How South Africa is keeping invasive famine weed at bay

The poisonous herb, Parthenium hysterophorus, is one of the world's most destructive invasive plants. It threatens biodiversity, national food security and human health. Native to parts of Central and South America (Gulf of Mexico) it has spread to more than 40 countries including Australia, India, Pakistan, Ethiopia, Swaziland and South Africa. In South Africa it's known as famine weed.