Population biology of the forest pathogen Heterbasidion annosum:implications for forest management

  • Authors: Garbelotto, M.; Otrosina, W.J.; Cobb, F.W.; Bruns, T.D.
  • Publication Year: 1998
  • Publication Series: Scientific Journal (JRNL)
  • Source: In: Proceedings of the 46th annual meeting; California Forest Pest Council; 1997 November 12-13; Sacramento, CA. [Place of publication unknown]: [Publisher unknown]: p. 24-35.

Abstract

Heterobasidion annosumranks as one of the most destructive pathogens in North American coniferous forests. Understanding the population biology of this fungus may facilitate understanding not only the basic biology of the organism, but also the general patterns of disease development, modes of host-pathogen interactions, effect of management practices on the dynamics of dispersal, establishment, and evolution of the pathogen and/or the host. In turn, this information allows for a more profound understanding of the general health of an ecosystem, leading to more refined and targeted management practices. In the case of H. annosum, previous research has elucidated aspects of the etiology and spread of disease for host species such as European pines and spruces. In these instances, primary stump infection and root-to-root secondary contagion appear to be major avenues of disease development. No information is available on the true fir/H. annosum pathosystem for Western North America, although the pathogen is increasingly affecting this tree species. Because of the different hosts involved, of the different biogeographic region, and of the significant genetic divergence among groups of H. annosum characterized by different host preferences, it is not possible to extrapolate results from other regions of the world to Western North America, and in particular to California. Two genetically distinct intersterility groups (ISGs) of the fungus are present in California: the S ISG mostly infects true firs, hemlocks, Douglas-firs, and sequoias, while the P ISG is found mostly on pines, incense cedars, and junipers. These two ISGs are known to mate in the laboratory, but evidence of mating in nature has been gathered only recently. Still, there is no understanding of the frequency of mating and gene flow between the two groups. In these last years the authors? research effort has been to elucidate the dynamics of fungal establishment and spread in California mixed conifer forests with a predominance of true fir. The scale of analyses has ranged from small scale studies designed to understand the genetic structure of pathogen populations in individual mortality centers to larger analysis at the broader regional level; the latter analyses have been designed to shed light on medium to long distance gene flow between demes of one ISG and even potentially between ISGs. One focus of the authors has been to relate the genetic structure of this organism to forest stand characteristics in the attempt to understand the impact of forest to understand the impact of forest management on the population biology of this organism, on the epidemiology of the disease, and on the severity of the mortality associated with this pathogen.

  • Citation: Garbelotto, M.; Otrosina, W.J.; Cobb, F.W.; Bruns, T.D. 1998. Population biology of the forest pathogen Heterbasidion annosum:implications for forest management. In: Proceedings of the 46th annual meeting; California Forest Pest Council; 1997 November 12-13; Sacramento, CA. [Place of publication unknown]: [Publisher unknown]: p. 24-35.
  • Posted Date: January 1, 2000
  • Modified Date: August 22, 2006
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