A Brushing Method of Inoculation for Screening Tomato Seedlings for Resistance to Septoria lycopersici. J. C. Tu, Agriculture Canada, Research Station, Harrow, Ontario N0R 1G0. V. Poysa, Agriculture Canada, Research Station, Harrow, Ontario N0R 1G0. Plant Dis. 74:294-297. Accepted for publication 17 October 1989. Copyright 1990 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-74-0294.

Screening of tomato (Lycopersicon esculentum) seedlings for resistance to Septoria lycopersici was more accurate by brush-inoculation of leaves than by dipping or spraying. An inoculum concentration of 10⁶ spores per milliliter or higher was applied to both sides of leaves with a camel’s-hair brush, pots containing inoculated seedlings were placed in shallow trays in a thin layer of water, and the inoculated seedlings were covered with a moisture-proof plastic canopy for 48 hr at 24 ± 2 C in a greenhouse. Differences in susceptibility were most evident 8 days after inoculation. Although more time-consuming than dipping or spraying, this method resulted in more uniform disease development and provided reliable differentiation between susceptible and resistant genotypes.