In vivo Evaluation of Nematicidal Action of Neem Leaf and Seed Extracts on Meloidogyne incognita in Tomato and Soil pH

The present study was conducted to assess the efficacy of neem leaf extract and neem seed extract as soil amendment to control the root knot nematode Melodiodogyne incognita when used as preventive and therapeutic treatments. The virulence of pre-treated J2 with neem leaf extract and neem seed extract was also tested in vivo experiments on tomato plants in greenhouse. The effects of neem leaf extract and neem seed extract on soil pH was also determined. Non inoculated and non treated plants were used as controls. In addition, carbofuradan 3-G a chemical nematicide was used as another control. Aqueous neem leaf extract (preventive treatment) resulted in least number of galls (2.7) per root as compared to non treated plants (20.7). Post-infected treatment (therapeutic) with neem seed extract also reduced number of galls per root (7.1) but was less effective than neem leaf extract. In preventive treatments second stage juveniles in 250 g of soil were significantly reduced with neem seed extract (6.2), carbofuradan (13.3) and neem leaf extract (4.5) as compared to therapeutic treatments with neem seed extract (11.4), carbofuradan (13.6) and neem leaf extract (9.5). J2 pre-treated with neem leaf extract showed the greatest reduction in number of J2 in 250 g soil (4.5) as compared to neem seed extract (6.2) and carbofuradan 3-G (13.3). The largest number of J2 in 250 g soil was observed in carbofuradan 3-G as therapeutic treatment (13.6) and the least in neem leaf extract as preventive treatment (4.5) as compared to non treated plants (21.1). The soil treated with aqueous neem leaf extract and neem seed extract showed less fluctuation in pH as compared to non inoculated, from transplanting of seedling to harvesting time. Carbofuradan 3-G showed high fluctuation in soil pH as compared to non inoculated. Maximum shoot length (102.9cm), shoot weight (39.6 gm) was observed in neem seed extract preventive group. Neem seed extract also increased the soil pH to 9.3 and significantly reduced the number of nematodes in 250g of soil (6.27).