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  • Writer's pictureEric McQuiston, PLA

The Great Round-Up Debate: Navigating Glyphosate's Role in the Landscape

– A Landscape Architect's Perspective


As landscape architects, we hold a profound responsibility for shaping outdoor spaces that harmonize with nature, elevate human experience, and foster sustainable ecosystems. Amidst this endeavor, the use of glyphosate, a widely-debated herbicide, has emerged as a contentious topic. In this article, we will delve into the pros and cons of glyphosate use in the landscape, grounded in a historical and current context. By examining scientific studies on its safety and efficacy, we can navigate the complexities of the "Great Round-Up Debate" from the perspective of landscape architecture.


 

A Brief History of Glyphosate

Glyphosate, the active ingredient in the well-known herbicide Roundup, was discovered in 1970 by chemist John E. Franz who uncovered its herbicidal properties1. Its introduction in the mid-1970s marked a significant milestone in weed control. Glyphosate's mode of action disrupts the shikimic acid pathway in plants, effectively inhibiting their growth. The herbicide's efficiency and broad-spectrum weed control capabilities led to its rapid adoption in agriculture and beyond.


Historical and Current Use

While initially embraced by farmers for its effectiveness in managing weeds in crops, glyphosate's utility extended beyond agriculture. The horticultural sector, including landscaping and residential gardening, recognized its value in controlling unwanted vegetation. Moreover, genetically modified (GM) crops engineered to withstand glyphosate, commonly referred to as "Roundup Ready" crops, expanded the herbicide's applications.

For landscape architects, glyphosate appeared to offer an appealing solution to weed management challenges. It promised precise control of invasive plants, simplified site preparation for new plantings, and efficient maintenance of cultivated landscapes. The convenience of glyphosate aligned with the demands of creating visually appealing and functional outdoor spaces.



 

The Pros of Glyphosate Use


Precision in Weed Management

From a landscape architect's standpoint, glyphosate's precision in targeting specific plants can be a valuable tool. Invasive plant species can pose a threat to the ecological integrity of landscapes by outcompeting native species. Glyphosate's targeted approach can aid in restoring balance to ecosystems and promoting the growth of desirable vegetation.

Erosion Control and Site Preparation

Glyphosate's role in preparing sites for planting can contribute to erosion control and soil conservation. By minimizing the need for mechanical site preparation, the herbicide can help prevent soil disturbance and degradation. This is particularly advantageous in projects where preserving soil structure and minimizing erosion are priorities.

Efficient Landscape Maintenance

For landscape architects tasked with maintaining existing landscapes, glyphosate can offer efficiency. It allows for the management of unwanted vegetation in a timely manner, reducing the need for labor-intensive manual weeding. This efficiency can translate into cost savings for clients while preserving the overall aesthetics of the landscape.


The Cons of Glyphosate Use

Ecological Implications

A significant concern from a landscape architect's perspective is the potential impact of glyphosate on non-target species and ecosystems. While glyphosate's specificity is an advantage, unintended consequences can arise. The elimination of non-invasive plants could disrupt food chains and habitat dynamics, affecting the overall health of ecosystems.

Soil Health and Microbial Diversity

Landscape architects emphasize the importance of healthy soils for plant growth and ecosystem vitality. Glyphosate's potential impact on soil health and microbial diversity raises questions about its compatibility with long-term sustainability goals. Alterations to soil structure and microbial communities can have cascading effects on nutrient cycling and plant health.

Public Perception and Aesthetics

As stewards of the landscape, landscape architects must consider public perception and aesthetic concerns. Glyphosate's association with health and environmental controversies can influence public sentiment. Moreover, the potential browning and discoloration of treated plants can detract from the visual appeal of landscapes.

