Burn Spot Disease (Fungus Disease) of Crayfish


Category 1 (Not Reported in Canada)

Common, generally accepted names of the organism or disease agent

Burn spot disease, Fungus disease.

Scientific name or taxonomic affiliation

Ramularia astaci, Didymaria cambari and Fusarium spp.

Geographic distribution

Widespread in Europe.

Host species

Astacus astacus, Orconectes limnosus.

Impact on the host

Fungal infection of exoskeleton and gills. Ramularia infection rates reported up to 85% possibly with significant mortality. Didymaria usually causes smaller lesions (up to 5 mm in diameter) and infects the uropods.

Diagnostic techniques

Gross Observations: Melanized lesions on calcified areas of exoskeleton and gills may be up to 1 cm across, brown-black in colour with red margins and eroded in the centre. Hyphae may invade the gills and muscular system.

Wet Mounts: Examine lesions for mycelia.

Methods of control

No known methods of treatment or control.


Alderman, D.J. and J.L. Polglase. 1988. Pathogens, parasites and commensals. In: D.M. Holdich and R.S. Lowery (eds.). Freshwater Crayfish ­ Biology, Management and Exploitation. Timber Press, OR., p. 186-187.

Sparks, A.K. 1985. Synopsis of Invertebrate Pathology Exclusive of Insects. Elsevier Science Publishing Co. Inc., Amsterdam. p. 226-227.

Unestam, T. 1973. Significance of diseases on freshwater crayfish. In: S. Abrahamsson (ed.). Freshwater Crayfish ­ Papers from the First International Symposium on Freshwater Crayfish. Austria 1972. Studentlitteratur, Lund, p. 135-150.

Citation Information

Bower, S.M., McGladdery, S.E., Price, I.M. (1994): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Burn Spot Disease (Fungus Disease) of Crayfish.

Date last revised: Fall 1994
Comments to Susan Bower

Date modified: