Inoculation methods for assessing resistance in wheat to crown rot caused by Fusarium graminearum group 1

Abstract

A range of inocululatron methods for assessing resistance in wheat to crown rot caused by Fusarium graminearum Group 1 was evaluated in the glasshouse and in the field. When grain was colonized with the pathogen, ground and applied with the seed at planting or spread around young plants as an aqueous suspension, high levels of crown rot were produced, but resistance (usually measured as per cent diseased plants or tillers) was still expressed. Similar results were achieved with induced field inoculum obtained by inoculating an area of wheat to obtain a high incidence of disease and incorporating the stubble into the soil. Natural field inoculum and inoculation of seed with spores produced lower levels of disease, although differentiation of resistant and susceptible cultivars was still possible. Other methods, suitable only for plants in pots and often for more specific purposes (for example, for inoculation at different stages of plant growth) were also studied. Resistance was best expressed where inoculum was applied onto or into soil, rather than directly onto or into plants. Currently, the resistance of all potential cultivars for release in Queensland is assessed in the field by sowing seed dusted with benomyl into furrows along which ground, colonized grain is distributed. Crown rot severity is then determined at maturity.