Our dubious war on weeds

My breathing is loud and steady through my respirator. My hands sweaty within the elbow length PVC gloves into which the sleaves of my fluorescent orange overalls are tucked. Inside this spacesuit, wielding a wand that spurts toxic chemicals, I imagine I am an alien engaged in the Sisyphean task of making the perfect front garden of planet Earth to impress my intergalactic neighbours.

My target is St John’s wort. The only noxious weed found in this gorgeous patch of remnant native grassland on the side of a state highway, in the Midlands region of lutruwita/Tasmania. This wildflower-speckled patch makes up some of the less than 17 per cent native grasslands left in lutruwita after white colonisation. Weed invasion is one of the greatest threats to these native grasslands, so controlling them is a primary objective for land managers such as myself. Every year throughout Australia, $300 million is spent on weed control on public lands.

St John’s Wort is native to Europe, Western Asia and Northern Africa and was introduced to Australia in the 1800s. The publicised origin story of this plant as a noxious weed in Australia has a peculiar fairy tale aura: the first ‘outbreak’ occurred in Bright, Victoria, where it purportedly spread from the garden of an ‘old lady’ growing the plant for medicinal purposes.

Like most weeds, St John’s Wort is an early coloniser of disturbed habitats. Other properties that allow it to spread easily are its high seed production, long viability of seeds, adaptable growth, toxicity to grazing animals and ability to reproduce and recover from long-lived rootstock. St John’s Wort caused much consternation to graziers and governments in the 1800s, when it poisoned sheep and displaced crops—sometimes to the point that the cost of control exceeded the value of the land it had taken over.

As a species, St John’s Wort not only benefitted from its initial introduction to Australia by settlers but also by how settlers managed the land. It found in the newcomer humans a great partner in colonisation. Sheep and cows would preferentially graze tasty species such as the native kangaroo grass and introduced pasture grasses, leaving space for the St John’s wort to thrive. Settlers disturbed landscapes by land clearing, then brought in stock bearing weed seeds in their hair and faeces. Forests were felled and roads cut, opening more and more places for the plant (and others like it) to flourish.


Weeds, simply defined, are plants growing where they are not wanted. In today’s value system, native plants are favoured in ‘natural’ settings, and thus exotics are considered weeds in these settings. Most of the noxious weeds we target today have evolved as primary colonisers of newly disturbed land. Following a landslide, a fallen tree, a herd of elephants or a bulldozer, plants with weedy qualities are the first to take over. Their seeds disperse freely on the wind or in bird poo, they grow quickly to take advantage of openings before other plants steal their sunlight, and they are extremely fecund, sending many seeds out to find the next site of disturbance. These early colonising plant species, when they are unwanted and exotic, are the types of weeds considered in this essay.

Though variable depending on individual species and the land they occupy, the impacts of weeds can be devastating. In some cases, an exotic in an otherwise native ecosystem may only trouble human aesthetics and values. In others, a weed species may become dominant in an ecosystem, causing the local extinction of other species, changing the structure of the vegetation and influencing the fire regime and other patterns of disturbance. Weeds can impact sacred sites, reduce the productivity of agricultural land, and alter the habitat of native animals.

Throughout the history of Western agriculture, we have facilitated the evolution of both plants we rely on and plants we despise (one species commonly being both weedy and desired by different people in different contexts). Some of the weed species that every farmer knows today were also exploiting the habitats created by people engaged in the first known trials of grain cropping some 23,000 years ago, on the shores of the Sea of Galilee. Since then, weeds have been travelling with and adapting to the development of Western agriculture. The Australian continent, settled long before this time by people who learnt to manage the landscape in a fundamentally different way, remained relatively free of this band of ancient weeds until European colonisation 200 years ago, which brought both weeds and the agricultural practices that formed them.

As such, the ‘war on weeds’ can be framed as either an act towards decolonisation, or an expression of xenophobia and the very colonial desire to wield control over landscapes. Weedy landscapes can be considered the truest form of wilderness: unmanaged, rebellious and showing voracious will for life. By contrast, native ecosystems were traditionally managed and hold invaluable natural and cultural heritage.


