Under screen house conditions, two experiments were carried out to evaluate certain bacterium, Pseudomonas fluorescens isolates regarding reproductive potential of root-knot nematode, Meloidogyne incognita, infecting tomato or eggplant. Results on tomato revealed that, on the basis of average total percentages nematode reduction, the over topped results were gained with P. fluorescens (Pf2) which recorded the highest significant (P≤0.05) average nematode reduction (61.3%) and higher percentage reduction of females (77%) per plant. The second rank was obtained by Pf3 which reduced all nematode numbers as an average of 56.9%.On the basis of average total percentages plant growth and weight of fruit increases, four bacterial treatments can be ranked in a descending order as follows: Pf9 > Pf4>Pf1and Pf7, as they achieved the highest average total percentages increases of 96.0, 47.3, 38.2and 29.8%, respectively compared to other treatments and untreated check. Regarding to eggplant, the over topped results observed was achieved by P. fluorescens (Pf10) which recorded the highest average total nematode reduction (66.2%) with higher reduction of (J2s) in roots (89.9%) per plant and in soil (78.8%) per pot. The second rank was obtained by Pf9 and Pf2 where they reduced all nematode numbers as averages of 55.9% and 54.9%, respectively. Also Pseudomonas isolates enhanced the plant growth of eggplant, averages were found in a descending order as follows: Pf1 (20.0%), Pf9 (18.7%) and Pf10 (18.3%) . It is worthy to note that the most distinct growth criteria was fresh weight of roots as it achieved higher percentage increase (58.1%) by using Pf9 followed by Pf1 as it caused 40.6% increase compared to untreated check. The highest average percentage of fresh weight of shoot were recorded for Pf10 (26.4%) and Pf8 (22.1%). Whereas for dry weight Pf3 (29.8%) and Pf2 (19.1%). In conclusion, the tested biocontrol agent was efficient in controlling the root-knot nematode on tested plants.

Experiments in this investigation indicated that the tomato cv. 035 is moderately resistant to Meloidogyne incognita (Mi) and Fusarium oxysporum f. sp. lycopersici (Fol) since it supports a low population of Mi nematode and retarded fusarial damage in single infections while the plant vigor was unaffected adequately. This resistance was decreased as increased of inoculum levels (from 100 to 2000 IJ2) of Mi and (from 102 to 1010 propagules) of Fol indicating that this resistance is mainly density-dependent. However, co-infection by both pathogens a lesser margin of simulative effect on root galling and wilt severity was occurred. Therefore, wounding by invading IJ5 of Mi proved to be unimportant for establishment of Fol wilt fungus. The results indicated also that, the sequence of infection by nematodes and fungus can predispose the host plant to attack by the other. As with Mi pre infection, nematode causes changes in host that predispose it to fungal attack leading to severe wilt expression. Likewise, pre-infection with for allowed not only more nematode penetration but also more nematode developed than in fungus. Accordingly, the present results led to the fact that, the interactions between Mi nematode and Fol wilt fungus are physiological rather than physical.

Different agents were tested as inducing re-sistance factors in tomato plants against root-knot nematode Meloidogyne incognita. These agents include ethyl salicylic acid, (0.125 ml/l) jassmonic acid (0.125 ml/L) sincocin solution, (0.1%) agrispon solution (0.1%) water extract of mango malformed inflorescence (7.5%), coconut milk solution (2%) as root dipping during transplanting and spraying after one month from transplanting. Data obtained clearly indicated that sincocin solu-tion, extract of mango malformed inflorescence, agrispon solution and jassmonic acid led to a great reduction in disease severity, number of galls/ root, number of females/ root and number of egg masses/ root, followed by ethyl salicylic acid and coconut milk descending order. All tested agents did not affect juvenile's viability except mango malformed inflorescence extract and coco-nut milk solution which led to slight effect on juvenile viability. All tested agents increased plant growth in the presence of nematode inocula in comparison to untreated plants. In this respect coconut milk solution had the superior effect. Data indicated that the tested agents induced resistance in treated plant and the mechanisms of their mode of action needs further studies.