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EPPO quarantine pest

Data Sheets on Quarantine Pests

Xanthomonas axonopodis pv. dieffenbachiae

IDENTITY
Name: Xanthomonas axonopodis pv. dieffenbachiae (McCulloch & Pirone) Vauterin et al. Synonyms: Xanthomonas campestris pv. dieffenbachiae (McCulloch & Pirone) Dye Xanthomonas dieffenbachiae (McCulloch & Pirone) Dowson Taxonomic position: Bacteria: Gracilicutes Common names: Bacterialblight of aroids, anthurium blight, tip burn of Philodendron oxycardium (English) Dépérissement de l'anthurium (French) Notes on taxonomy and nomenclature: In a comprehensive study using DNA-DNA hybridization 20 DNA homology groups were recognized within the genus Xanthomonas. Of these, 16 were within the species X. campestris, and are now considered genomic species (Vauterin et al., 1995). Thetype species of the genus, X. campestris is emended to include pathovars only obtained from plants in the Brassicaceae. In this study a high degree of homology was detected between the species X. axonopodis pv. dieffenbachiae and a wide range of other X. campestris pathovars from nonleguminous hosts. The species X. axonopodis was emended to include these pathovars. Bayer computer code: XANTDF EPPO A1list: No. 180

HOSTS
Natural hosts are ornamental foliage plants of the family Araceae: Aglaonema commutatum, A. crispum; Anthurium andraeanum (a frequent host in USA - California, Florida, Hawaii - and in the Caribbean; Cooksey, 1985; Chase, 1987), A. crystallinum, A. scherzerianum; Caladium hortulanum, Dieffenbachia maculata (originally described on this species, but not apparently afrequent host now; Chase, 1987); Epipremnum pinnatum; Philodendron scandens subsp. oxycardium (the most frequent host in Florida, USA; Chase, 1987), P. selloum; Syngonium podophyllum (Chase et al., 1988). The tropical aroid food crops Xanthosoma caracu (Pohronezny et al., 1985) and X. sagittifolium (Berniac, 1974) are also recorded as hosts, while Colocasia esculenta has been found to be affected by aXanthomonas campestris leaf spot in Papua New Guinea (Tomlinson, 1987), which was not transmissible to Anthurium or Philodendron. Aglaonema pictum (Araceae) and Dracaena fragrans (Agavaceae) were infected on artificial inoculation.

GEOGRAPHICAL DISTRIBUTION
EPPO region: Absent (interceptions only, e.g. in the Netherlands). Asia: Philippines. Africa: South Africa.

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Xanthomonas axonopodispv. dieffenbachiae

North America: Canada (British Columbia, Ontario), Bermuda, USA (California, Florida, Hawaii, New Jersey). Central America and Caribbean: Costa Rica, Dominica, Guadeloupe, Jamaica, Martinique, Puerto Rico (Cortes-Monllor, 1992), St. Vincent and Grenadines, Trinidad and Tobago. South America: Brazil, Venezuela. Oceania: Australia, French Polynesia (Tahiti), Papua New Guinea(on taro, possibly a different pathovar; Tomlinson, 1987). Distribution map: See IMI (1996, No. 698).

BIOLOGY
The disease was first described on Dieffenbachia maculata by McCulloch & Pirone (1939). Infection and increase of the disease takes place especially under warm (>25°C) and humid conditions. The bacterium can infect through wounds, hydathodes and stomata. X. axonopodis pv. dieffenbachiaemay occur in low numbers on the leaf (epiphytically) or in the vascular system of the plant (latent infection). The bacterium can be spread by (latently) infected plants, splashing water (rain, irrigation), contaminated tools, wet clothes, infested soil and possibly nematodes during planting, leaf pruning and harvesting (Nishijima & Fujiyama, 1985). There are at least three groups of X. axonopodispv. dieffenbachiae affecting Araceae: 1) strains from Anthurium, which are more virulent on Anthurium than other strains and have a broader host range; 2) certain strains from Syngonium, serologically closely related to Anthurium strains, also virulent on Anthurium, with a narrow host range; 3) strains from other Araceae, including strains from Syngonium other than those mentioned above, which...