Though it is tempting to portray them as such, it is crude to use weeds as a metaphor for colonial humans: the lives of humans and plants are too profoundly entwined to be untangled into parallel lines. Rather, weeds are beings who have chosen humans, specifically, in this instance, settler colonial humans of a particular agricultural lineage, as their partners (Michael Pollan writes brilliantly on the way plants use humans in The Botany of Desire: A Plant’s-Eye View of the World).

Learning from our partners may tell us a lot about ourselves, yet we speak of them in a militaristic lexicon: weeds ‘invade’, and we fight them in an ‘eternal war’. The crusade of conservationists and agriculturalists against introduced plants is especially troubling when it involves spraying chemicals that are, unsurprisingly, also unhealthy to humans and ecosystems. If this must be a war, and it is to be successful, it will have to be a revolution that upturns our way of being with the land.

The sustained growth of early coloniser weeds in one place requires continued disturbance—otherwise longer-lived, more competitive plants will take over. Likewise, the doctrine of infinite economic growth demands continuous transformation of primary resources into capital, while the flexibility of capital allows us to outsource disturbance to other places and times. So, human disturbance becomes constant, and weeds become abundant at our least cared-for places: the peri-urban wildernesses of tips and abandoned sites of industry and extraction; liminal spaces such as roadsides, waterways and borderlands; and poorly managed farms.


In my front garden I have planted the native bulbine lily (Bulbine bulbosa); which produces delicious tubers (apparently—I am yet to harvest mine). Like most useful native plants, and in contrast with most of the food plants we currently use, it is perennial—it can live many years and be grown and harvested with minimal inputs while building topsoil. The bulbine lily thrived in the diverse grasslands and woodlands maintained by Aboriginal people in vast areas across South-Eastern Australia before their practices were violently interrupted by invasion. This species, as well as other Aboriginal food and fibre plants, has been selectively bred by Aboriginal people, who propagated individuals with desirable qualities. Thankfully, Aboriginal initiatives are bringing back practices that encourage these species and the tradition of harvesting them.

Synanthropic plants are plant species that rely on human-made habitats but are not desired by humans. These are so historically important in the Western agricultural context that they feature in Aesop’s Fables and the Bible. Yet in my reading of the culture and relations to plants of Aboriginal people across Australia and in my conversations with Indigenous land stewards, I have not yet found a species that fits this definition in the pre-colonial Australian context. That the Aboriginal cultures of this continent have not created ‘weeds’ through tens of thousands of years of influence on ecosystems reflects beautifully on their long-lived relationships with Country.


Native plants, having evolved on the Australian continent, have the wisdom of the land to share with us, along with the human culture with which they co-evolved. We can learn ways of being in place from them. Australia has some of the oldest and least fertile soils in the world. Perhaps counter-intuitively, this leads to an incredible diversity of species as plants find creative ways of accessing the limited resources available.

South-western Australia is a recognised biodiversity hotspot of the world, possibly because the poverty of its soils has forced plants to become highly specialised to tap into particular sources of water and nutrients. In these low-fertility ecosystems, much energy goes into growing highly specialised root systems, while upwards growth is slow and resource use conservative. Many species build symbiotic relationships with mycorrhizal fungi, which assist access to nutrients and complex relationships with pollinators. That humans find the resulting diversity incredibly beautiful is telling—we can and do appreciate diversity. These ecosystems ask us to embrace diversity more, in our social lives as well as our land management and agricultural systems.

While native plants are well-adapted to infertile soils, many introduced species—whether weed or crop—require heightened soil fertility to gain an advantage. High fertility is conducive to monoculture, as where resources are abundant, the more competitive plants can grow quickly and monopolise resources, outcompeting other plants. In such a rich environment, plants rely less on symbiotic relationships to reach difficult to access nutrients.

Rather than relying on mycorrhizal symbiosis to gain nutrients, cropped plants are fed all they need in fertiliser. Introduced species that evolved in more nutritious soils—and are removed from the competitors and predators with whom they evolved—thrive in habitats of elevated fertility. The unregulated access to our continent’s natural resources in a laissez-faire economy likewise favours a weedy class of winners, leaving behind a diverse bunch of struggling humans. That this weedy class is not held back by relationships embedded in the landscape creates devastating ecological effects. A preferable reality exists in which the use of resources is regulated and shared, cultural roots run deep into the land, and the growth of relationships is favoured over the growth of wealth. Many Aboriginal communities uphold this ethos: their culture does not promote the accumulation of wealth by a small number of individuals.

