Seeing ‘Weeds’ with ‘New Eyes’ -1

Marcel Proust, once said: “The real voyage of discovery consists not in seeking new lands but seeing with new eyes.” I suggest we look at weeds in this way in this 21st Century. As a weed scientist, I reflect upon some ideas that have shaped our recent discourses on weeds. It seems to me that the emerging generation of weed scientists may benefit from a dip into this history. As someone said: ‘without history, man is nothing’.

“…One longs for a weed, here and there, for variety; though a weed is no more than a flower in disguise, which is seen through at once, if love gives a man eyes…” James Russell Lowell (c. 1890)

“…It is time for us to eliminate weeds from our cultivated lands. But we should understand why we do it, and what we’re doing. Nature has a reason for allowing weeds to grow where we do not want them. If this reason becomes clear to us, we will have learned from Nature how to deprive weeds from their ‘weedy’ character; that is, how to eradicate them from cultivated land, or rather, how to improve our methods of cultivation so that weeds are no longer a problem…” Ehrenfried Pfeiffer (c. 1950)

The first quote pleads for people to ‘open their eyes’ and appreciate Nature, in which weeds are an essential part. Poetic freedom allowed James Russell Lowell to promote a profoundly sympathetic view of weeds, instead of looking at them negatively, as always causing problems to humans. The second quote, from a soil scientist, who pioneered organic agriculture in the USA, recognized that some plants might become a nuisance when they interfere with the growth of crops or man’s other activities. Dr. Pfeiffer suggested that such ‘weeds’ need to be eliminated from arable land, but we should do so with a good understanding of why they are there in the first place.

Both viewpoints are essential in looking at weeds with new eyes. Many weed scientists and other ecologists would agree that weeds have been poorly understood for the past two centuries. These plants have also been subject to excessive malign, primarily driven by misconceptions and perhaps, even influenced by the prevalent worldview that everything on earth has been created to be subdued and exploited to satisfy man’s selfish interests.

The relationship between weeds and men is an old one; however, it is changing fast. There have been increasing public concerns about the effects of land-clearing, over-development, overuse of herbicides, and other destructive farming practices, as part of our goal of assuring human food security. Such concerns have encouraged some to think critically about whether we ought to and need to continue maximum control programs against plant taxa that only pose problems under certain sets of conditions.

A critical issue for Weed Science is the persistent and uninformed slandering of colonizing plants (weeds) by some people, which inhibits others from admiring them and appreciating their redeeming values and thereby welcoming them into our lives and environment. As discussed by Robert Zimdahl (1999), common definitions of a weed include: “a plant, which has a detrimental effect on economic, conservation, or social values” and, “an undesirable plant, which is out of place”. Such definitions are inappropriate in a scientific discipline, because they are anthropocentric and culturally-biased. They mislead by creating a negative perception that all weeds are bad, under all circumstances. Addressing this anomaly requires recognition of the beneficial effects and values of weeds, as part of the Earth’s rich bio-diversity.

Are Weeds ‘Plants Out of Place’?

In the 1960s, our founding fathers steered the discipline well clear of ludicrous ideas, such as ‘plants out of place’. In articulating the scientific and ecological basis for explaining weeds, they pointed out that these organisms are no more than taxa with strong colonizing abilities adapted to natural or human-disturbed habitat (Baker, 1965; Bunting, 1965; Harlan and De Wet, 1965; De Wet, 1966). They are the first occupiers of newly cleared land. The more you disturb the land, the more you create opportunities for these highly successful “pioneers of secondary succession” — nothing more; nothing less.

When moved by natural dispersal agents (e.g., wind, water, animals) or by the human agency, and introduced into new environments, ‘pioneering’ taxa can successfully establish populations and increase in abundance within a short period. Attributes that allow them to do so (see Baker’s List of ‘The Ideal Weed’, Baker, 1965) include their innate genetic systems and reproductive capacity to produce seeds or other propagules under most conditions, and fast growth to reproductive maturity. Colonizer taxa are also capable of stress tolerance and plasticity, which allow them to adapt quickly to unfavourable biotic or abiotic environments. The absence of natural enemies in the new environment, at least initially, also helps these taxa to colonize a new habitat.

Mis-information is rife on the negative impacts weeds have on the environment or on biodiversity. The negative publicity has been increasing. It is rare to find a biology lecturer, teacher, or an ecologist, who would has the courage to mention the virtues of weeds. They are either scared; or unsure, because there are powerful voices advocating the opposite view. These negative viewpoints also have taken deep root, over a long period. At weed conferences, one often hears speakers flippantly indulge in the use of pejorative terms like “damned weeds”; “bloody weeds” drawing approval from audiences. It is a fashion, although such words are not in the lexicon of enlightened ecologists or weed scientists.

