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Cotton bacterial blight

Scientific Name
Xanthomonas axonopodis pv. malvacearum
Scientific Author
(Smith 1901) Vauterin et al. 1995
(Bacteria: Xanthomonadales)

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Diagnostic Images

Host Symptoms
Symptoms on capsules of Gossypium barbadense (copyright, for use contact Stephen.Allen@
Dr Stephen J. Allen CSIRO
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Diagnostic Images (29)
Diagnostic Notes

The bacteria can attack hosts during all growth stages, infecting stems, leaves, bracts and bolls. It causes seedling blight, leaf spot, blackarm (on stem and petioles) and boll rot. On cotyledons small, green, water-soaked rounded (or irregular) spots form which turn brown. Cotyledons can be distorted if the infection is intense. Black and elongated lesions can girdle the hypocotyls and kill seedlings. On the leaves, scattered small dark-green, water-soaked, areolate spots, form measuring 1-2 mm on the lower surface, which appear translucent against transmitted light. The spots increase in diameter to 5 mm, become angular, brown and later turn dark brown to blackish, becoming visible on the upper surface. On susceptible cultivars numerous spots can occur, causing chlorosis, necrosis and distortion, and eventually defoliation. When the lesions extend along the edges of the veins, the symptom is known as “vein blight”. Elongated greyish to sooty black lesions on petioles, stems and branches are called blackarm. Stems and branches girdled by lesions can break under strong winds. On bolls, small, rounded, raised, water-soaked lesions form, which later can expand to 1 cm in diameter, becoming irregular, brow to black and sunken. The lesions can become invaded by secondary micro-organisms that cause boll rot. Under favourable weather, bacterial ooze can be produced from the lesions on the lower leaf surface, on stems (gummosis) and on bolls (Patel & Kulkarni 1950, Verma 1986, Hillocks 1992, Thaxton & El-Zik 2001, Crop Protection Compendium 2005).

The Bacteria:

The morphology and cultural characteristics of X. axonopodis pv. malvacearum are described by Hayward & Waterson (1964), Verma (1986), Hillocks (1992), Supriadi et al. (1996) and Thaxton & El-Zik (2001).
More Information
Specimen Contact
Dr Jose R. Liberato
Liberato JR, Allen SJ, Suassuna ND, Mehta YR, Koenning SR & Shivas RG
22/05/2006 04:08 AEST
Last Updated
28/07/2016 09:19 AEST
Liberato JR, Allen SJ, Suassuna ND, Mehta YR, Koenning SR & Shivas RG (2006) Cotton bacterial blight (Xanthomonas axonopodis pv. malvacearum ) Updated on 7/28/2016 9:19:52 AM Available online: PaDIL -
Image Use
Free for use under the Creative Commons Attribution 3.0 Australia License