem apical growth, possibly related to changed hydraulic architecture or light requirements. Crown surface area was related to stem sapwood area (0.81 m2·cm–2) but unaffected by disease or competition. We discuss how shifting allocation could reveal important implications for life strategies involving whole tree adaptations to disease and tree to tree interactions, and for wood quality and forest inventory.


2010 ◽  
Vol 86 (2) ◽  
pp. 263-266 ◽  
Author(s):  
M G Cruickshank

For a few tree species, scattered accounts of impact caused by root disease exist in the literature mainly at the tree level. No product quality impacts have ever been measured or properly costed. To provide some information on value impacts, green rough-sawn Douglas-fir lumber was cut from trees with and without Armillaria root disease. This produced 80 boards from six trees in two planted stands. Fewer boards came from living diseased trees compared to healthy trees of similar diameter (1.3 m) at both sites, suggesting that disease may affect stem taper or form. Lumber from diseased trees was affected most often by warp and for healthy trees by knots, but warp affected value the most. Disease appears to have at best no effect, and at worst, a negative effect on lumber value but is not likely to increase value. This is the first report of the impact of a root disease on lumber quality and value, but further work would be required to properly assess this. Key words: disease, Armillaria root disease, conifer, Douglas-fir, wood quality, lumber warping, lumber value, lumber grading


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