Phomopsis subordinaria and associated stalk disease in natural populations of Plantago lanceolate

Abstract

Natural populations of Plantago lanceolata L. can be infected by the fungus Phomopsis subordinaria (Desm.) Trav., which causes a stalk disease. Inoculation experiments revealed that the fungus needs a wound to enter the plant tissue. Symptoms of the disease in the field and from inoculation experiments in the greenhouse are described and the taxonomic position of the fungus is discussed. The pathogen could not be isolated from other plant species in heavily infected Pl. lanceolata populations and can be regarded as specialized on Pl. lanceolata. Other species of the genus Plantago differed considerably in their susceptibility to the disease. Comparison of Pl. lanceolata genotypes indicated that there is variation in susceptibility among host genotypes. Because the disease may reduce the production of viable seeds, the possibility of natural selection for resistance in the host is considered.