Control of nematodes

October 2000. A question was asked by Vanuatu about the most efficient way of controlling nemaodes on ginger under an organic regime, and whether Dolicus lablab is a host for nematodes.

It is difficult to find an efficient way to control nematodes that would satisfy an organic regime. Crop rotation would be the mainstay of such a system, and the components will depend on the crops that are required. Many rotations include a legume; however, Dolichos lablab (syn. Lablab niger – hyacinth bean) is a very good host for root-knot nematode, reniform nematode and lesion nematode (Pratylenchus), all of which can cause economic decline in tropical crops. There has been some work on resistant/tolerant lines of Dolichos to root knot nematode, but it was not known how reliable the resistance is.

A paper by Graham Stirling (1989) Australasian Plant Pathology 18(2) is useful in this connection as it compares sawdust and poultry manure with urea and nematicides for root-knot nematode control in ginger. Poultry manure at either 24, 36 or 48 t/ha with urea at 900 kg gave the best overall and marketable yields. Yields were similar for all levels of poultry manure; however, without the urea, yields were about 25% lower.