Nematicidal potential of aqueous and ethanol extracts gained from Datura stramonium, D. innoxia and D. tatula on Meloidogyne incognita

The nematicidal effect of aqueous and ethanol extracts from leaves, roots and mixed plant parts (leaves + roots + seeds) of Datura stramonium, D. innoxia and D. tatula was evaluated for effects on second-stage juveniles (J2) and egg hatching of Meloidogyne incognita. Plant extracts were evaluated in different concentrations (6.25, 12.5, 25, 50, 100%) and exposure times of 10, 30, 60 and 120 min as well as 20 h for effects on J2 motility and egg hatch. Same extract concentrations were used to study hatch of J2 over 12 days. Furthermore, in a greenhouse experiment ethanol extracts gained from 0.75, 1.5 or 3 g of dry matter of mixed plant parts were added to 2000 ml pots with tomato cv. Moneymaker to test the effect on nematode reproduction and plant health. For in vitro tests, LC50 values ranged between 75.1 and 486.8 mg/ml for aqueous extracts and between 52.5 and 113.0 mg/ml for ethanol extracts. J2 inactivity increased with increasing exposure time and extract concentration. In general, ethanol extracts were more effective than aqueous extracts and extracts of leaves and mixed plant parts were more effective than extracts of roots. J2 exposed to the extracts for 20 h were dead, except for aqueous extracts from roots of all three Datura species and aqueous extract of mixed plant parts of D. stramonium. For all aqueous and ethanol extracts, hatching of M. incognita was lower than in the control. Percentage of non-hatched eggs was higher for ethanol extracts than for aqueous extracts, although not always significantly. In the greenhouse experiment, ethanol extracts of all three Datura species significantly reduced the nematode reproduction and gall index of M. incognita, but did not affect plant growth.