The threat posed by this weed compared to its indigenous relatives, is that it is resistant to at least six herbicide modes of action and cannot be controlled with, for example, glyphosate.
CropLife SA urges all crop farmers and crop advisers to expend all efforts to eradicate the Palmer amaranth and all other Amaranthus species that occur on farms. The reason for such drastic measures is that the Palmer amaranth hybridises with other Amaranth species and transfers its herbicide resistance to such hybrids. The Palmer amaranth also progressively develops resistance to herbicide modes of action that that have been used successfully thus far, and therefore leaves farmers with few options to combat the invasion. Maize farmers are at severe risk of losing their crop fields to this weed if they do not take immediate action to eradicate the weed and to prevent it from seeding. Failure to eradicate the Palmer amaranth at farm level will result in devastating weed impacts on crop production.
CropLife South Africa urgently requests that all farmers in the summer rainfall areas, especially those that grow maize, lucerne, cotton and beans do not leave any Amaranthus weeds unattended and eradicate such plants with mechanical means and the correct combination of herbicides as advised in the emergency eradication plan (https://croplife.co.za/PalmerAmaranth).
The full emergency alert which contains links to important resources is attached and can also be downloaded here.
For technical queries please contact Dr Gerhard Verdoorn at gerhard@croplife.co.za or 082 446 8946.