Resistance of Vetiver Grass To Infection By Root-Knot Nematodes (Meloidogyne Spp)
Lynette West1, Graham Stirling 1, Paul Truong2

1Plant Protection Unit, Queensland Department of Primary Industries, 80 Meiers Road,
Indooroopilly, Queensland 4068
2 Resource Management Institute, Queensland Department of Primary Industries, 80 Meiers Road, Indooroopilly, Queensland 4068

Introduction

Vetiver grass (Vetiveria zizanioides) is well known for its tolerance to adverse soil conditions and is used as a contour hedge to prevent soil erosion on steep slopes in some countries. Anecdotal evidence also indicates that when grown adjacent to orchard trees for soil and water conservation purposes, Vetiver appears to improve tree growth.

In Queensland, Vetiver grass is being used to stabilize soil on slopes in sugarcane and pineapple plantations. Since root-knot nematodes (Meloidogyne spp.) can be a problem on both crops (Spaull & Cadet 1990, Caswell et all 1990), the status of Vetiver as a host of root-knot nematode was of interest. This work aimed to answer that question.

Materials and Methods

Two Vetiver varieties were screened for resistance against five root-knot nematode populations. The populations are representative of the main genetic groups of Meloidogyne in Australia and consist of four species (viz. M. arenaria, M. incognita [populations B 1 and B2], M. javanica and M. hapla). They were identified using DNA technology (Hugall et al 1994). The two Vetiver varieties used were Monto, a sterile selection, and a non-sterile type from Western Australia. The test plants were grown in the glasshouse in 200 mm pots in a sterile sand mix. Once they were established, five replicate plants were inoculated with 10,000 root-knot nematode eggs. A susceptible tomato cultivar (cv. Tiny Tim) was used as a standard for comparative purposes. Plants were harvested 6 weeks after inoculation, when egg masses on tomatoes were mature. Roots washed free of soil were immersed in a 1% NaOCl solution for three minutes and eggs were collected on a 38Ám sieve and counted.

Results and Discussion

Both Vetiver varieties were highly resistant to all five root-knot nematode populations.
Reproduction was approximately 1000-fold less than on the susceptible tomato. Vetiver also compared favorably with other grasses that have been found to be resistant to
root-knot nematode in similar tests. Our results confirmed those of de Moura et al
(1990) who found that Vetiver was "immune" to both M. incognita race 1 and M. javanica.

Conclusion

Since the grass was resistant to all major species of Meloidogyne, Vetiver is unlikely to exacerbate problems caused by root-knot nematodes when used as a cover, companion or hedgerow crop.