 

The Science


Understanding Safety: The LD50 Comparison

A metric commonly employed to gauge toxicity is the LD50 (lethal dose for 50% of a population). In the case of glyphosate, its LD50 is relatively high, indicating low acute toxicity (i.e. the higher the score, the lower the toxicity). To contextualize this, consider that the LD50 of table salt is lower than that of glyphosate2. It's intriguing to note that other commonplace household items such as aspirin and caffeine possess lower LD50 values than glyphosate3 (thus making them more toxic as measured by LD50 metrics than glyphosate). This comparison serves to underscore that while glyphosate's safety profile raises concerns, its toxicity is not exceptional when juxtaposed with substances commonly found within households.



Evaluating Carcinogenic Potential: Glyphosate and Real-World Exposure

The International Agency for Research on Cancer (IARC) classified glyphosate as a "probable human carcinogen"4, igniting global concerns (and lawsuits). However, regulatory bodies like the U.S. Environmental Protection Agency (EPA) and the European Food Safety Authority (EFSA) contend that glyphosate, when used as directed, poses no unreasonable risks5. To contextualize the potential carcinogenicity, let's consider the amount of glyphosate exposure required to be considered carcinogenic.


The IARC classification is based on studies demonstrating increased cancer risks in laboratory animals exposed to high levels of glyphosate. To replicate these levels in humans, a substantial amount of glyphosate would be required – an amount significantly beyond typical real-world exposure. For instance, a study conducted by the Environmental Protection Agency (EPA)6 estimated that the maximum potential human exposure to glyphosate from food residues is approximately 1,000 times lower than the level that might cause any adverse effects.


Consider an analogy: Consuming large quantities of table salt can lead to adverse health effects. However, this does not imply that the customary use of salt for seasoning food is dangerous. Similarly, while the potential carcinogenicity of glyphosate is a topic of discussion, it is crucial to distinguish between laboratory exposure levels and the real-world exposure experienced by the general population.


As landscape architects, we must engage in meticulous appraisal of the quality and scope of scientific studies. A comprehensive understanding of the scientific landscape empowers informed decision-making that respects both environmental health and human well-being.


 

Balancing Act: Landscape Architects' Approach

Navigating the glyphosate debate requires landscape architects to adopt a balanced and thoughtful approach. Here are a few principles to consider:


1. Site-Specific Analysis

Each landscape project is unique. Conduct thorough site analyses to understand the ecological context, existing vegetation, and potential weed challenges. This knowledge will inform the decision-making process regarding glyphosate use.


2. Integrated Weed Management

Prioritize integrated weed management strategies that emphasize preventive measures, cultural practices, and alternative methods before resorting to chemical solutions. Integrated approaches align with landscape architecture's commitment to sustainability.


3. Communication and Transparency

Engage in transparent communication with clients, stakeholders, and the public about weed management practices. Educate clients about the benefits and potential drawbacks of glyphosate use and explore alternative approaches based on project goals.


 

Conclusion

The "Great Round-Up Debate" demands that landscape architects adopt a nuanced perspective that balances design aspirations with ecological stewardship. Glyphosate's merits – from precision weed control to efficient maintenance – must be weighed against its drawbacks, encompassing potential ecological disruptions and public perception concerns.


As landscape architects, we navigate this intricate terrain armed with an unwavering dedication to well-informed decision-making and a deep appreciation for the intricate interplay that defines our natural world. Through dialogue, introspection, and a commitment to adaptive practices, we endeavor to create landscapes that are not only visually captivating but also resilient and sustainable – landscapes that honor the intricate dance between humanity and nature.


Footnotes:

1. Duke, S. O. (2018). Glyphosate: A once-in-a-century herbicide. Pest Management Science, 74(11), 2205-2211.

2. Sneddon, J. (2016). Lethal doses. ChemMatters, 34(5), 6-7.

3. Ibid.

4. IARC. (2015). IARC Monographs Volume 112: Evaluation of Five Organophosphate Insecticides and Herbicides. International Agency for Research on Cancer.

5. EPA. (2020). Glyphosate. United States Environmental Protection Agency.

6. EPA. (1993). Glyphosate Reregistration Eligibility Decision (RED). United States Environmental Protection Agency.



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