The overwhelming negative attitudes towards weeds, rampant in some Western countries, including Australia, the USA and Canada, appears to be a form of xenophobia (dislike of anything strange or foreign). The notion, that weeds are plants ‘out of place’, is very American, as the historian Zachary Falck (2010) noted. It arose in the 1850s out of the aspirational dream of the American middle-class in creating cities, which needed to look ‘sanitary’ and ‘orderly’. The early American cities, mostly in the East coast, had been influenced by the streetscapes of European cities, from which the ancestors of the settlers had come. As opposed to the attractive and colourful wildflowers, which beautify parks, sidewalks and median strips, untamed growth of weeds was blamed for ‘disfiguring’ open spaces and for the ‘imperfections’ of urban life in the cities. Tim Creswell (1996; 1997) explains how inherently flawed the ‘out of place’ idea is, as follows:

“…the notion that everything has its “place” and that things (people, actions) can be “in-place” or “out-of-place” is deeply engrained in the way we think and act. Such is our acceptance of these ideas that they’ve achieved the status of common sense or become second nature to us. Common sense produces the strongest adherence to an established order…”

“…People act as they think they are supposed to; they do what they think is appropriate in places that are also appropriate. It is therefore essential for powerful groups in any given context to define ‘common sense’ and that which goes unquestioned. When individuals or groups ignore this socially-produced common sense, they are said to be “out-of-place” and defined as deviant…”

We brand some plants ‘out of place’, because, we have firstly ourselves defined in some abstract way, elements of our immediate environment as ‘proper places’, and these would demand ‘appropriate behaviour’. Such a notion may be satisfactory for some of our living spaces, such as home gardens, flower beds, and turfed lawns, kept neat and tidy, in which weeds may be accused of de-spoiling the tidiness. One may also call agricultural fields ‘proper places’, because we use them to produce our food and fibre. By the same argument, one may call natural or pristine areas, with little human interference, as ‘proper places’ from a human point of view.

But it is a stretch to call all wilderness landscapes with we interact ‘proper places’? Such places, being part of nature, often not interfered by man’s activities, pose many challenges to humans, unless you are a skilled survivor in the wilderness. Teeming with life, including wildlife, wilderness areas are not likely to respond in the way we perceive the world to be.

What is “out of place” depends on the context and who is making this subjective assessment, based on personal experiences. Thus, within our discipline, we create lists of plants labelling them as ‘environmental weeds’, ‘horticultural weeds’, ‘agricultural weeds’, ‘ruderal weeds’, ‘urban weeds’, ‘sleeper weeds’, and so on. Many of these categories have no scientific basis. They are just descriptors. From an environmental perspective, crops could also be viewed as weeds. From a farmer’s perspective, native plants growing in fields could potentially be weeds, particularly if they produce large numbers of offspring and are hard-to-kill. As Stephen Radosevich and Jodie Holt (1967) said: “Any plant can be a weed, and no plant is always a weed. As a consequence, some plants may be considered weeds, and hence, undesirable to have at particular places and at specific times”.

To appreciate weeds, one must look at them through ‘new eyes’, an ecological lens, and frame of mind. The fact that weeds are colonizers with extraordinary abilities is the accepted wisdom in ecology. Nevertheless, as a group, these plants have been subjected to relentless attacks through negative publicity and the liberal use of militaristic metaphors e.g., ‘‘invasions’. The public can be excused for being scared out of their wits and common sense. Attitudes towards weeds must change, and this will happen only if weed scientists open their eyes and look closely at the organisms we have learned to despise.

The resilience of weeds, their tenacity, and the capacity to adapt to environmental disturbances need to be recognized not only as harmful but also as potentially beneficial. I suggest that the very success of these plant taxa in the environment is also their weakness. Their verdant growth and abundant presence, in some situations, conflict with human objectives, and this is why they have become targets for our technology. Perhaps, this understanding would help modify our attitudes allowing us to avoid creating conflicts with potentially useful plant taxa and getting into situations from which we cannot win.

It is necessary and good for all scientific disciplines to realign their focus and objectives from time to time. Weed Science has reached that stage. While there is a vast amount of disparate literature, the future requires a convincing ‘body of knowledge’ of the utilization of colonizing species to be established, so that present and future generations will benefit from that knowledge.

