Sustainability Needs More Than a Label
‘Sustainability’ is a buzzword at the moment, but it can be thrown around like popcorn at the movies. These kernels of information are valuable to consumers, yet they continue to fall through the cracks of our understanding.
I want to get serious and clear about certain practices in the wine industry—particularly weed control. These practices may be common knowledge among grape growers, but they are not always understood by the people purchasing and drinking the wine.
True sustainability should encompass environmental protection, social responsibility, economic viability and the production of high-quality wine. In my view, the routine use of herbicides holds viticulture back from achieving genuine sustainability.
What Herbicide Use Looks Like in a Vineyard
At the height of spring growth, it is often easy to distinguish vineyards that use herbicides from those that do not. The giveaway is the pale yellow or bare strip of ground running beneath the vines like a runway.
Not all vineyards use herbicides, and there is a growing movement towards farming with fewer chemical inputs. However, resistance to change remains firmly embedded in conventional agriculture and, in many cases, it comes down to time and money.
Why Herbicides Remain Common
Mulching beneath the vines can be extremely effective, but someone must grow or source the material, cut it, bale it, transport it and undertake the labour-intensive work of laying it along the rows.
Undervine weeding machinery can also be effective, but it is expensive to purchase, operate and maintain. Sheep can graze a vineyard during winter, but they require fencing, feed, veterinary care, labour and sufficient land for appropriate rotation.
The Australian Wine Research Institute identifies cultivation, mowing, sweeping, straw mulch, sheep grazing and undervine cover crops among the non-chemical options available to grape growers. Each method has advantages and limitations, depending on factors such as soil type, slope, rainfall, vine age, weed pressure and available machinery. There is no single solution suitable for every vineyard.
For many growers, spraying herbicide remains faster, easier and less expensive in the short term.
The more important question is whether short-term convenience provides a complete and honest measure of its cost.
Understanding Glyphosate
Glyphosate is a broad-spectrum, non-selective systemic herbicide used to control actively growing plants. It works by inhibiting an enzyme within the shikimate pathway, which plants and many microorganisms use to produce essential aromatic amino acids. Animals do not possess this metabolic pathway.
That distinction matters. It would not be scientifically accurate to suggest that glyphosate must affect humans simply because human, animal and plant DNA share the same four basic chemical building blocks.
The legitimate questions surrounding glyphosate instead concern the amount and frequency of exposure, the complete formulations in which it is used, its possible effects on non-target organisms and microbial communities, and the quality of the evidence relating to long-term human and environmental health.
Why Does the Grapevine Not Die?
People sometimes ask why the grapevine itself does not die when glyphosate is sprayed beneath it.
Glyphosate is absorbed primarily through green, actively growing plant tissue. In established vineyards, it is generally applied as a directed spray beneath the vines while avoiding leaves, shoots, suckers and other green parts of the grapevine.
Applications may also be timed for periods when the vines are dormant and the trunks are covered in mature bark. This reduces the likelihood of the chemical being absorbed by the vine.
Accidental contact with active green tissue can still cause stunting, distorted growth, dieback or more substantial injury. Product restrictions therefore apply around young vines, and shielding may be required to prevent spray or drift from reaching susceptible tissue.
The grapevine survives not because glyphosate is incapable of affecting it, but because the application is intended to target the vegetation growing beneath it.
What Happens in the Soil?
Glyphosate usually binds strongly to soil particles, which limits its immediate availability and generally reduces movement through the soil profile. It is broken down largely through microbial activity, with aminomethylphosphonic acid, or AMPA, formed as its principal degradation product.
Its persistence varies considerably according to soil composition, moisture, temperature, microbial activity, application history and the way water moves through the soil. Research suggests glyphosate itself may dissipate relatively quickly under some conditions, while AMPA can be more persistent. Strong binding generally restricts downward movement, although transport may still occur through preferential pathways, erosion or movement of contaminated soil particles.
Research into the effects of herbicides on soil microbial communities is continuing. Some studies and reviews report changes in microbial composition or function, while the extent and practical significance of those effects differ according to the herbicide, formulation, dose, soil and farming system. Researchers have argued that changes to microbiomes may influence nutrient cycling and other plant–soil relationships.
It would therefore be too simplistic to claim that glyphosate always washes directly into the root zone and locks up nutrients. The environmental behaviour is more complex than that.
For me, this uncertainty does not justify complacency. It supports taking a precautionary approach, particularly when we have workable alternatives.
The Debate About Human Health
The potential human-health effects of glyphosate remain disputed.
