Fig 3 - uploaded by Paolo Gonthier
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Mycelia of Heterobasidion spp. (left), mycelia (white arrow) and rhizomorphs (black arrow) of Armillaria spp. (right) beneath the bark.
Source publication
Specific scope
This Standard describes a diagnostic protocol for Heterobasidion irregulare .11 Use of brand names of chemicals or equipment in these EPPO Standards implies no approval of them to the exclusion of others that may also be suitable.
This Standard should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols .
Specific ap...
Contexts in source publication
Context 1
... of infected roots or at the tree collar (Greig, 1998). Although this cannot be regarded as a reliable diagnostic feature of the disease, it is generally sufficient to discriminate between Heterobasidion root rots and Armillaria root rots, whose signs consist of a thicker mycelium and/or the presence of rhizomorphs (Guillaumin & Legrand, 2013) (Fig. 3). Conversely, the features of the mycelium beneath the bark do not allow a distinction to be made between H. irregulare and other root rot fungi, including H. annosum ...
Context 2
... from other fungi (Fig. 5). However, macromorphological and micromorphological characters of cultures are not sufficiently divergent to discriminate H. irregulare from other Heterobasidion species (Mitchelson & Korhonen, 1998). & Garbelotto, 2010), perennial, typically in the form of brackets (shelf-shaped) or resupinate, and rubbery in texture (Fig. 3). The top surface, if present, is reddish or dark brown (tobacco brown) in colour and becomes darker with age. The margin is distinct and white. The lower surface is characterized by numerous small pores and is white or cream coloured. Incipient fruiting bodies may form under the bark or on roots of windblown trees. These are small in ...
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Citations
Invasions by alien pathogens are a major threat to forest conservation. The North American fungal pathogen of conifers Heterobasidion irregulare , inadvertently introduced in Central Italy in the 1940s, has been spreading causing high mortality of Italian stone pine ( Pinus pinea ). While invading newfound niches, H. irregulare has established itself in the current range of the native congener H. annosum . The aims of this study were to determine whether in time: (I) H. irregulare populations may be increasing in size; (II) H. irregulare may be replacing H. annosum , rather than simply coexisting with it; and, (III) H. annosum may disappear in forests infested by H. irregulare . The presence, abundance and distribution of H. annosum and H. irregulare were assessed through an aerobiological assay replicated ten years apart in a forest in which both species have been coexisting. Replacement index (RI), Markov chains and geometric progressions were used to model the interspecific interaction between the two species and to assess the invasiveness of H. irregulare . Results showed that, in 10 years, the incidence of H. annosum dropped from 39.4 to 6.1%, while that of H. irregulare increased from 57.6 to 81.8%, with the alien pathogen replacing the native species (RI = 84.6%) and spreading at a maximum rate of 139 ha/year. Although our models show that the extinction of H. annosum may be unlikely, the ability of H. irregulare to replace it suggests the alien pathogen may also readily colonize those parts of Europe where H. annosum is more abundant than in Central Italy.