Humans — the ‘weediest’ of all species

“…The word weed is taken to mean a species or race, which is adapted to conditions of human disturbance. By this definition weeds are not confined to plants. Animals such as the English sparrow, the starling, the “statuary” pigeon, the house mouse, Drosophila melanogaster, and others are especially fitted to environments provided by human disturbance. Indeed, perhaps no species thrives under human disturbance more than Homo sapiens himself. In this ecological sense, man is a weed…” Harlan and De Wet (1965).

The reason I cite Jack Harlan and Johannes De Wet is to remind the new generation of weed scientists that because we ‘thrive on human-modified landscapes’ humans are clearly ‘weeds par excellence’.

We are the only species that does not have to adapt to the environment. We change and/or modify our environment to suit our needs. For example: we heat our homes, air-condition them, wear clothes, drive cars, etc. On the other hand, colonizing species have the inherent capacity to adapt fast to any new environment. Often introduced to different continents deliberately or accidentally by humans, weeds are trekking the globe as the’ shadows of men’.

The same attributes that make a plant highly successful in getting established in new environments (vaguely called ‘invasive’) will be sought after under a different set of circumstances. The way forward is to broaden our understanding of colonizing plant taxa and their crucial ecological role in biological communities. To achieve this objective, our journal will promote more in-depth ecological studies and critical analyses of weeds, instead of just publishing papers on pure and straightforward weed control.

A ‘War with Weeds’ is untenable

The fact that weeds cost farmers more than any other major pest category has engendered a ‘war mentality’ in dealing with weeds, which is unfortunate. Given that cropped fields are continually-disturbed for production reasons, the occurrence of colonizing taxa is inevitable. But to say that we should deal with weeds like a military campaign is an idea fraught with danger. It is also an inappropriate strategy that includes an unattainable goal — 100% weed control forever.

Developed over centuries, agriculture has ample strategies and tactical tools to deal with weeds, which include tillage, hoeing and other methods of land preparation, active cover cropping, crop rotation, inter-cropping, and maintaining organic residues of even pioneer species to cover the soil and add organic matter, but not to set seed. Declaring ‘all-out war’ on weeds, mainly with chemicals, may yield ‘clean’ and ‘weed free’ fields and good harvests, but for how long will these last? Overuse of herbicides has already backfired with the widespread development of herbicide resistance in weeds on a large-scale, across the globe, threatening agriculture in many countries (Heap, 2019).

Biologists need to continuously reflect upon the ethical dimensions of the language they use when communicating with the public on weeds and other species, often derided as ‘invasive’. As Larson (2005) questioned: “Is the language of ‘war’ likely to promote social cohesion and, consequently, effective and appropriate action towards weeds?”

The militaristic and combative metaphors used within ‘invasion biology’ are unsuitable because: (1) they lead to a narrow perception of weeds and certain animals as marauding armies of ‘invaders’; the idea is far from the truth! (2) they contribute to a profound social misunderstanding of weeds as nothing but plunderers of our resources, leading to xenophobia, and loss of scientific credibility; and (3) they reinforce militaristic patterns of a ‘winnable war’ against all weeds, an attitude that is counter-productive for both conservation and restoration of native vegetation.

While ‘war’ and ‘invasion’ metaphors may motivate some people into action against weeds in the short term, they are likely to fail in the long term. Alternatives to militarism will better promote realistic weed management and conservation goals in a multicultural context (Larson, 2005). I add that removing such jargon from the Weed Science lexicon will allow people to be optimistic about having a better relationship with weeds (Chandrasena, 2015).

‘War with Weeds’- is the wrong choice of words to describe how we should manage weeds. This phrase is often bandied around in TV, radio, books, and magazines. The attraction is clearly in the alliteration, the repetition of the letter ‘w’, which makes a snappy phrase. Evans (2002), in his historical analysis of weeds in Canada, used it as his book’s title, but to convey a wholly different message.

The ‘war’ analogy probably got entrenched in the mid-1940s, following the military successes of the Western-allied forces in 1945 in finally annihilating Nazi Germany’s war machine. The end of World War II coincided with the discovery of the first synthetic herbicide, 2,4-D in 1944, which then began to be used widely for weed control. Much of the work was done during the war, but the research was not allowed to be published until the war was over. Pest control, those days, was also seen as a requirement for the total annihilation of the target pest, so that the pest populations may not ever recover. The basis for the obliteration mentality was the undisputed success of the large-scale use of the first-ever synthetic insecticide, DDT in 1939, in controlling the malarial mosquitoes and typhus (spread by body lice) among the Allied forces in various battlefronts.

