Managing herbicide resistance

Herbicide-resistant weeds are becoming a serious challenge for farmers and the agriculture sector globally. Magda du Toit asked industry experts how farmers can manage this problem.

- 

Despite all the technological advancements in agriculture, weed management remains one of the most significant challenges farmers have to cope with in crop production.

Weeds are plants that grow where they are not wanted. These unwanted plants often outcompete crops for nutrients, light, and water, and can reduce crop yields and quality.

Weeds that show resistance to herbicides present ongoing challenges to farmers and the agriculture sector globally.

According to the global Herbicide Resistance Action Committee’s (HRAC) website, hundreds of cases of herbicide resistance have been documented in more than 100 weed species around the world.

South Africa has not been spared. Herbicide resistance is becoming a critical challenge for producers, and is increasingly threatening farm productivity, says Dr Elbé Hugo, category marketing lead of herbicides at Corteva. She stressed the urgent need for integrated weed management during a recent farmer road show.

According to Hugo, herbicide resistance occurs when a weed population evolves into having the ability to survive applications of herbicides that were previously effective. “This is the result of repeated selection pressure over time. When the same mode of action is used consistently, susceptible weeds are controlled while naturally tolerant individuals survive and reproduce. Over successive seasons, these resistant individuals dominate the population, rendering certain herbicides less effective or even ineffective.”

Economically, herbicide resistance significantly impacts producers by increasing weed management costs, reducing yields, and necessitating additional herbicide applications.

Managing resistance is not just a short-term cost, but a long-term investment, says Elriza Theron, advocacy and communications manager at CropLife South Africa.