Plant Disease (2017) 101, 470-479

Renate Heinzelmann, Simone Prospero and Daniel Rigling (2017)
Virulence and stump colonization ability of Armillaria borealis on Norway spruce seedlings in comparison to sympatric Armillaria species
Plant Disease 101 (3), 470-479
Abstract: Although Armillaria borealis is one of the closest relatives of the aggressive root rot pathogen A. ostoyae, little is known about its ecology. In central and northern Europe, A. borealis often co-occurs with A. ostoyae or A. cepistipes, a weak pathogen, in conifer or mixed-forest stands. In this study, the virulence of 10 A. borealis, nine A. ostoyae, and five A. cepistipes isolates toward 2- and 4-year-old potted Norway spruce (Picea abies) seedlings was assessed. In addition, the ability of all isolates to colonize fresh stumps cut from 6-year-old Norway spruce seedlings was tested. All inoculations were done by insertion of Armillaria-colonized hazelnut stem segments into the soil substrate. On the 2-year-old seedlings, A. borealis and A. ostoyae showed, overall, a similar virulence 29 months after inoculation whereas, on the 4-year-old seedlings, A. ostoyae was more virulent. The third species in the experiment, A. cepistipes, caused almost no seedling mortality. Six months after cutting, the highest percentage of stumps was colonized by A. ostoyae (94.3%), followed by A. borealis (85.2%), and A. cepistipes (78.4%). Our inoculation experiments show that A. borealis has a clear pathogenic potential toward Norway spruce seedlings. However, compared with A. ostoyae, damage caused by A. borealis may decrease more rapidly with increasing tree age. Similar to other Armillaria species, A. borealis seems to be an efficient colonizer of fresh stumps.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Daniel Rigling

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Armillaria borealis	Spruce (Picea)