Farmer contemplating weed management in a field.

Weed Control Economics: Is the Economic Threshold Model Outdated?

Lena Kashyap in Climate & Environment August 2025 • 4 min read.

"Rethinking Strategies for Modern Weed Management"

For decades, chemical methods have dominated weed control in agriculture, leading to concerns about soil residue, water contamination, and herbicide-resistant weeds. Integrated Pest Management (IPM) emerged as a response, seeking to balance economic and ecological factors. A key component of IPM is the concept of the Economic Damage Level (EDL), which helps determine when weed control is economically justified.

The EDL, originally developed for insect pest management, was adapted for weed control in the late 1970s. This approach suggests that intervention is warranted when the cost of weed control is less than the economic damage caused by the weeds. However, adoption of EDL in weed management has been slow, highlighting a disconnect between theory and practice.

This article examines the foundations of the EDL, discusses its limitations in the context of weed management, and explores alternative approaches for making informed decisions about weed control. By understanding these limitations, we can move toward more sustainable and effective weed management strategies.

Why the Economic Threshold Model Falls Short in Weed Management

Farmer contemplating weed management in a field.

The Economic Damage Level (EDL) model aims to strike a balance between the cost of weed control and the economic losses caused by weed infestation. However, several factors limit its effectiveness in real-world weed management scenarios:

One of the primary challenges is that the EDL was initially designed for insect pests, where a clear cause-and-effect relationship exists between pest density and crop damage. Weeds, however, have a less direct impact, as their effect on crop yield depends on many interacting factors, such as the specific weed species, environmental conditions, and crop management practices.

Complex Interactions: Weed-crop interactions are influenced by various factors, including nutrient availability, water stress, and the presence of other pests or diseases.
Polyspecific Populations: The EDL model typically considers only one weed species at a time, while agricultural fields often host diverse weed communities.
Variable Biological Factors: Key variables used to determine the EDL, such as yield loss and control costs, can vary significantly across seasons and locations.
Low Competitiveness: For highly susceptible crops, the EDL may be so low that it triggers unnecessary interventions, leading to overuse of herbicides.
Long-Term Ecological Effects: Reliance on the EDL may lead to neglecting the long-term consequences of weed management practices on the soil seed bank and ecosystem health.

The limitations of the EDL model highlight the need for more comprehensive weed management strategies that consider ecological factors, weed community dynamics, and long-term sustainability.

Beyond Economic Thresholds: Embracing Holistic Weed Management

The Economic Damage Level, while a foundational concept, has limitations that hinder its practicality in modern weed management. Its reliance on simplified economic models and failure to account for complex ecological interactions often lead to suboptimal decision-making.

To move forward, researchers and practitioners are exploring alternative approaches, such as computer-based decision support systems, that integrate a wider range of variables, including weed ecology, crop physiology, and environmental factors. These tools can help farmers make more informed decisions about weed control, reducing reliance on herbicides and promoting long-term sustainability.

By embracing holistic weed management strategies that consider ecological, economic, and social factors, we can create more resilient and sustainable agricultural systems that minimize the negative impacts of weed infestations.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.5380/pes.v20i1.20476, Alternate LINK

Title: Nível De Dano Econômico Aplicado À Herbologia: Revisão

Subject: General Medicine

Journal: Pesticidas: Revista de Ecotoxicologia e Meio Ambiente

Publisher: Universidade Federal do Parana

Authors: Augusto Kalsing, Ribas Antonio Vida

Published: 2010-12-31

Everything You Need To Know

Why is the Economic Damage Level model not as effective for weed management as it is for insect pests?

The Economic Damage Level (EDL) model is limited in weed management because it was originally designed for insect pests, where there's a direct link between pest density and crop damage. Weeds, however, have a more complex and indirect impact on crop yield, influenced by factors like weed species, environmental conditions, and crop management practices. Also, the EDL model typically considers only one weed species, while agricultural fields often host diverse weed communities, making accurate assessments challenging.

How does the Economic Damage Level model fall short when dealing with multiple weed species in a field?

The Economic Damage Level (EDL) model struggles with polyspecific weed populations because it typically assesses the impact of only one weed species at a time. In reality, agricultural fields often host diverse weed communities. This makes it difficult to accurately predict the combined economic damage caused by multiple weed species competing for resources and affecting crop yield. Ignoring this complexity can lead to inaccurate intervention decisions.

Could using only the Economic Damage Level model for weed control create problems for the future?

Yes, relying solely on the Economic Damage Level (EDL) model may have long-term ecological consequences. The EDL focuses on short-term economic gains and can lead to neglecting the long-term impacts of weed management practices on the soil seed bank and overall ecosystem health. For example, overuse of herbicides, guided by the EDL, can disrupt beneficial soil organisms and promote herbicide-resistant weeds, which can cause extensive issues later.

How does the Economic Damage Level relate to Integrated Pest Management, and what are other ways to handle weeds?

While Integrated Pest Management (IPM) seeks to balance economic and ecological factors in agriculture, the Economic Damage Level (EDL) focuses on short-term economic gains. The EDL doesn't fully account for complex ecological interactions or long-term sustainability. Alternative approaches emphasize ecological factors, weed community dynamics, and the long-term consequences of weed management practices, promoting a more holistic and sustainable approach.

How do changing conditions affect the accuracy of the Economic Damage Level for weed control decisions?

The Economic Damage Level (EDL) relies on variables such as yield loss and control costs, which can vary across seasons and locations. This variability makes it challenging to establish reliable thresholds for weed control interventions. Factors like weather conditions, soil type, and crop variety influence weed-crop interactions and affect the accuracy of yield loss predictions and control cost estimations, impacting the effectiveness of the EDL model.