Powders of the aerial parts of thirteen Saudi wild plant species namely: Achillea fragrantissima, Anastatica hierochuntica, Brassica sinaica, Calotropis procera, Cleome rupicola, Ducrosia anethifolia, Fagonia bruguieri, Lactuca serriola, Pulicaria crispa, Reseda muricata, Salsola imbricata, Trichodesma africanum and Zygophyllum migahidii were screened for their nematicidal activity towards the root-knot nematode(Meloidogyne javanica) infecting common bean cv. Strike in a pot experiment under greenhouse conditions (35±5ºC). Plant powders were applied as amendments of nematode-infested soil at 0.3% (w/w), comparing to a treatment with the nematicide, Carbofuran 10%G (0.1g/pot), 7 days prior to planting. Nematode-free soil and nematode-infested soil were served as checks. All studied plant powders significantly reduced (P≤0.05) numbers of root galls, nematode egg masses, final nematode egg populations and reproduction factor on common beans, as compared to nematode check. Among them, C. rupicola, S. imbricata, T. africanum and Z. migahidii provided the maximum reductions of all disease parameters ranged from 82.0-96.4%, whereas F. bruguieri gave the minimum ones (33.9-40.4%). Meanwhile, application of Carbofuran 10% resulted in 88.0-90.8% reduction of all disease parameters. On the other hand, common bean growth of the most treatments significantly increased (P≤0.05), as compared to nematode check plants, and mostly to the nematicide-treated and healthy ones. Percentages of increase were ranged from 80.1 - 188.3% in shoots and 106.8 - 278.8% in roots. On the contrary, soil treatments with the powder of A. hierochuntica and Z. migahidii, showed little phytotoxicity symptoms on common beans. Powders of C. rupicola, S. imbricata, T. africanum and Z. migahidii achieved relative nematicidal efficacy ranged from 66.5 – 269.1% of Carbofuran 10%.
The current results recorded new wild plants in Saudi Arabia with a potential nematicidal activity against the root-knot nematode. They may be considering a safe source of new alternative nematicides.