In 1964 lesions associated with Alternaria alternata (syn. A. tenuis Nees) were found on a number of varieties of strawberries at the Horticultural Research Centre, Levin, and again in 1966 on the varieties 'Redgauntlet' and 'Talisman' in commercial planting in Nelson. Morton (1964) described A. alternata and its occurrence in New Zealand, listing it as a saprophyte on a large number of host plants. In the literature there are references to A. alternata occurring as a primary pathogen. Munnecke (1956) and Fletcher and Ryan (1966) report it on geranium (Pelargonium spp.); Wilcox (1963) reported it on Lobelia sp. Tests carried out in the glasshouse at Plant Diseases Division, Auckland, showed cultures of this fungus to be pathogenic to strawberries, especially the varieties 'Redgauntlet' and 'Talisman'; therefore it is described as A. alternata (Fr.) Keissler f.sp. fragariae.

Lesions on leaves orbicular, 2-5 mm diam., brown with dark reddish purple margins, under surfaces greyish brown. Conidiophores formed singly or in clusters on superficial mycelium on under surfaces of leaves, 17-90 X 3.5-4.5 um, smooth, septate with few branches, geniculate with many pronounced scars, poroid, terminal segments always slightly swollen. Conidia borne singly or in chains of up to 8 spores, brown, sometimes lightly coloured, coarsely echinulate, globose, ovate, or obpyriform, often with a short beak multiseptate, muriform, variable in size and septation, usually 20-35 X 8.5-12 um with 3-6 transverse septa and with 0--4 longitudinal septa.

In culture, conidia were freely produced among the brown superficial floccose mycelium. Conidiophores were produced singly as short lateral branches up to 30 um long with 2-6 geniculations. Chains were formed when conidia were still attached to the conidiophores germinated at the apical beak to form other conidia. At times the apical beak germinated to form a short conidiophore which in turn bore one or more conidia.

Morphologically this variety cannot be separated from A. alternata. No perithecia have been found either in culture or on strawberry leaves.