Goss's wilt: a once foreign threat to maize is now local

With the emergence of Goss's wilt in certain maize-producing areas of the country, farmers are being alerted to agricultural practices and risk management procedures that may aid in the confinement of the disease.

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In 2024, South Africa’s maize production came under threat from a disease long considered foreign to its fields. Goss’s wilt, a bacterial disease caused by Clavibacter michiganensis subsp. nebraskensis, was confirmed in certain maize-producing areas of the country.

Despite this, knowledge gaps about how it acts under local conditions and the potential implication of it spreading further persist.

For this reason, an advisory note was published by the Department of Agriculture and the Agricultural Research Council (ARC) about Goss’s wilt to inform producers of the disease’s presence in South Africa, and possible agricultural practices and risk management procedures that may aid in the confinement of the disease.

A NEW REALITY

Goss's wilt was first identified in 1969 in Nebraska in the US, and remained confined to the country’s maize belt for many seasons.

However, it has since seemingly spread, with producers in North West (specifically around Parys, Carletonville, Fochville, Lichtenburg, and surrounding areas) in South Africa reporting unusual leaf lesions in maize fields during the summer production season of 2024. The lesions were briefly described as being tan, irregular, and parallel to veins with black water-soaked edges, and as showing ‘freckles’ when a light was shone from the back of the leaf. Since the disease could not be immediately identified as one of the common maize threats that typically occurs in South Africa, further investigation was necessary. The Department of Agriculture, in collaboration with the ARC, thus collected and tested samples from affected fields.