The suppression of Meloidogyne incognita by marigolds differed among six marigold cultivars and five soil temperatures. Tagetes signata (syn. T. tenuifolia) cv. Tangerine Gem and the Tagetes hybrid Polynema allowed reproduction and root galling when grown at 30 degrees C, and should not be used for control of M. incognita at temperatures close to 30 degrees C. Tagetes patula cultivars Single Gold and Tangerine and T. erecta Flor de Muerto, when grown within a 20-30 degrees C soil temperature range, significantly reduced root galling and nematode infestation of subsequent tomato compared to tomato following fallow. When grown at 10 degrees C or 15 degrees C, only one of the tested marigold cultivars (T. erecta CrackerJack at 15 degrees C) reduced M. incognita infection of subsequent tomato compared to tomato after fallow. Marigolds should be grown at soil temperatures above 15 degrees C to suppress M. incognita infection of a subsequent crop.
Keywords: Meloidogyne incognita; Tagetes; marigold; nematode; root-knot nematodes; suppression; temperature.