Fusarium resistance in Gladiolus: the development of a screening assay

Fusarium oxysporum f.sp. gladioli is a major pathogen of Gladiolus and resistance to this fungus is needed. A standardized screening assay to assess resistance levels in breeding selections must be developed. Corms of cultivars, ranging from susceptible to resistant, were planted either in soil infested with various inoculum levels or incubated in vitro after wound inoculation. The soilgrown corms were rated using relative length of the shoots and average disease rating. In vitro incubated corms were evaluated visually after 6 weeks. All parameters produced similar results. It was concluded that the relative length of shoots of corms after 8 weeks of growing in soil with a high inoculum level combined with the assessment of the average disease rating of the corms after either 8 or 20 weeks is an effective screening assay