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Unlocking the secrets of resistant weeds

How and why do weeds become resistant to herbicides? A new European project in which scientists from Aarhus University are participating aims to find answers to this question with the aim of developing efficient weed management strategies.

[Translate to English:] Rajgræs er en udfordrende ukrudtsplante, som er et problem for landmænd. Foto: Maurizio Sattin

In the ongoing contest between crops and weeds, some weeds are experts at staying one step ahead of the game; ryegrass is one such weed and it is widely spread in Europe despite concentrated efforts to control it. The hardy weed even has the ability to evolve multiple resistance to several classes of herbicides in the same plant. 

How does this family of grasses manage to escape the effects of herbicides? 

- Answering this question could help us gain a better understanding of the evolutionary process leading to herbicide resistance and pave the way for developing transnational management strategies that can be adapted to national conditions, says professor Per Kudsk from the Department of Agroecology at Aarhus University. He is participating in a new European project coordinated by Consiglio Nazionale delle Ricerche (CNR) in Italy that aims to reveal the secrets behind resistant weeds. 

The three-year project, entitled RELIUM, involves scientists from three different research institutions in Italy, Greece and Denmark. It has a total budget of €303,055 and has been granted €259,166 through the C-IPM second call. 

The aim of the project is to monitor and map the spread of resistance, as well as to develop innovative detection tools. It will characterise patterns, levels and resistance mechanisms of selected resistant populations of three ryegrass species and will set up resistance management strategies for perennial ryegrass in various agronomic situations. 

RELIUM is a good example of the synergy that can comes about in a European project. Each research group will contribute specific skills. At the same time, we will all benefit from having access to more extensive plant material than we would otherwise have had. Working with plants that have developed resistance under very different cultivation conditions increases the probability of finding answers to the questions that we are asking, says professor Per Kudsk. 

Understanding the evolutionary process behind resistance

There are a several ways in which weeds can evolve resistance to herbicides. The core idea of the project is to discover the underlying mechanisms that lie behind the evolution of herbicide resistance in weeds and use this information to devise effective resistance management strategies. 

The project partners will pool their resources in several ways. They will collect and share plant material and information about selected fields in which resistance has evolved. They will produce updated databases and maps of resistant perennial ryegrass in the three partner countries. The partners will then characterise the resistant populations and set up quick molecular tests for detection of target-site based and metabolic related resistance. 

Studying the selected ryegrass populations in this way will help the partners gain insight into the evolutionary process leading to herbicide-resistant populations. Finally, the partners will improve the management of resistant perennial ryegrass by developing transnational resistance management strategies adapted to national conditions. 

For more information please contact: Professor Per Kudsk, Department of Agroecology, email: per.kudsk@agro.au.dk, telephone: +45 8715 8096, mobile: +45 2228 3382 

Sustainable Pest Management is one of the research areas in which the Department of Agroecology is particularly strong and from which results are delivered in line with national and global societal challenges and goals.