Weed resistance screening and management

The spread of herbicide-resistant weeds poses a significant challenge to farmers worldwide. Recognizing the early signs of herbicide resistance and implementing proactive measures is crucial for preserving crop yields and ensuring the sustainability of agricultural systems. Here are some tips to ensure that you and your farm can mitigate the risks of herbicide resistance. 

The growing issue of herbicide resistance

Herbicide resistance has become increasingly prevalent in agriculture across the world with Canada currently ranking 3rd for resistant weeds behind Australia and the US.

Repeated use of the same herbicides has exerted selective pressure on weed populations, driving the evolution of resistant biotypes. As a result, herbicide-resistant weeds pose a threat to crop productivity, leading to yield losses and escalating production costs.

Recognize the early signs of herbicide resistance in the field

Early detection of herbicide resistance is needed for effective weed management. Observe changes in weed populations, such as reduced herbicide efficacy or shifts in weed populations. Herbicide resistance screening tests can provide valuable insights into the presence and extent of resistance within weed populations. If resistant biotypes can be detected early, proactive measures can be taken to prevent the further spread of resistant weeds in fields.

herbicide resistance

Early detection is crucial

Early detection through herbicide resistance screening enables growers to make informed and effective decisions about weed management strategies. Farmers can tailor herbicide applications, avoiding ineffective treatments and minimizing the risk of further resistance development by accurately identifying resistant weed populations. Moreover, early detection allows for timely implementation of diverse weed management tactics, such as crop rotation, herbicide rotation, and/or mechanical weed control methods, all with the goal of reducing herbicide-resistant weed seeds being set in fields.

Early detection of herbicide resistance helps farmers maximize the efficiency of weed management practices by avoiding ineffective herbicide applications. Preventing yield losses due to herbicide-resistant weeds helps preserves crop yields, enhance profitability and expedite the adoption of alternative weed management strategies, ensuring sustainable crop production and long-term viability.

Use screening results to choose effective weed management strategies

Herbicide resistance screening results serve as invaluable tools for guiding weed management decisions. Armed with knowledge of resistant weed populations, farmers can deploy targeted herbicide treatments, selecting herbicides with different modes of action to combat resistant biotypes effectively. Screening results inform the best use of herbicide layering, crop rotations, and integrated weed management strategies.

• Herbicide layering: Herbicide layering involves applying herbicides with multiple modes of action that are effective on the known weed populations. There are many broadleaf herbicides in Canada different modes of action that can be applied sequentially or simultaneously to control weeds while minimizing the risk of resistance development. This approach slows the development of resistance to any single herbicide. Farmers can slow down the development of herbicide-resistant weed populations over time by diversifying herbicides and rotating modes of action.

• Crop Rotations: Rotating crops can help break pest and weed cycles, as different crops may be less susceptible to certain pests or may have different nutrient requirements, reducing pressure on the soil and minimizing the buildup of pests and weeds. Another reason crop rotation is effective is that herbicides differ across crop groups, therefore rotating crops also helps with rotating modes of action over multiple years. Preventing the use of the same active ingredients year after year.

• Integrated Weed Management (IWM) Strategies: Integrated Weed Management is an approach that combines multiple strategies to control pests. Screening results inform the selection and timing of weed management tactics within an IWM program. IWM techniques such as crop rotation, cover cropping, and intercropping disrupt weed growth cycles and create unfavourable conditions for weed establishment. Mechanical methods, such as hand-weeding, mowing, and cultivation, physically removing weeds from fields, reducing weed competition with crops and preventing seed production can all help to control pests. Integrated use of herbicides with different modes of action ensures comprehensive weed control while mitigating the risk of herbicide resistance.