The total annihilation of a pest organism was the main goal, but it was an unachievable one, both scientifically and practically. The possibility of large-scale heavy hitting with synthetic chemicals may have adverse effects on humans, and non-target animals were not generally realized until Rachel Carson’s Silent Spring (Carson, 1962).

In the early-1960s, Rachel Carson raised the issue of excessive losses of birds, creating a heart-rendering image of a ‘silent spring’, directly pointing the finger at the overuse of pesticides. Residues of some pesticides persisted in the food chain, reaching higher concentrations (bio-accumulation), which resulted in more severe effects at successively higher trophic levels. Worryingly, pesticide residues were identified as the cause of rapid population decline, particularly in birds of prey, such as the peregrine falcon and sparrow hawk, through the thinning of eggshells. The offending chemicals, mainly organochlorine (OC) pesticides, including DDT (dichloro-diphenyl-trichloroethane), have now been banned in many countries, but they are still used in some poorer countries of the world.

Rachel Carson’s observations were quite controversial at that time; she was ridiculed, and her predictions dismissed. The corporate world paid millions to have her silenced. But, eventually, the love of bird songs won out. People read her book, grieved at the prospect of a ‘silent spring’, spoke up, and insisted on regulations that eventually brought a ban on DDT and strict legislative controls on the uses of all pesticides. Nevertheless, this was a period during which powerful chemicals, insecticides, fungicides and herbicides, were being discovered, and the idea that an all-out war would solve pest problems became further entrenched in the minds of the proponents. In the post-war USA, it was common to talk about obliteration or annihilation of the enemy. With a bit more common sense, phrases like ‘war’ might have been left out from the lexicon used in communicating weed or pest control messages to the public.

To presents a largely human-caused problem as a confrontation between humans and weeds in a way that alienates each other is ethically wrong. The human culpability (humans, as a major cause of the global spread of weeds) is mostly removed in this narrative. It reflects the flawed prevalent thinking in our modern societies that all ills are someone else’s faults and never ours.

From a pragmatic viewpoint, this mentality, foolishly describes a situation from which there are no true winners. Humans may subdue some colonizing species here and there, but surely, it is unlikely, ever, to eradicate problematic species without causing other types of environmental harm. Hence, instead of pursuing the delusion of winning a war with weeds, we ought to aim for a negotiated peace; a multi-faceted co-operation between weeds and us; and a peaceful co-existence (Chandrasena, 2007; 2017). Not to do so would be counter-productive in the long-run.

To successfully negotiate peace, a deeper ecological understanding of the strengths and weaknesses of the ‘potential foe’ is a must. The history of Weed Science records that our founding fathers, decades ago, argued most persuasively for such an understanding with more in-depth ecological studies on weeds (Harper, 1960; Bunting, 1960; Baker, 1965; Baker and Stebbins, 1965). They were, of course, motivated by common sense and scientific rigour alone and unburdened with the need for hyperbole.

Speaking at the 22rd Asian-Pacific Weed Science Society Conference, in 2011, David Low challenged the notion of a ‘war economy’ for weeds. He explained that the primary reason for using this analogy in Australia is that it allows the protagonists (bureaucrats) who control budgets, to shift spending in preferred directions. I agree with him.

“…As is the case in any real ‟war’ situation, “War!” effectively shreds our normal investment priorities, and such a situation can be used to create the urgency needed to bulldoze away the messy contingencies that support future life. One of the most overlooked consequences of this manipulation is that it disconnects the trajectories and social priorities that give rise to weeds from the costs (social and ecological) of controlling or preventing them.

As such, the taxation imposed by government to prevent and/or control weeds is no longer transparently connected to the dislocating human activities that give rise to weeds. The disconnecting social activities are therefore not subject to social critique. Put in economic terms, we might say that there is a “persistent market failure‟. The analysis undertaken here, however, suggests that what is really persistent is a lack of ecological literacy…”

“…The centrality of the “war” analogy in the weed discourse largely explains why weed preventing and/or controlling, presently attracts mass market support and commands the allocation of significant social resources. For example, the wholesale value of herbicide sales in Australia for 2008–09, a drought year, was $1.1 billion. As this figure demonstrates, not only do humans invest a great deal of their time and money extracting victories “over‟ nature, but they are also willing to spend a great deal of time and money “protecting‟ their preferences for a limited range of life — after all, the purpose of herbicides is to efface future life that “threatens” prevailing human priorities. What perhaps needs to be understood clearly, therefore, is how partial the understanding underpinning the “war on weeds‟ analogy really is. Circumspection is required…..” David, Low (2011)

Literature Cited

Baker, H. G. (1965). Characteristics and Modes of Origin of Weeds. In: Baker, H. G. and Stebbins, G. L. (Eds.) The Genetics of Colonizing Species. Proceedings 1st International Union of Biological Sciences Symposia (General Biology). Academic Press. New York. 147–169.

