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November 14th, 2017 / Farmers' Weekly, South Africa

Outbreaks of a previously unknown wheat leaf disease have been reported in South Africa, which could have a serious impact on food security and sustainable wheat production in the country.

The disease involved severe discolouration of wheat leaves and, according to Dr Tarekegn Terefe, senior researcher at ARC-Small Grain in Bethlehem, had become widespread in the irrigation wheat-growing areas of South Africa.

He said the disease usually started to become evident as yellow streaks parallel to leaf veins, and gradually join, turning the infected leaves yellow.

In most cases, infected plants were shorter than normal.

Signs of the disease had been observed at tillering and at later growth stages. The outbreaks usually occurred in patches.

“This expanding disease could eventually lead to [a wider] disease outbreak and yield losses, threatening the wheat industry and local food security. It is important that we identify the specific cause/s of the disease in order to formulate relevant control measures,” Terefe said.

This disease was first observed in 2011 in some fields in Winterton and Bergville in KwaZulu-Natal and in Kimberley in the Northern Cape.

Since then, it has been detected in sporadic patches in Harrismith and Clocolan in the Free State; Brits in the North West; and Koedoeskop in Limpopo.

Indications were that the disease was caused by viruses. However, the symptoms were not consistent with previously reported wheat viruses in South Africa, such as Barley yellow dwarf virus, maize streak virus and Brome mosaic virus. Read more