Comparison of the reproduction and pathogenicity of isolates of Radopholus similis (burrowing nematode) from Australia and Fiji on ginger (Zingiber officinale) and banana (Musa spp.)

Abstract

Ginger is an important commercial crop with global trade of 1.3 million tonnes, worth US$1,038 million in 2016, but is impacted by several soil borne diseases including plant-parasitic nematodes. Radopholus similis, the burrowing nematode, has been recorded as a persistent problem in Fijian ginger production, but has not been recorded on ginger in Australia. The objective of this study was to establish if differences in the pathogenicity of R. similis on ginger exist between isolates from Fiji and Australia. Four Australian and two Fijian isolates of R. similis were compared in the glasshouse for their impacts on plant growth and multiplication on ginger and banana. Harvest and plant assessments were conducted over a 10-week interval, beginning 12 weeks after inoculation. All isolates of R. similis were able to multiply on ginger, but the two Fijian isolates reduced above and below-ground ginger growth and caused significantly greater damage to rhizomes than the four Australian isolates. In contrast, the Fijian isolates did not multiply on banana or have any damaging effects, whereas, the Australian isolates multiplied and caused damage on this host. Thus, R. similis isolates from Fiji and Australia differed in pathogenicity on ginger and banana, indicating pathotype differences between isolates. Given the pathogenic variability observed in this study, care should be taken when soil and plant material (e.g. fresh rhizomes) are transferred between Fiji and Australia to avoid the potential introduction of infected material that could be used for plant propagation.