Why it matters (80-100 words)
Palmer amaranth is one of the world’s most aggressive and herbicide-resistant weeds and it has arrived in South Africa. First identified in the Northern Cape in 2018, this weed has since spread to Limpopo and North West, with signs of resistance to widely used herbicides like glyphosate. If left unchecked, Palmer amaranth could threaten crop production, especially in soybeans and other broadleaf crops. This project is investigating where the weed came from, how it’s spreading, and how resistance is evolving – critical information for protecting South Africa’s agricultural productivity and biosecurity.
Research approach (100 words)
To understand the spread and resistance patterns of Palmer amaranth, the project uses whole genome sequencing (WGS) of plant samples collected across South Africa and Botswana. DNA is extracted from plants and sequenced to examine genetic variation and resistance traits. The resulting data will be compared to international populations through the International Weed Genomics Consortium. This will help determine whether resistance developed before or after the weed’s arrival in South Africa, whether there were multiple introductions and how different populations are related. The findings will support the development of targeted herbicide resistance management plans and policy recommendations.
Research impact to farmers (100 words)
By identifying how and where Palmer amaranth is spreading and how resistant it has become, this project will help producers take earlier and more effective action. It will guide smarter herbicide use, delay further resistance and help shape national biosecurity strategies to limit its spread. With no new herbicide technologies on the horizon, preserving the effectiveness of existing products is crucial. This research will support practical, data-driven weed management strategies and help safeguard the long-term productivity of crops like soybean and sunflower.
Resources
Reports
Articles
PALMER AMARANTH ERADICATION PLAN
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