Spatial pattern of the density of <i>Armillaria</i> epiphytic rhizomorphs on tree collar in an oak stand

Marçais, Benoît; Caël, O.

doi:10.1111/j.1439-0329.2006.00431.x

Cited by 6 publications

(13 citation statements)

References 24 publications

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“…This common species is widespread in hardwood forests as epiphytic rhizomorphs present on tree collars (Guillaumin et al. , 1993; Marçais & Caël, 2006). It has been shown to induce significant lesions only on trees weakened by other factors (Wargo & Harrington, 1991; Sicoli et al.…”

Section: Discussionmentioning

confidence: 99%

Occurrence of Hymenoscyphus pseudoalbidus on infected ash logs

et al. 2012

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Ash decline induced by Hymenoscyphus pseudoalbidus is an emerging disease that severely affects Fraxinus excelsior stands in Europe. There has been an invasive spread of the disease from east to west in Europe over the last decade. Wood discoloration on infected trunks has been reported, but few data are available on the involvement of H. pseudoalbidus in such symptoms. Transport and trade of ash logs could introduce the pathogen into disease-free areas and therefore accelerate its dissemination. The aim of this study was to assess the prevalence and severity of H. pseudoalbidus in ash logs in infested areas located in the northeast of France and to clarify the role of secondary pathogens in ash decline. The results showed that prevalence of H. pseudoalbidus on collar lesions was high in the study area. The pathogen was able to produce conidia from infected wood. Thus, export of ash logs could represent a potential risk for spreading the disease. Involvement of Armillaria spp. in the decline process was confirmed, while no Phytophthora-induced collar lesions were found. Studying both disease prevalence and the age of callus tissues surrounding collar lesions in 60 ash stands enabled the origin of the disease in the study area to be determined.

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Section: Discussionmentioning

confidence: 99%

Occurrence of Hymenoscyphus pseudoalbidus on infected ash logs

et al. 2012

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“…However, profuse production of basidiomata in autumn, suggests high abundance of the species in Serbian oak forests. It is likely that A. mellea colonizes vigorous hosts without causing visible symptoms until other factors stress the tree (M arçais and C aël 2006). During host stress, other Armillaria species may attack tree, but A. mellea has a competitive advantage because it is already established in the substrate.…”

Section: Discussionmentioning

confidence: 99%

Ecology of Armillaria species in managed forests and plantations in Serbia

2009

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The distribution of Armillaria species was investigated in Serbian forest ecosystems, in relation to the main host species attacked, forest-types, geography and altitude. In total, 388 isolates were identified from 36 host species in 47 sites. Armillaria gallica was the most commonly observed species with the widest distribution and with an altitudinal range of 70-1450 m, it was the dominating Armillaria species in lowland alluvial forests and in Quercus and Fagus forests at higher elevations. Armillaria mellea occurred in Quercus spp. -dominated forests in the north and central regions at 70-1050 m. Sixty-eight per cent of the A. mellea isolates were collected from living hosts, most commonly in declining conifer plantations. Armillaria ostoyae was distributed in the cooler coniferous forest types and plantations in the Dinaric Alps in the south of Serbia, at 850-1820 m. Armillaria cepistipes was found in the eastern and southern hilly and mountainous regions of the country, at 600-1900 m. Most isolates were obtained from conifers and rhizomorphs in the soil around decaying stumps. Armillaria tabescens was found only on dead oak material in the northern and eastern regions of the country at altitudes lower than 600 m.

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“…The difference in frequency of branch colonization by A. gallica between the three treatments was analysed by logistic regression analysis, including a block effect. The density of epiphytic rhizomorphs on the tree collars was also checked at the end of the experimental period, in the summer of 2003 (Marçais & Caël 2006).…”

Section: Methodsmentioning

confidence: 99%

“…From colonized wood, it forms in forest soil a network of rhizomorphs, perennial cord‐like organs that are capable of colonizing the tree bases of most oak trees in the forest. Rhizomorphs develop epiphytically on the root collar (Redfern & Filip 1991; Marçais & Caël 2006). A. gallica is an opportunistic pathogen with a low level of aggressiveness and is unable to colonize vigorously growing hosts (Wargo & Harrington 1991).…”

Section: Introductionmentioning

confidence: 99%

“…This soil pathogen is very common and it is difficult to identify comparable trees colonized or not by epiphytic rhizomorphs. However, A. gallica inoculum potential can show very high within‐stand heterogeneity levels (Marçais & Caël 2006) and comparing the response to defoliation of trees subjected to high or low inoculum potential is possible. The hypothesis was that trees with a dense root collar colonization by epiphytic A. gallica rhizomorphs would exhibit a greater decline or mortality following stress (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Role of an opportunistic pathogen in the decline of stressed oak trees

Marçais

Bréda

2006

Journal of Ecology

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1 The importance of opportunistic pathogens, in particular Armillaria species, in forest decline has often been open to debate. 2 In order to assess the role of Armillaria gallica in the decline of oak trees, 60 Quercus robur trees with high (HIP trees) or low (LIP trees) levels of A. gallica inoculum, as measured by the density of epiphytic rhizomorphs on the root collar, were artificially defoliated for 2 years. Half of the HIP trees were treated when first defoliated with boric acid to reduce the A. gallica inoculum potential (BHIP trees). The ability of in situ rhizomorphs to colonize plant material was similar for LIP and BHIP, but was lower than in HIP trees, indicating that the boric acid treatment reduced the level of A. gallica inoculum. 3 Tree growth was similar between treatments as determined by dendrochronological comparisons. Although defoliation greatly reduced both tree growth and sapwood starch reserves at the beginning of autumn, growth response to defoliation and sapwood starch concentration at the beginning of autumn were similar for LIP, BHIP and HIP trees. 4 HIP trees suffered considerably greater crown deterioration and mortality following defoliation than either BHIP or LIP trees (62%, 32% and 5% mortality rates, respectively). The trees that died had very low sapwood starch concentrations. In addition, at similar levels of sapwood starch, HIP trees were much more likely to die than LIP or BHIP trees. 5 Two other factors influenced tree mortality. Past stress that reduced the tree growth a few years prior to the start of the experiment was shown to alter the tree's ability to cope with defoliation. Oak mildew selectively infected the defoliated trees and increased the severity of the defoliation stress. 6 Thus, trees subjected to high level of A. gallica inoculum had a lower ability to overcome the defoliation stress. These findings support the forest decline models developed by Manion in 1991 and show that it is important to take into account the role of opportunistic pathogens in tree mortality processes.

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Spatial pattern of the density of Armillaria epiphytic rhizomorphs on tree collar in an oak stand

Cited by 6 publications

References 24 publications

Occurrence of Hymenoscyphus pseudoalbidus on infected ash logs

Occurrence of Hymenoscyphus pseudoalbidus on infected ash logs

Ecology of Armillaria species in managed forests and plantations in Serbia

Role of an opportunistic pathogen in the decline of stressed oak trees

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