Herbicide-resistant weeds are creating what experts are calling a “wicked problem” for South Africa’s soya bean farmers – and it’s a challenge with no quick fix in sight.
In a statement issued by Enterprises University of Pretoria, the phenomenon of herbicide-resistant weeds was described as “a vexing issue” for both producers and agrochemical companies.
“The ‘wicked’ connotation touches on an issue to which there is not a clear or easy solution,” they explain. It’s a description that resonates with many farmers who find themselves locked in an ongoing battle against weeds that simply refuse to die.
Unlike insect resistance to insecticides or human resistance to antibiotics, which have been long-standing concerns, herbicide resistance is a relatively newer headache for agriculture.
As the university points out, “herbicide-resistant weeds came to the fore relatively late, starting in the 1970s and then rapidly increasing during the 1980s and 1990s.” Even today, decades later, there is no definitive solution.
The problem stems from a familiar biological process: repeated use of the same remedy – in this case, a particular herbicide – eventually promotes resistance within the weed population.
Over time, typically within three to five years, “chemical (herbicide) selection of biotypes (individuals) occurs in populations with natural (genetic) resistance to the remedy,” Enterprises University of Pretoria explains. In simpler terms, the more farmers rely on the same chemical tools, the more they help weeds evolve to outsmart them.
The real danger, they warn, lies in continuing the practices that caused resistance in the first place. “Persisting with the practice that promoted resistance… can only worsen the situation,” they stress.
Related stories
- Farmer 101: Need help with your soybean production?
- Soybean farming the next big thing, says Grain SA
- Climate-resilient crops to consider
Understanding the mechanism of action
The development of herbicide-resistant weeds is closely tied to the mechanism of action of herbicides – in other words, how these chemicals kill or control weeds. Enterprises University of Pretoria highlights that dependence on a single herbicide mode of action is one of the main factors driving resistance.
By using the same chemical or group of chemicals year after year, producers inadvertently apply strong selection pressure. The few weeds that survive are those with a natural genetic tolerance.
These survivors then reproduce and pass on their resistant traits to future generations, leading to populations that are harder – and eventually nearly impossible – to control with traditional herbicides.
It’s a cycle that can rapidly get out of hand if not managed carefully.
No easy solutions, but some strategies
While the statement is clear that there’s currently “no solution to this problem,” it also implies that smarter, more integrated weed management practices can help slow down the spread of resistance.
This includes rotating herbicides with different modes of action, combining chemical treatments with mechanical or cultural weed control methods, and staying vigilant for early signs of resistance in the field. Innovation from agrochemical companies, while helpful, cannot replace sound farm management practices, the University suggests.
At the end of the day, herbicide-resistant weeds are not just a nuisance – they threaten the profitability and sustainability of soya bean production across the country.
And if farmers and industry players don’t act decisively, the “wicked problem” could soon become an even bigger crisis.
READ NEXT: Women in agriculture: Gender gap persists in commercial farming
Sign up for Mzansi Today: Your daily take on the news and happenings from the agriculture value chain
