Canadian Forest Service Publications
Necrophylactic periderm formation in the roots of western larch and Douglas-fir trees infected with Armillaria ostoyae. II. The response to the pathogen. 2004. Robinson, R.M.; Morrison, D.J.; Jensen, G.D. Forest Pathology 34: 119-129.
Issued by: Pacific Forestry Centre
Catalog ID: 25003
Availability: Order paper copy (free)
Periderm formation was studied in bark samples collected from the roots of western larch and Douglas-fir trees infected with Armillaria ostoyae. Necrophylactic periderms formed in advance of infection and successfully restricted continued fungal spread in 68% and 45% of the samples collected from 10- and 27-year-old western larch respectively. However, all periderms formed in 11- and 25-year-old Douglas-fir had been breached by the advancing fungus. In both species, necrophylactic periderms were commonly breached at the junction of the periderm with the vascular cambium. In western larch, stone phellem often comprised the external phellem layer of necrophylactic periderms with multiple bands of phellem. In 27-year-old western larch, infection was often confined to discreet lesions bounded by multiple periderms with multiple bands of phellem. In both tree species, phellem production was greater in response to infection than in response to wounding.