Reaction of fifteen malvaceous plant cultivars to root-knot nematodes, Meloidogyne spp.

Resistance of malvaceous crop plants to root-knot nematodes (Meloidogyne spp.) has been the subject of several studies. Wiles (1957) found that M. hapla, M. arenaria and M. javanica caused no visible galling on upland cotton (Cossypium hirsutum L.) cvs. Auburn 56, Coker 100, Alabama Hybrid 81-14 and Empire. Minton (1962) studied the development of root-knot nematodes in 7 cotton cultivars and showed that M. incognita acrita matured in cvs. Rowden, Auburn 56, Mexican (C. hirsutum) and a wild selection of C. barbadense L.; M. incognita matured in Rowden, Empire and Auburn 56, whereas M. arenaria matured in Rowden only. Brodie and Cooper (1964) demonstrated that isolates of M. incognita, M. arena ria, M. javanica and M. hapla were able to penetrate roots of upland cotton (C. hirsutum) seedlings in equal numbers and significantly reduce the growth of seedlings. Only one isolate of M. incognita reached the egg-laying stage, while the other isolates did not develop beyond the second larval stage. Khalil (1977) detected an isolate of M. javanica which reproduced in and reduced the growth of the cotton (C. barbadense) cv. Giza 69. Pate et al. (1958) reported that kenaf (Hibiscus cannabinus L.) was extremely susceptible to root-knot nematodes. Wilson and Summers (1966) detected a wild strain of kenaf from Kenya possessing a significant level of resistance to root-knot nematodes; they also found that the fibre-type cultivars of roselle (H. sabdariffa L.) were moderately to highly resistant. Adeniji (1970) reported that all of the 8 roselle cultivars that he tested were resistant to M. incognita acrita, M. incognita, M. arenaria and M. javanica. Minton and Adamson (1979) found that the roselle breeding line A59-56 was highly resistant to M. javanica and M. arenaria. The present study was undertaken to determine the reaction of 15 malvaceous plant cultivars to the common species and races of root-knot nematodes in northern Egypt.