Control of nematodes

October 2002. A question was asked by Vanuatu about the most efficient way of controlling nematodes on ginger under an organic regime, and whether Dolicus Laplap is a host for nematodes.

An efficient organic way to control nematodes is extremely difficult. Ultimately, you will have to get into a crop rotation system, and this will depend on the crops you wish to grow. 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 to 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 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.