Activity of humic acid against root knot nematodes on tomato

This study was conducted to evaluate the efficiency of humic acid on root knot nematode in laboratory and under glasshouse conditions. Second stage juvenile (j2) were treated with 0.5, 1, 1.5, 2 and 2.5 ml of concentrated humic acid in petriplares. The soil around tomato plants in pots was treated with same above concentrations in glasshouse. Results showed that humic acid had significant lethal effect on j2 in laboratory test that increased with humic acid concentration. The highest effect 185.0 was obtained with 2.5 ml of concentrations humic acid compared with 35.0 in control. The application of humic acid in the soil around tomato plant root previously inoculated with root knot nematodes reduced significant the number of galls on the root and root galls index compared with untreated control plants. The lowest root gall index 1 was found on plant roots treated with 2.5 ml of concentrated humic acid compared with 4.6 in control. The reduction of galls was found associated with improvement of plant growth parameters. The highest increases in fresh and dry weights were manifested with 2.5 ml of humic acid that attained to 6.9 and 1.30 g. for shoot, 3.43 and 1.9 g. for root respectively compared with 3.6 and 0.603 g. for shoot, 1.33 and 0.52 g. for root respectively in control. The results suggest that soil treatment with humic acid offers significant nematode control and improves plant growth.