Baker, H. G. and Stebbins, G. L. (Eds.) (1965), The Genetics of Colonizing Species. pp. 147–172, Academic Press, New York.

Bunting, A.H. (1960). Some reflections on the ecology of weeds. In: J. L. Harper (Ed.) The Biology of Weeds. Blackwell Scientific, Oxford. pp. 11–25.

Carson, R. (1962) Silent Spring. Boston, Cambridge, Mass: Houghton Mifflin, p. 368.

Chandrasena, N. (2007). Liabilities or assets? Some Australian perspectives on weeds. In: Kim, K.U. et al., (Eds.) Utility of Weeds and their Relatives as Resources, pp. 9–56. Kyungpook National University, Daegu, Korea.

Chandrasena, N. (2014). Living with weeds — a new paradigm? Indian Journal of Weed Science, 46(1): 96–110.

Cresswell, T. (1996). In Place/Out of Place: Geography, Ideology and Transgression. Minneapolis, University of Minnesota Press. 201 pp.

Cresswell, T. (1997). Weeds, Plagues, and Bodily Secretions: A Geographical Interpretation of Metaphors of Displacement, Annals of the Association of American Geographers, 87(2): 330–345.

Davis, M. A. (2011). Do native birds care whether their berries are native or exotic? BioScience 61: 501–502.

Davis, M. A. and Thompson, K. (2000). Eight ways to be a colonizer; two ways to be an invader: a proposed nomenclature scheme for invasion ecology. ESA Bulletin, 81: 226–230.

Davis, M. A. and Thompson, K. (2001) Invasion terminology: should ecologists define their terms differently than others? No, not if we want to be of any help. ESA Bulletin, 82: 206.

De Wet, J. M. J. (1966). The Origins of Weediness in Plants. Proceedings of the Oklahoma Academy of Sciences, 1966. 14–17.

Evans, C. (2002). War On Weeds in the Prairies West: An Environmental History. University of Calgary Press, Calgary, Alberta, 309 pp.

Falck, Z.J. S. (2010). Weeds: An Environmental History of Metropolitan America. University of Pittsburgh Press. p. 256.

Harker, K. N. and Donovan, T. O. (2013). Recent Weed Control, Weed Management and Integrated Weed Management (Editorial). Weed Technology, 27: 1–11.

Harlan, J. R. and De Wet, J. M. J. (1965). Some thoughts about weeds. Economic Botany, 19: 16–24.

Harper, J. L (Ed.) (1960). The Biology of Weeds. A Symposium of The British Ecological Society. April, 1959. Blackwell Scientific Publications, Oxford. p 256.

Heap, I. (2019). The International Survey of Herbicide Resistant Weeds. www.weedscience.org.

Jackson, T. (2012). The Cinderella economy: an answer to unsustainable growth? The Ecologist, 27th July 2012.

Kim, K. U., Shin, D. H. and Lee, I. J. (Eds.) (2007). Utility of Weeds and Their Relatives as Bioresources. Kyungpook National University, Daegu, Korea. p. 222.

Kiviat, E. and Hamilton, E. (2001). Phragmites use by Native North Americans. Aquatic Botany, 69: 341–357.

Kloot, P. M. (1983). Early Records of Alien Plants Naturalised in South Australia. Journal of Adelaide Botanic Gardens, 6(2): 93–131.

Larson, B. M. H. (2005). The War of the Roses: Demilitarizing Invasion Biology. Frontiers in Ecology and the Environment, 3(9): 495–500.

Lowell, J. R. (c. 1890). A Fable for Critic (p. 23). 2nd Edition. G. P. Putnam, Broadway, New York, p. 80.

Pfieffer, E. (1950).Weeds and What they Tell us. Biodynamic Farming & Gardening Association, Inc., New York, p. 96.

Radosewich, S. R., Holt, J. S. and Ghersa, C. M. (1997). Ecology of Weeds and Invasive Plants — Relationship to Agriculture and Natural Resource Management. 3rd Edition. Wiley-Interscience, USA. p. 589.

Zimdahl, R. (1999). Fundamentals of Weed Science, 2nd Edition, Academic Press, New York, p. 556.