Native grasslands, particularly rich in useful plants, require disturbance with a regularity only possible through human management. This management traditionally takes the form of harvests and cultural burning. Cultural burning is regaining traction today, and regenerative agricultural practices show stock can be used to a similar effect. These are gentle forms of disturbance compared to the violence of annual cropping and the heavy-handedness of mainstream grazing. Cool burning operates like pruning: biomass is removed but most plants survive to grow more vigorously following the next rains. Strategic grazing concentrates grazing in a series of small patches, ensuring that all plants are nibbled rather than just the most palatable before allowing each patch to recover while stock is rotated across the landscape. Australian ecosystems have evolved with people and encourage us to collaborate with them to maintain their species richness, their heterogeneity across the landscape, and the continent’s suitability to human life.

When I harvest the bulbine lilies I have planted, perhaps in two years’ time, I will pull out the plant, take the middle tuber—not the oldest and strongest nor the youngest and freshest—and press the plant back into the ground, in a method learnt from palawa woman Trish Hodge of NITA education.

Native plants from each part of the continent can offer grains, tubers, leaves and fruits for human bellies. Many plants encourage us to use them, as sensitive harvesting regimes increase their productivity. This has been scientifically proven with greenhoods (Pterostylis sp.) and bunge (Patisace sp.) and has been long known by Aboriginal people who understand the right harvest method for many other species.


To the perceptive farmer or gardener, weeds are a way for the land to communicate its needs. Great mullein indicates that the soil is acidic, Chilean needlegrass that it is low in nutrients, and flat weeds and the proliferation of unpalatable species such as thistles and St John’s wort that the pasture is overgrazed. Whether land is managed for agriculture or native biodiversity (or, as in pre 1788 times, both), if it is managed well, it will have fewer needs and fewer weeds.  Fewer chemicals will be needed, and less time grubbing, cutting and pasting, chainsawing or bulldozing plants.

At present, this work is necessary to ward off the worst of the problem, remove already well-established weeds, and preserve the integrity of remnant native systems such as the grasslands I work with. But we are treating a symptom. The herbicides we use are like antibiotics that weaken all the symbiotic relationships in our bodies even as they heal. They give us some breathing room, but so long as we continue to aggravate the wounds on the skin of our continent, we continue to invite pathogens in.

All our environmental problems require a radical change in how we think about resources and land. Before 1788, there was no wilderness: management for biodiversity was also management for the availability of food, fibre, wood and medicine. Harvesting these things was also a form of management. As settlers, we have created many wildernesses: those for worship, those for recreation, and weedy landscapes formed as externalities of production.

Both regenerative agriculture and traditional Aboriginal land management practices offer strategies to manage land as both a provider of resources and a biodiverse ecosystem. In a globalised world, we must decide as a society what we value in our landscapes and will always have to do some level of weed management to uphold this. While we currently declare the land, nutrients and water used by weeds ‘waste,’ we can use the weed material we remove during management. Wood, medicine, food and biochar are all resources we can derive from weeds. Not only would this lower production pressures elsewhere, but is also one way to offset the significant costs of management. Management that uses these resources could provide a new economic stream for those practicing weed management, allowing more money to be spent on slower but more environmentally sensitive weed management techniques.


I breathe a sigh of relief after removing my condensation-filled mask and grubby overalls, surveying the field I have stained pink with puffs of herbicide. I wish I had a team of five with me, and we had pulled the plants out rather than spraying them, using our harvest to make tea and tinctures we could sell or give away. For now, I take a small bounty of little yellow flowers home to make gifts for my friends.

Suyanti Winoto-Lewin

Suyanti Winoto-Lewin is an ecologist, land manager and environmental activist based in nipaluna/Hobart.

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  1. Such a beautiful and well articulated expression of the impacts of weeds in our ecosystems and the greater problems these weeds are communicating. Simply beautiful and informative!

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