Preparation of a nematicidal formulation from Melia azedarach seed extract for controlling root knot nematodes (Meloidogyne incognita)

Mature seeds of Melia azedarach were harvested from north of Iran, Mazandaran province. The seeds were dried in the shade at room temperature (about 25ºC), powdered by blender. Extraction from the seeds powder was done in the Soxhlet extractor. Water soluble and Non-water-soluble components of the seed powder extract were separated by dichloromethane/water. In addition, Tween 85 was added to the extract and an 11% formulation was made from the seed extract in the laboratory. The toxicity of formulation to the root-knot nematode, Meloidogyne incognita, was studied in laboratory and pot experiments. Application rates of formulation were 0.125, 0.25, 0.5, 1, 2, 4, 8 and 16 percent for the laboratory experiment in order to determine their effects on motility and mortality of second-stage juveniles (J2) after two different exposure times (24 and 48 h). In pot experiment, 0.125, 0.25, 0.5, 1, 2 and 4 percent of the formulation were applied on nematode activity and plant growth components of tomato (Solanum lycopersicum). Neither J2 immobility nor mortality was observed in treatments with 0.125 and 0.25% doses. Exposure time was significantly (p<5%) affected J2 mortality. After 24 h, J2 mortality was 0.0, 44.30 and 76 % following treatment with 4, 8 and 16% formulation, respectively, while 100% J2 mortality was recorded for the same concentrations, after 48 h of exposure. In the pot experiment, all of the concentrations significantly reduced the numbers of galls, egg masses and eggs in tomato roots, J2s in soil and tomato roots and overall nematode population. Treatment of 4% of formulation was toxic to tomato plants and significantly reduced tomato root and stem length and fresh weights in comparison to control. Results of the laboratory experiments show good stability of the formulation. In general, 1 and 2% concentrations of the formulation controlled root knot nematode and improved tomato growth parameters under the laboratory conditions as compared with the control. Use of the recommended concentrations of this new formulation, could be a natural and eco friendly way to control root knot nematode and to reduce hazardous effects of chemical pesticides.