A leaf disc assay for determining resistance of taro to <i>Phytophthora colocasiae</i>

Abstract

Phytophthora colocasiae is a destructive fungal pathogen of taro (Colocasia esculenta) which causes taro leaf blight This disease destroyed Samoas taro export industry and led to local food shortages following introduction of the pathogen in 1993 In support of a Pacific regional taro resistance breeding programme laboratory studies in New Zealand aimed to develop a leaf disc bioassay for identifying taro genotypes with disease tolerance A medium has been developed that will retard senescence of the leaf discs for over 14 days The rate of leaf disc infection and subsequent lesion development varied with incubation temperature leaf age and taro cultivar An understanding of these factors and the variation they cause has resulted in a laboratory leaf disc assay for testing resistance of different taro cultivars to taro leaf blight