In 2015, the International Agency for Research on Cancer, an agency of the World Health Organization, classified glyphosate as probably carcinogenic to humans. Its assessment was based on limited evidence in humans, sufficient evidence in experimental animals and strong evidence of genotoxicity.
IARC’s classification is a hazard assessment. It considers whether a substance is capable of causing cancer under some circumstances; it does not calculate the likelihood of cancer arising from a particular dose, product or pattern of exposure.
The Australian Pesticides and Veterinary Medicines Authority has reached a different conclusion. Its current position is that registered glyphosate products are considered safe when used according to their label directions and that there is no reliable evidence that those products pose a cancer risk to humans under approved conditions of use. The APVMA states that it continues to monitor emerging scientific evidence.
Peer-reviewed epidemiological studies have also produced differing results. One 2019 meta-analysis reported an increased relative risk of non-Hodgkin lymphoma among people in the highest glyphosate-exposure groups. A later meta-analysis found no clear association with non-Hodgkin lymphoma overall, although it concluded that an association with one particular subtype could not be ruled out.
In 2018, Cancer Council Australia called for an independent Australian review, arguing that IARC’s findings provided legitimate grounds for concern, particularly in relation to occupational exposure.
Court decisions, regulatory approvals and individual studies do not each provide the final scientific answer. Nor is it accurate to suggest that every exposure inevitably causes harm.
It is accurate to say that respected scientists and institutions have interpreted the available evidence differently.
I am entitled to take those concerns seriously. Our decision not to use herbicides does not depend on waiting until every researcher, regulator and chemical manufacturer reaches unanimous agreement.
Can Herbicide Use Affect Grapes?
A field study published in Food Chemistry in 2016 investigated the effects of glyphosate treatment on Ancellotta grapevines.
At harvest, berries collected from treated plots had lower pH and anthocyanin concentrations and higher titratable acidity than berries from untreated plots. The researchers did not find corresponding differences in anthocyanins, other flavonoids or phenolic acids in the resulting wines.
The authors concluded that glyphosate treatment “may affect fruit metabolism and nutritional value in non-target plants”.
This was one field study involving one grape variety. It does not prove that every glyphosate application will alter every grape or finished wine.
It does, however, provide credible evidence that the effects of undervine herbicide use may not always stop with the weeds being targeted. It also presents a legitimate reason for further independent research.
For me, fruit quality cannot be separated from the biological health of the vineyard in which that fruit is grown.
Our Approach at Weathercraft
Hugh and I have pursued improvements in fruit quality and vineyard health from the first day we set foot on our property.
The farm had been well managed before we took it over in 2016. However, its previous agricultural methods were conventional and relied on chemical inputs.
Our initial soil tests revealed compacted ground, excessive levels of certain macronutrients, scarce micronutrients and limited biodiversity within the vineyard.
Since taking over the property, we have never used herbicides in the Weathercraft vineyard.
Rather than applying herbicide beneath the vines, we have focused on rebuilding soil health from the ground up. Our approach centres on biological inputs, mechanical weed management, increased biodiversity and vineyard practices intended to support a more balanced and resilient ecosystem.
The process requires more time, labour and financial investment than spraying a strip beneath each row. It is not the easiest or least expensive method in the short term.
For us, however, the benefits of farming without herbicides far outweigh those costs.
Quality Includes How the Fruit Is Grown
Consumers are becoming more conscious not only of where their food and wine come from, but of how they are grown.
I do not believe the quality of a wine should be judged solely by what is in the glass. Quality also includes the condition of the vineyard, the way the soil is treated and the responsibility a producer accepts towards workers, customers, neighbouring ecosystems and future generations.
I am not suggesting that every vineyard can adopt exactly the same practices. Climate, scale, terrain, finances and available labour all affect the choices open to an individual grower.
However, those practical challenges should not prevent the industry from questioning established practices or investing in better alternatives.
The intensity of what we do to pursue fruit quality, protect our environment and honour our responsibility to our customers is completely worthwhile.
Quality comes at a price, but that price need not be extraordinary.
Farming for the Next Generation
For Hugh and I, the decision never to use herbicides in our vineyard was a simple one.
This land we care for—and this vineyard—is for the next generation and the one after that. What we do today will affect the land inherited by our daughter and, perhaps one day, her children.
Every decision we make is guided by that responsibility.
Research Reference used in Article
Donnini, S., Tessarin, P., Ribera-Fonseca, A., Di Foggia, M., Parpinello, G.P. and Rombolà, A.D. (2016), “Glyphosate impacts on polyphenolic composition in grapevine (Vitis vinifera L.) berries and wine”, Food Chemistry, Volume 213, pp. 26–30.