Effect of leaf and root extracts of Phytolacca americana L. on hatching of Globodera rostochiensis and Meloidogyne artiellia

Abstract

An investigation was conducted to assess the hatching response of Italian populations of the potato cyst nematode, Globodera rostochiensis, and the British root-knot nematode, Meloidogyne artiellia, to pokeweed (Phytolacca americana) leaf and root extracts under laboratory conditions at 20 ± 1 °C. Cysts of G. rostochiensis were exposed to a series of increasing pokeweed leaf or root extract aliquots (0.25, 0.5, 0.75 or 1 ml), which were added to 3 ml of a 0.6 mM sodium metavanadate (NaVO3) solution. Egg masses of M. artiellia were exposed to the same rates of leaf and root extracts but the extracts were, instead, added to 3 ml of distilled water. Controls were NaVO3 0.6 mM and both extracts alone for G. rostochiensis and distilled water for M. artiellia experiments. No egg hatched from cysts of G. rostochiensis incubated in pokeweed leaf or root extract alone, but 47% hatched from cysts in NaVO3 alone in 7 weeks. Hatch of G. rostochiensis was greatly stimulated by incubation in NaVO3 with the addition of 0.25 ml of leaf or root extract, reaching 79.5% and 68.2%, respectively. Egg hatch increased further in NaVO3 plus 0.5, 0.75 and 1 ml of pokeweed leaf or root extract, and reached cumulative hatches of 86-90.5% of eggs from cysts. Egg hatch of M. artiellia was 76.5% in distilled water alone; it was not affected by extracts of pokeweed leaf at 0.25 and 0.5 ml or by extracts of pokeweed root at 0.25 ml, but was significantly suppressed at larger concentrations of both extracts.