Nematicidal activity of aqueous and organic extracts of local plants against Meloidogyne incognita (Kofoid and White) Chitwood in Algeria under laboratory and greenhouse conditions

The nematicidal efficiency of two types of extracts (aqueous and methanolic) of 5 plants Peganum harmala L., Raphanus raphanistrum L., Taxus baccata L., Sinapis arvensis L., and Ricinus communis L. on second stage juveniles (J2s) of Meloidogyne incognita was evaluated at 4 doses in vitro (40, 50, 60 and 80%) at 4 exposure times (12, 16, 24, and 32 h). In a greenhouse, methanol extracts obtained from 0.75, 1.5, or 3 g of the dry matter of T. baccata, S. arvensis, and P. harmala were added in pots of tomato plants (Moneymaker cultivar) to test the effect of the extracts on the nematode, its reproduction, and the plant’s growth. After 32 h of exposure, the in vitro results on J2s showed that all the aqueous and methanolic extracts of the 5 plants had positive effects on J2 mortality compared to controls; water and DMSO (2%) (dimethyl sulfoxyde). In general, methanolic extracts were significantly more effective than the aqueous ones. Methanolic extracts of T. baccata, P. harmala, and S. arvensis had the highest mortality rates (100, 89.2, 86.6%), respectively, followed by the aqueous extract of T. baccata (73.8%). After 12 days, the hatching inhibition varies between (61.4%) for the aqueous extract of R. communis and (84.2%) for the methanolic extract of T. baccata. The average was significantly different from controls (DMSO 23.8 and water 21.8%) for all extracts. Methanolic extracts were not always significantly different than the aqueous ones. In vivo methanolic extracts of S. arvensis, P. harmala, and T. baccata reduced infestation than the controls. The gall index varied between 3.5 and 5.5 for the extracts than the positive control 6.5. The present study revealed the effectiveness of all tested plant extracts to root-knot nematodes without any chemical inputs.