الفهرس 
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Abstract
-”A survey of plant-parasitic nematodes gives information about parasitic nematodes distribution and delivers supplementary information to agronomists about phyto-nematodes importance. A survey of four solanaceous plants i.e., potato, tomato, pepper, and eggplant grown within three counties in Dakahlia governorate i.e., El-Sinbillawain, Mansoura, and Aga revealed the presence of 10 nematode genera i.e., Dorylaimus, Helicotylenchus, Hoplolaimus, Meloidogyne, Pratylenchus, Rotylenchulus, Trichodorus, Tylenchorhynchus, Tylenchus and Xiphinema. The root-knot nematode, Meloidogyne spp. appeared to be the key pest as its documented 108 times with a total percent incidence of 72.0 %, whereas, the nematode genera, Rotylenchulus, and Trichodorus exhibited modest spreading as they occurred at rates of 55 and 50 times with percent incidence of 36.6 and 33.3%, respectively. On the other hand, Helicotylenchus and Xiphinema had the lowermost values of spreading as they occurred at the rate of 13 times with a percent incidence of 8.6 % for each one. However, Meloidogyne spp. showed a greater rate of occurrence in clayey soil texture at El-Sinbillawain county with the value of occurrence of 75.8%. Potato and eggplants encountered the highest nematode genera numbers with an equal number (9), followed by tomato (8), while pepper has the lowest number (7) respectively. As for the effect of four chemical inducers at four concentrations on egg hatching and juvenile mortality of M. incognita, in vitro. All tested four chemical inducers i.e., methyl salicylate, silicon, isonicotinic acid, and tannic acid recorded a significant increase in the rate of egg hatching inhibition and juvenile mortality according to the type and concentration of chemical inducers after three times intervals. In general, increasing chemical inducer concentration from 2 to 8 mM led to an increase in the rate of inhibiting M. incognita egg hatching and an increase in juvenile mortality rate compared to the control. Methyl salicylate recorded the best results in inhibiting the rate of hatching eggs, which ranged from 71% for the lowest concentration (2 mM) to 83.0% for the highest concentration (8 mM) after three times intervals. Meanwhile, the treatment with isotonic, tannic acid, and silicon recorded moderately inhibitory rates for egg hatching with values ranging from 58% for the lowest concentration of tannic acid to 79.0% for the highest concentration of silicon, respectively. Similar results were achieved by methyl salicylate as recorded as the best results in increasing the rate of M. incognita juveniles mortality, which ranged from 24.7% for the lowest concentration (2 mM) to 90.7% for the highest concentration (8 mM) after three times intervals. Meanwhile, the treatment with isotonic, tannic acid and silicon recorded moderate juvenile mortality rates with values ranging from 6.7% for the lowest concentration of isotonic to 70.7% for the highest concentration of silicon, respectively as compared to control. With reference to the effect of five plant extracts i.e., Conyza dioscoridis, C. acutum, C. rotundus, I. cylindrica, M. pulegium at three concentrations on egg hatching and juveniles mortality of M. incognita, in vitro. It was evident that all plant extracts achieved a significant increase in the rate of egg hatching inhibition according to the extract plant species and concentration after three times intervals. In general, there was a positive correlation between the concentration of the plant extract and the percentage inhibition of egg hatching and juveniles mortality as there was a high inhibition hatching rate and juveniles mortality values with the higher concentration used of the plant extract. C. dioscoridis extract achieved the best results in inhibiting the rate of hatching eggs, which ranged from 89.0% for the lowest concentration (1 mM) to 91.0 % for the highest concentration (10 mM) after three times intervals. Meanwhile, the treatment with other extracts recorded moderately inhibitory rates for egg hatching with values ranging from 56.0% for the lowest concentration of I.cylindrica to 83.0% for the highest concentration of C. acutum, respectively. Similarly, C.dioscoridis recorded the best results in increasing the rate of M. incognita juvenile mortality, which ranged from 6.7% for the lowest concentration (1 mM) to 53.3% for the highest concentration (10 mM) after three times intervals. Meanwhile, the treatment with other plant extracts recorded moderately juvenile mortality rates with values ranging from 6.7% for the lowest concentration of C. acutum to 29.3% for the highest concentration of I. cylindrica, respectively as compared to control. With respect to the efficacy of methyl salicylate and Cyperus rotundus application compared with oxamyl at the recommended dose against the root-knot nematode M. incognita infecting pepper plant cv. California under greenhouse conditions. Results indicated that the two tested materials were obviously found to be more effective in improving plant growth parameters with or without nematodes inocula as compared with nematodes alone. The application of C. dioscoridis extracts surpassed the application of methyl salicylate with or without nematodes inocula in improving plant growth parameters i.e., total plant length (50.52 and 43.76%) and fresh weight (81.25 and 76.80%), number of leaves (57.8 and 44.4%) as well as shoot dry weight (77.4 and 54.8%%), respectively for C. rotundus extract with or without nematodes inocula when compared to that of nematode alone. It was obvious that nematode population density and rate of nematode reproduction as well were significantly affected by the two tested materials achieving similar results for nematode criteria that amounted to 94.2, 95.1, 95.4, 95.2, 98.3, and 97.4% for reduction of final nematode population, galls, and egg masses number respectively as compared to nematode alone. Oxamyl as a systemic standard nematicide achieved the lowest value of nematode multiplication rate averaging 0.03 compared to nematode alone. It is interesting to observe that the indices of galls and egg masses of the tested plant applications ranged from 1 to 3 vs. 5 for nematode alone, respectively. Meanwhile, oxamyl as nematicide gave the lowest value of root gall and egg masses indices that amounted to 1 vs. 5 for nematode alone, respectively. Finally, HPLC analysis of crude methanol extracts of five weed extracts i.e., Conyza dioscoridis, C. acutum, C. rotundus, I. cylindrica, M.pulegium revealed the presence of the major active compounds with nematicidal properties. e-Vanillic acid was the main phenolic compound in all methanol extracts at 11.498 mg/g (M. pulegium), 10.372 mg/g (C. dioscoridis), 8.280 mg/g (C. acutum), 4.725 mg/g (C.rotundus), and 2.367 mg/g (I.cylindrica).