Emerging Pest Alert

Sap stain fungi of conifers of potential quarantine concern to North America.

Scientific Name: Ceratocystis species

Describer: nan

Common Name: Sap Stain or Blue Stain Fungi

Title: Sap stain fungi of conifers of potential quarantine concern to North America.


Significance: The genus Ceratocystis includes a number of important bark beetle-vectored plant pathogens that are associated with sap stain in both angiosperms and gymnosperms. Using DNA sequence data and isozyme profiles, a large number of species belonging to this genus can be grouped together within the "C. coerulescens complex". However, two species, C. polonica and C. laricicola, which represent two distinct ecological entities, are difficult to differentiate, and were the focus of this recent study by Marin et al.

Both C. polonica and C. laricicola are present in Japan and are known as aggressive vascular stain pathogens that cause intensive and extensive blue stain in the sapwood of bark beetle infested spruce and larch trees. This damage can result in substantial economic losses due to quality decline of timber and wood products. Studies to determine the identity of Japanese isolates of these types of fungi were carried out using various morphological and molecular methods. Results indicated that in addition to C. polonica and C. laricicola, a third species, designated C. fujiensis could also be differentiated.

Issues of Concern: According to the authors, these three Ceratocystis species, together with their bark beetle vectors, are not known to occur in North America and represent a substantial quarantine threat to forestry on the continent. It is suggested that great care should be taken to avoid introduction of these organisms as little is known of their ecological behavior outside their natural habitat.

Pathways: Untreated wood products, packing or dunnage (PAS editor guess)

Hosts: Ceratocystis polonica causes blue stain on Norway spruce (Picea abies) and other spruce species, such as Yezo (P. jezoensis) and Sachalin (P. glehnii). Inoculation studies have shown that C. polonica is pathogenic to Douglas fir (Pseudotsuga menziesii) as well as North American spruce species (Picea sitchensis, P. glauca, and P. mariana).

Ceratocystis laricicola infests various larch species (e.g., Larix decidua, L. kaempferi).

Vector(s)/Dispersal: Ceratocystis polonica has been found in association with Ips typographus japonicus (an Asian subspecies), I. typographus, I. amitinus and I. duplicatus while Ceratocystis laricicola has a close association with the bark beetle Ips cembrae.

Distribution: Ceratocystis polonica and C. laricicola have been found in Europe (country(ies) not mentioned in paper) and Japan.

Comments: If you have any additional information about the distribution of these species or known pathways, please let us know.


Marin, M., Preisig, O., Wingfield, B.D., Kirisits, T., Yamaoka, Y. and M.J. Wingfield. 2005. Phenotypic and DNA sequence data comparisons reveal three discrete species in the Ceratocystis polonica species complex. Mycological Research Vol. 109(10):1137-1148.