, Volume 115, Issue 3, pp 151–161 | Cite as

Ophiostoma novo-ulmi sp. nov., causative agent of current Dutch elm disease pandemics

  • C. M. Brasier


The aggressive subgroup of the Dutch elm disease pathogen Ophiostoma ulmi (Buism.) Nannf. syn. Ceratocystis ulmi (Buism.) Moreau is named as a new species, O. novo-ulmi, and is thereby separated from the ‘old’ non-aggressive subgroup, which is retained as O. ulmi. O. novo-ulmi differs from O. ulmi in colony morphology, growth rate, optimum temperature for growth, perithecial neck length, pathogenicity to elm, bark colonising ability, cerato-ulmin protein production, synnemetal and protoperithecial production, mating type frequency, protein and isozyme polymorphisms, mitochondrial DNA and nuclear DNA polymorphisms, and mitochondrial DNA size. In addition, a strong unidirectional fertility barrier operates between the two species, while their hybrids show remarkable variation, poor fitness, and many are infertile. These aspects are summarised. New information on perithecial dimensions is presented. O. ulmi is redefined and a neotype designated. The status of the Eurasian and North American races of O. novo-ulmi is currently under investigation.

Key words

Ophiostoma ulmi Ophiostoma novo-ulmi Ceratocystis ulmi Dutch elm disease aggressive non-aggressive North American race Eurasian race 



Eurasian race


North American race


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Copyright information

© Kluwer Academic Publishers 1991

Authors and Affiliations

  • C. M. Brasier
    • 1
  1. 1.Forest Research Station, Alice Holt LodgeFarnhamUK

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