UTILIZATION OF SOME BOTANICAL SUBSTANCES IN CONTROLLING THE ROOT-KNOT NEMATODE

Abstract

The nematicidal aetivity of extracts, essential oils , root exudates and their mixtures of Citros aurantium, Cyperus rotundus, Mentha spicata, Nigella sativa, Psidium guajava and Rosmarinus officina/is against Meliodogyne incognita in vitro and in pot experiments was assessed. Under in vitro, all treatments significantly exhibited variable mortality percentages showed various degrees of effects on M incognita juveniles, at different exposure times. Leaf or shoot extracts or oils were more toxic than those obtained from roots or stems of each plant. Essential oil of M spicata achieved the highest mortality percentages of M incognita juveniles; (71.7 %). The mixtures of C. rotundus (re) & R. officina/is (lo) and C. rotundus (re) & P. guajava (le), achieved the mortality percentage (78.7 %). after 48 h. exposure time. Synergism percentages ranged by 7.3 % to 49.5 %. Root exudates of C. rotundus achieved the highest mortality percent (39.0 %). The fantastic combined treatment was recorded by N sativa & R. officina/is root exudates; mortality percentage was 52.0% and synergism percentages ranged by 7.2 to 49.8. Hatchability of M incognita egg masses were significantly suppressed by the tested plant extracts and essential oils. The percent reduction of the hatched juveniles ranged by 40.0 %to 90.0 %. of N saliva (le) and R. officina/is (lo) achieved the lowest numbers of hatched juveniles; mean percent reduction was 83.3 %, 79.2% respectively. Root exudates of C. rotundus resulted in the highest percent reduction of the nematode egg hatching, (58.6 %). In a pot experiment, results showed that all applied treatments diminished penetration, gall formation, nwnbers of developmental stages, females, egg masses, 12 in soil and final population as well as fecundity and build -up of M incognita. The fantastic suppression of the nematode penetration, gall fonnation and rate of build-up was achieved by N sativa leaf extract and M spicata leaf essential oil while R officina/is root extract was the least effeetive treatment. Plant growth of the nematized tomato plants was significantly recovered by the tested plant extracts and essential oils, in most cases. The fantastic plant growth improvement, out of the tested treatments were resulted by N sativa root extract and M spicata leaf essential oil. All mixtures plant extracts and I or essential oils sueceeded in reducing rate of penetration, gall fonnation, nematode counts, fecundity and rate of build-up of M incognita. The percent synergism ranged by 0.43% to 49.5% and by 7.3 to 56.9% against rate of penetration and rate of build-up respectively. The mixture of C. aurantium (lo)& C. rotundus (re), M spicata Qo)& R officina/is (lo) and R. officina/is (lo) & P. guajava (le) achieved generally the highest percentages control of the nematode. Most of the tested mixtures improved plant growth of the infected plants. Root exudates of C. rotundus achieved the highest percentages reduetions of the nematode parameters. Moreover, the percentages enhancements in root growth were more pronounced amongst most of the tested treatments of root exudates. The most limiting combined treatment of M cognita was the mixture of C. rotundus & R officina/is root exudates. The mixtures of C. rotundus & R officina/is I or P. guajava I or M spicata root exudates gave also better results. The mean percent synergism ranged by 0.22 %to 24.0 %. Plant growth of the nematized tomato plants was insignificantly enhanced by such nematicidal root exudate mixtures.