Survival and spread of the endophyte Stagonospora pteridiicola in Pteridium aquilinum, other ferns and some flowering plants.

Pteridium aquilinum (L.) Kuhn was sampled for colonization by Stagonospora pteridiicola in Great Britain, Hungary and Australia. British samples gave the highest incidence of 68% during September and 12% at the beginning of the growing season. Hungarian samples showed a similar frequency. The fungus was not found in Australian bracken. Five field-collected fern species other than bracken did not contain the fungus in May when bracken already had a colonisation frequency of 12% in the pinnules. Sampling after the bracken had died in November demonstrated that the fungus had continued growth as a saprobe. Glasshouse-grown bracken sprayed with a spore suspension showed 96% colonization after 21 d, whereas four fern species and five flowering plants, similarly treated, gave colonization frequencies of 0-3%. Other glasshouse-grown bracken, similarly sprayed, showed that colonization declined over 5 months from 75% to 40%, and that the fungus showed little spread into fresh unsprayed growth on these plants. The possible species specificity of the fungus is discussed.