Aerial distribution of the root-rot fungus Fomes annosus (Fr.) Cooke in Finland

Abstract

F. annosus diaspores collected from Spruce stands in three regions of Finland were recorded at weekly or fortnightly intervals throughout 1968. Diaspores fell during the 24-hour periods almost continuously from April to Nov., but deposition was heaviest from late May to the end of Oct. Correlations were found between deposition of diaspores and air temperature, air humidity, wind velocity, and number of hours of bright sunshine. The fall of diaspores decreased with increasing distance from sporophores, but some diaspores were trapped over the open sea, 50-500 km. from a possible source. The aerial distribution of diaspores of two fungi antagonistic to F. annosus (Peniophora gigantea, and Trichoderma viride) was also investigated. The diaspores of P. gigantea fell at roughly the same seasons as those of F. annosus, and hence this fungus may reduce the damage caused by the latter. The fall of T. viride diaspores was less profuse and less continuous. Results are illustrated in tables and graphs.