Field observations on the reaction of medicinal plants to root-knot nematodes in Isfahan, Iran.
A field survey to assess the reaction of 42 medicinal plants to root-knot nematodes was conducted in three regions of Isfahan Province, Iran during 2002-2005. The severity of the infection and the host status of the plants were estimated according to a galling scale, and number of eggs and juveniles in roots and soil. Out of twenty five medicinal plant species cultivated in Dastgerd station, 21 species (pot marigold, horehound (Marabium vulgare L.)), starflower (Echium amoenum), borage, Klamath weed (Hyperium perforatum L.), absinthium (Artemisia absinthium L.), meadow salsify (Tragopogon pratensis), camomile, garden thyme, Greater burdock (Arctium lappa), common sage, Jerusalem artichoke, Pelargonium, rosemary, milk thistle (Silybium marianum), lemon balm (Melissa officinalis L.), madder (Rubia tinctorum L.), yarrow, common lavender, alehoof (Nepeta hederacea) and celery were infected by Meloidogyne. javanica to varying degrees while four species (fennel, spearmint, valerian and yarrow) were not. In Najafabad station, out of twenty medicinal plant species, five (common rue (Ruta graveloens L.)), Syrian beancaper (Zygophyllum sp.), Greater burdock, pot marigold and hempseed (Cannabis saliva L.) were infected by M. javanica and the remaining fifteen (aniseed, blueweed (Echium sp.)), cardoon (Cynara drancunculus), dragonhead (Dracocephalm kotschy), wild basil, salad burnet (Sanguisorba minor), hyssop, iris, Klamath weed, lamb's ear (Stachys byzanthina), milk thistle, Moldavian balm (Dracocephalum moldavica L.), motherwort (Leonurus cardiaca), oregano and peanut were free from this nematode. Out of 13 cultivated medicinal plant species in Kashan, seven (common lavender, yarrow, wormweed (Lavandula angustifolia L.)), black mulberry (Morus nigra), terracotta gazania (Gazania sp.) and century (Agave sp.) were infected by M. incognita. Most of the medicinal plants in these studies are reported to be new host records for M. javanica and M. incognita.