Effect of chestnut tannins on the root-knot nematode Meloidogyne javanica

Among the natural products extracted from plants, tannins have been reported to possess antihelmintic properties especially for gastrointestinal nematodes in ruminants. Also, they are toxic to a wide range of fungi, bacteria and yeasts. Therefore, an in vitro and a glasshouse pot experiments were undertaken to evaluate the effect of chestnut tannins on the control of the root-knot nematode Meloidogyne javanica. In the in vitro experiment, different tannin concentrations in a geometric scale (from 0.32 to 20.48 g/l), were tested for their effect on hatching of the nematode, whereas in the pot experiment, 100, 250 and 450 g/m2 of tannins in aqueous solutions, were used in pots at transplant or at transplant and two weeks later for their effect on nematode control. In both experiments treatments were compared to untreated and fenamiphos-treated controls. In vitro a nematostatic effect of tannins was observed, whereas in the pot experiment a significant reduction of eggs and juveniles/g root, total population density and reproduction rates of the nematode were recorded. The anatomical changes induced by M. javanica in tomato roots treated with tannins did not differ from those produced by this and other Meloidogyne species on various hosts reported earlier.