Three experiments were conducted to control the root-knot nematode; Meloidogyne javanica infecting peanut by using non chemical control viz certain bioagents, plant extracts and algae under laboratory, greenhouse and field conditions in Egypt. Seven treatments including suspension of orange oil, Bacillus thuringiensis, Trichoderma harzianum, Spirulina platensis, Gomphrena globosa, Origanum majorana and Mocap were used.
Laboratory experiment revealed that high percentage of juvenile mortality occurred during all the exposure periods of all treatments especially after 72 hrs Data also showed that the treatments of both orange oil and Spirulina platensis had a significant effect on juvenile mortality especially at the highest concentration (86.6% and 78.4%) respectively. While, Origanum majorana showed the lowest effect at the highest concentration (64.8%).
Under greenhouse conditions all treatments led to increase the total fresh weight of shoots and roots of peanut plants especially at the highest concentration. The treatment of orange oil revealed the highest value of percentage increase of the whole plant fresh weight at the highest concentration (78.5%) but lower than Mocap treatment (86.3%), while the treatment of Origanum majorana gave the lowest value of percentage increase of the whole plant fresh weight at the lowest concentration (56.5%).
Under field conditions all treatments increased the crop weight of peanut. The treatment of orange oil showed the highest increase in the weight of 100 seeds of peanut (81.93 g) but lower than Mocap treatment (82.56 g). While the treatment of O. majorana showed the lowest effect (73.23 g) compared to control (55.23 g). T. harzianum, B. thuringiensis and G. globosa occupied an intermediate position. On the other hand, other parameters including plant height, numbers of branches and pods as well as pods weight/plant gave the same trend. Orange oil and Spirulina platensis were the most effective treatments in reducing numbers of developmental stages, egg laying females, number of eggs/egg-mass and number of second stage juveniles but lower than Mocap treatment, whereas treatment of O. majorana was the least effective one under both greenhouse and field conditions.