Baiting method for estimating the relative inoculum density of the white root rot fungus in soil

抄録

A baiting method using Lupinus luteus was applied to the relative estimation of the inoculum density of the white root rot fungus, Rosellinia necatrix in soil. Chips (20 g in dry weight) of dormant twigs of Japanese pear colonized by the fungus were serially diluted with 5 L of an orchard soil and incubated for a week. Thirty seeds of L. luteus were sowed at 5 cm intervals into the infested soil, and the plants were grown at 25 ℃ in a greenhouse during a month. Infection on the plants was then checked. Necrotic and/or rotten legions were observed on the hypocotyls and/or tap roots. There was a significant correlation between the dilution rate of the inoculum and the detection frequency of the white root rot fungus in artificially infested soil. This method is considered to be useful for estimating the inoculum density of the white root rot fungus in field soil.