Deadly virus threatening African maize

South Africa will have to do everything possible to sharpen its biosecurity to prevent Maize Lethal Necrosis (MLN), a virus which can destroy whole maize harvests, from crossing its borders.

Addressing delegates at the annual Grain SA Congress, Dr Marinda Visser, Grain SA Manager of Research and Grain Policy, said her intention was not to talk up the dangers of MLN, but to practically address the consequences of possible invasion.

She said she can’t comment on the chances of MLN reaching South Africa, but if so, there will be serious consequences for maize farmers.

The illness was first reported in Africa in Kenya in September 2011, and has since spread to Tanzania, Uganda and South Sudan. It is believed MLN spread from China to Africa, but the illness is also found in the US and other maize producing countries.

It is a fairly new virus attacking the plant and cannot be easily treated.

“This calls for enhanced import requirements, even if other importers won’t like it. Biosecurity and the departments’ early warning system are increasingly more important. We should closely co-operate with other countries to control pests and plagues,” Dr Visser said.

She also said it is important to observe the illnesses already present in the country. MLN is a combination of two viruses: the chlorotic streak virus that occurs on maize but not in South Africa and any virus from the Potyviridae group, like the mosaic virus found on sugar cane. Dual infection from these two viruses leads to MLN.

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