An experiment was conducted to determine the impact of six aqueous leaf extract; Vinca rosea, Datura stramonium ,Tagetes erecta, Aambrosia maritima, Ocimum basilicum , Bougainvillea spectabilis alone or combined with the nematophagous fungus; Paecilomyces lilacinus against the root-knot nematode, Meloidogyne javanica on potato(Solanum tuberosum) cv. Diamant under greenhouse conditions in Egypt. Results indicated that the most treatments tested obviously caused remarkable increase in potato plant growth with different degrees. The combination treatment of P. lilacinus + D. stramonium together revealed the highest value of percentage increase of the whole plant fresh weight (78.1 %), while the treatment of O. basilicum alone gave the lowest value of percentage increase of the whole plant fresh weight (23.8 %) . In addition, treatments singly or combined increased fresh weight and length of the whole plants as well as weight of potato tubers.
The combination of P. lilacinus + D. stramonium showed the highest efficacy in reducing the nematode population in both soil and roots also . On the other hand; the treatment of P.lilacinus alonel showed the least effect. The combing effect of P. lilacinus + D. stramonium induced a remarkable reduction in the nematode build up and improved both plant growth and tuber weight of potato plants in relation to nematode alone.