Australasian Plant Pathology, 2001, 30, 283–284

DISEASE NOTES OR NEW RECORDS J. W. Marshall et al.

First record of Meloidogyne fallax in New Zealand

AP01033

J. W. MarshallA, C. ZijstraB and K. W. L. KnightC A

New Zealand Institute for Crop and Food Research, Private Bag 4704, Christchurch, New Zealand. Plant Research International, Wageningen, The Netherlands. C National Plant Pest Reference Laboratory, MAF, PO Box 24, Lincoln, New Zealand. A Corresponding author; email: [email protected] B

Abstract. Meloidogyne fallax (Karssen, 1996) was identified from specimens of potato tubers and soil from potato-producing land, and roots and soil from infected cotula (Lepinella spp.) bowling greens. M. fallax was suspected from morphological characteristics and low temperature tolerance. This was confirmed by testing with a polymerase chain reaction-based assay capable of discriminating M. hapla, M. incognita, M. javanica, M. fallax and M. chitwoodi. Meloidogyne chitwoodi was not detected. In 1998, an increasing number of atypical Meloidogyne samples was being submitted to the National Plant Pest Reference Laboratory (Lincoln, New Zealand, formerly the Plant Protection Centre). In autumn of the same year, a sample of potato (Solanum tuberosum L. cv. Russet Burbank) tubers was found to be heavily infected with root knot nematodes. The symptoms were unusual in that the developing females and their egg masses were deeply embedded (some more than 10 mm) in the tubers, and the surrounding tissues were brown and suberised. These nematodes were tentatively identified from hatched juveniles as having characteristics of M. incognita (Kofold & White, 1919) Chitwood, 1949. However, the cool temperatures of the growing site made this diagnosis unlikely. Most of the diagnostic features of the second stage juveniles of M. fallax Karssen, 1996 are within the extreme range of those for M. incognita. In 1999, 29 isolates of root knot nematodes from potato, kiwifruit (Actinidia deliciosa (A. Chev.) Liang & A.R. Fergusson), cotula (Lepinella Cass. spp.), persimmon (Diospyros kaki L.f.), avocado (Persea americana Mill.), tamarillo (Cyphomandra betacea (Cav.) Sendtner), passionfruit (Passiflora edulis Sims.), wheat (Triticum aestivum L.) and carrots (Daucus carota L. var. sativa) were collected from the following Crosby (Crosby et al. 1976) districts: ND, WO, BP, TK, WI, WN, NN, MC, SC and SL. The root knot nematode material used in the following experiments was either individual females and their egg masses hand picked from the root tissue and/or larvae extracted from the soil using a modified Whitehead tray technique (Whitehead and Hemming 1965). Reference samples of M. trifoliophila Bernard & Eisenback, 1997 were supplied by C. Mercer (AgResearch, Palmerston North). All nematodes were identified to species from morphological characters described by Jepson (1987) and Karssen (1996), and comparisons with NPPRL reference material. © Australasian Plant Pathology Society 2001

The nematodes were processed to extract DNA that was subjected to polymerase chain reaction (PCR) differentiation using published protocols (Zijlstra et al. 1997). The Plant Research International (The Netherlands) (PRI) proprietary primer sets were supplied by Dr Zijlstra during a visit to New Zealand. These primers are specific to detect and differentiate M. hapla Chitwood, 1949, M. fallax, M. chitwoodi Golden, O'Bannon, Santo & Finley, 1980, M. incognita, M. javanica (Treub, 1885) Chitwood, 1949 and M. arenaria (Neal, 1889) Chitwood, 1949. Reference DNA from each species was included as positive controls in all PCR reactions. This small scale study showed that, of the 29 Meloidogyne isolates tested, 22 were positive for M. hapla and 6 were positive for M. fallax. There was a mixed population of M. hapla and M. fallax in five isolates. Four isolates failed to produce useful DNA. The remaining two isolates produced a non-specific band of around 1000 base pairs. Morphologically, at least, one of these nematode isolates resembled M. naasi Franklin, 1965. These were included in the test to confirm the species specificity of the PRI primer set. The positive incidences of M. fallax were from potato tubers and soil from potato-producing land, and roots and soil from infected cotula bowling greens from both the North and South Islands. Subsequent to this study, additional M. fallax samples have been identified by morphological characteristics and confirmed by PCR. These were all from potato tubers. As a result of these findings we are planning a more comprehensive survey to determine the incidence of M. fallax in New Zealand potato-growing areas. We will also be developing species-specific primers for M. trifoliophila and M. naasi. Specimens of the M. fallax populations used in these tests are deposited in the National Plant Pest Reference Laboratory, Lincoln.

10.1071/AP01033

0815-3191/01/030283

284

J. W. Marshall et al.

References Crosby TK, Dugdale JS, Watt JC (1976) Recording specimen localities in New Zealand: an arbitrary system of areas and codes defined. New Zealand Journal of Zoology 3, 69. Jepson SB (1987) ‘Identification of root knot nematodes (Meloidogyne species).’ (CAB International: Wallingford, UK) Karssen G (1996) Description of Meloidogyne fallax n. sp. (Nematoda: Heteroderidae), a root knot nematode from The Netherlands. Fundamental and Applied Nematology 19, 593–599.

Whitehead AG, Hemming JR (1965) A comparison of some quantitative methods of extracting some small vermiform nematodes from soil. Annals of Applied Biology 55, 25–38. Zijlstra C (1997) A fast PCR assay to identify Meloidogyne hapla, M. chitwoodi, and M. fallax, and to sensitively differentiate them from each other and from M. incognita in mixtures. Fundamental and Applied Nematology 20, 505–511.

Accepted 13 April 2001

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