Alternaria infectoria and Stemphylium herbarum, two new pathogens of pyrethrum (Tanacetum cinerariifolium) in Australia

Abstract

Perithecia at the base of dead flower stems of pyrethrum (Tanacetum cinerariifolium) plants in yield-decline affected fields of northern Tasmania were identified as Alternaria infectoria and Stemphylium herbarum. Identification was based on morphological description of cultures established from single ascospores; and conidiospores; ascospore shape and septation; and multigene phylogenetic analyses using the internal transcribed spacer (ITS) region, translation elongation factor 1-α (EF1), polymerase II second largest subunit (RPB2) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) genes. Stemphylium herbarum produced necrotic leaf lesions on both sides of the spray inoculated pyrethrum le..