Fungi colonizing Scots-pine cone scales and seeds and their pathogenicity

Fungi were isolated from the cone scales and seeds of Scots pine using plating an male-extract agar and/or the standard blotter method in a Jacobsen's apparatus. Alternaria alternata, Epicoccum purpurascens and Ulocladium atrum were isolated from damping-off seedlings germinating on agar or filter paper, but, in pathogenicity tests with pear-sand (1:3) growth substrate, they were not pathogenic. All the Fusarium species isolated were pathogenic in growth substrate. Some F. avenaceum colonies formed no aerial hyphae and they proved to be a mixed culture of the fungus, a fluorescent Pseudomonas sp., and a gram-negative bacterium. The bacterial associates appeared to increase the pathogenicity of F. avenaceum. All the micro-organisms tested were more pathogenic in sterilized than in unsterilized pear-sand substrate.