Burrowing nematode (Radopholus similis): a severe pathogen of ginger in Fiji

Abstract

A survey of Fijian ginger farms, and observations of rhizomes received at a processing plant in Suva, indicated that burrowing nematode (Radopholus similis) was responsible for damage to rhizomes and crop losses in two ginger-growing districts, Veikoba and Muanaweni. R. similis was isolated from both small water-soaked lesions and rotted sections of rhizomes, and a pathogenicity experiment revealed that the nematode also invaded the base of shoots, causing collapse and death of plants 20 weeks after inoculation. Symptoms were caused by the nematode alone and not by other ginger pathogens. Observations in the field and results from pot experiments suggested that it should be possible to effectively manage the nematode by rotating ginger with taro and cassava; applying large quantities of poultry manure as fertiliser; and dipping seed in hot water (51 °C for 10 min). Since the first two practices are used routinely in the Fijian ginger industry, the reason the nematode continues to cause problems is that many growers fail to ensure that the recommended hot water treatment is applied correctly.