Crop rotation, organic amendments and nematicides for control of root-knot nematodes (Meloidogyne incognita) on ginger

Abstract

Two field experiments were carried out in a clay-loam soil to determine whether damage caused by root-knot nematode on ginger could be reduced by crop rotation and organic amendments, rather than with nematicides. When early-harvest ginger was grown for three successive years, root-knot nematode populations remained low and caused no damage in the first crop, which followed two years of green panic (Panicum maximum). Nematode damage was observed in the second and third crop, but the severity of symptoms on rhizomes was reduced by amendments containing poultry manure and/or sawdust. However, the best control was achieved with a nematicide program involving pre-plant fumigation with ethylene dibromide and post-plant sprays of fenamiphos. In a second experiment, late-harvest ginger was grown every second year, with a green manure crop in the intervening year. Populations of root-knot nematode were lower following forage sorghum (Sorghum bicolor × sudanense) cv. Jumbo than following lablab (Lablab purpureus) cv. Highworth. However, when ginger followed either crop and amendments of poultry manure and/or sawdust were also applied, nematode damage was negligible. These results suggest that rootknot nematode on ginger can be controlled by alternating ginger with a green manure crop and applying at least 150 m³/ha/annum of poultry manure, with or without additional sawdust. When ginger is grown in successive years, nematode populations increase to high densities despite the use of organic amendments, so that nematicides are needed to achieve satisfactory control.