Abstract
The factors producing the white line were studied in an attempt to develop the simplified methods of diagnosing of cultivated mushrooms infected with Pseudomonas tolaasii. White line were produced when P. tolaasii and Pseudomonas sp. (white line reacting organism : WLRO) were dually cultured on Pseudomonas agar F, King's B and TMGA medium. White lines produced on a PAF, and TMGA medium were clear and stable, but strains that can not be produced on a King's B medium had existed, and it was observed that white lines formed, if any, were not quite clear and tended to have disappeared when incubation was prolonged. When a distance between P. tolaasii and WLRO was within 20mm, clear white lines were produced, and the shorter the distance, the earlier the production was achieved. Only strains of P. tolaasii having pathogenicity in mushroom fruit bodies produced white lines, while none pathogenic mutants no longer had their capability of producing white lines. The capability of producing white lines was recognized in neither Erwinia spp nor epiphytic bacteria grown in mushroom species. When the tissue of diseased fruit bodies were dually cultured on PAF with WLRO, approximately 80% of tissues had definitely produced white lines 2days thereafter, and it was possible to diagnose the bacterial blotch disease directly without isolation of P. tolaasii.
