Suitability of ten plant baits for the rapid detection of pathogenic Pythium species in hydroponic crops

Ten types of plant baits were tested in the laboratory to assess their capa city to detect pathogenic Pythium species. These were orange tree leaves, t omato leaves, pepper leaves, geranium leaves, Bermuda grass leaves, pine ne edles, immature carnation petals, hemp-seed cotyledons, pepper and cucumber fruits. The Pythium spp. tested were P. aphanidermatum, P. irregulare and Pythium 'group F' from hydroponic market garden crops in the Poniente regio n of Almeria (south-east Spain). The test consisted of observing the veloci ty at which five baits were colonized and the day of colonization of the fi rst bait. Results indicated that the slowest baits to be infected were imma ture carnation petals and pine needles. These two, together with Bermuda gr ass leaves, were also the baits infected in lowest number, such that practi cally no further infection was produced in the baits after the fifth day of contact with the inoculated water. The other plant baits tested were equal ly suitable for detection of Pythium spp. over the first two days, although only orange leaves and hemp-seed cotyledons were infected on the first day .