Jordi Recasens, head of the weed science and plant ecology research group at UdL-Agrotecnio, has warned that excessive use of herbicides creates resistant weeds. Speaking in Lleida, Recasens highlighted the growing problem of herbicide resistance, which has increased significantly due to over-reliance on chemical control methods.
His research group recently received the City of Lleida Award, recognising 40 years of work in the field. Recasens, who started his research in 1983, explained that the group's long history has seen them become a key resource for agricultural businesses in Catalonia and beyond.
Recasens noted that funding for research has improved over the past four decades, with more calls for proposals from the Generalitat and the Spanish Ministry of Education. Many of these now include a knowledge transfer component, allowing private entities to contract research groups to solve specific problems. This approach helps researchers interact directly with companies.
Addressing Precarious Employment in Research
Despite improved funding, Recasens pointed out ongoing issues with job precarity for researchers. He mentioned that before the pandemic, his group had two doctors whose salaries came from projects and agreements, not directly from the university. Now, one has secured a stable position at 49 years old, another at 47, and a third at 45. Recasens believes this delay in stabilisation for researchers who enjoy academia and research indicates a systemic problem.
While there is more funding and minimum research and teaching standards are now comparable to the European average, salaries and resources in Spain remain lower, according to Recasens. He also highlighted the increasing collaboration with businesses, stating that his group has signed agreements with many companies who now actively seek their advice on crop management.
The Impact of Weeds and Herbicide Resistance
Recasens explained that weeds are often misunderstood. Spain uses €450 million worth of herbicides annually, Europe €15 billion, and the world nearly €70 billion. This shows a huge dependence on chemical control, which Recasens described as very effective. He noted that uncontrolled weeds in a maize or cereal field can reduce yields by 35%.
His group studies weeds to optimise control methods. Recasens compared repeated herbicide application to a person constantly taking the same antibiotic, which can lead to resistance. A genetic mutation in a plant can make it resistant to an herbicide, passing this trait to its offspring. This process is increasing, driven by excessive herbicide use and a dependence on chemical-only control.
When resistance problems arise, farmers must change their approach. Recasens teaches integrated management in the plant health master's programme, advocating for not relying on a single method. This could involve applying herbicide one year and changing the crop the next, or using mechanical methods like ploughing fallow fields.
The Globalisation of Weeds and Glyphosate Debate
Weeds are also globalising, arriving from various regions. Recasens cited Amaranthus palmeri, which came to Lleida and Aragon 8 to 10 years ago from the United States via grain used for feed. This weed, with resistant genes, can grow up to 2 centimetres per day, with female plants producing between 500,000 and 800,000 seeds. For such weeds, chemical methods are still necessary, but they must use herbicides to which the weed is not resistant. Researchers are testing different active ingredients and mixtures, with some promising results, but Recasens warned against calling any single solution definitive due to the weed's rapid reproduction and potential for new resistances. Crop rotation is another useful strategy.
Regarding glyphosate, Recasens acknowledged its effectiveness. For non-organic fruit and vine growers, or those using direct sowing for winter cereals who need to eliminate weeds beforehand, glyphosate is a good option. However, repeated use can lead to resistance. He believes the herbicide has a poor reputation partly due to its historical manufacturer, Monsanto, now owned by Bayer.
While debates have occurred about its toxic effects on humans, these have not been proven, according to Recasens. He noted its environmental impact, as it eliminates weeds, insects, and other organisms in the ecosystem. From an agronomic perspective, however, Recasens questioned how direct cereal sowing, which accounts for over 60% in areas like Segarra, Urgell, and Noguera, could be done without glyphosate. He stressed it is a useful tool that needs to be used correctly.
During the EU debate on glyphosate, the European Weed Research Society asked his research centres to participate. The consensus among researchers was that banning it could create significant problems for many producers. Recasens concluded that while it is not a miracle solution, it is useful, and finding a balance in its use is key.
