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Evaluation of selective media and bait methods for estimating Phytophthora cactorum in apple orchard soils |
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| Authors: | D C HARRIS ANNA BIELENIN |
| Institution: | East Malling Research Station, Maidstone, Kent ME19 6BJ, UK;Research Institute of Pomology and Floriculture, 96-100 Skierniewice, Poland |
| Abstract: | Soil plating, with a specially devised selective medium, gave estimates of Phytophthora cactorum in an East Mailing Research Station apple orchard soil up to three times those obtained by dilution and baiting with apple seedlings or cotyledons and using the most probable number analysis. When the same techniques were applied to a range of soils from apple orchards in south-east England with a history of P. cactorum diseases the plating method failed in most instances, mainly because Pythium spp. rapidly swamped the plates. The dilution/baiting method was applicable to all soils though there was a tendency to underestimate because of anomalous results at lower soil dilutions. Oospores were the only propagules which could be confirmed as sources of P. cactorum colonies on soil isolation plates. |
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