Cheating to Win- Herbicides

A rising movement has focused on the dangers of glyphosate. The concerns seem to have settled primarily on the toxicity of the particular chemical, with a galaxy of various alleged health effects linked to this evil molecule. This modern obsession with contamination and ill health is really bemusing to me. It comes from a society which has enjoyed longer and safer lives than any in recorded history, with even ordinary people living in material comfort that would make a medieval king envious. Yet these people feel like they are entitled to cheat death and avoid getting cancer at 70 and instead continue to live it up until 90 without skipping a beat. To some degree cancer is the monster on everyone’s mind due to a generation of over screening and over-diagnosis making it appear that cancer rates were exploding, especially for breast and prostate cancer as these were the easiest to do mass screening on. Such efforts are now known to have led to diagnosis and treatment of mostly benign tumors that were unlikely to cause any issues, but because we lack the ability to discern dangerous from benign tumors reliably this screening led to aggressive over-treatment. Cancer is still mostly a disease of old age, so our aging populations also make cancer seem to become more common over time. Yet despite this age adjusted cancer death rates are steadily falling.

People know about the dramatic drop in lung cancer rates as people gave up smoking, yet lung cancer is still a common type and mostly caused by widespread air pollution that everyone breathes daily. If you point out all the other common and totally uncontroversial carcinogenic compounds in their everyday life, such as alcohol, processed meat, benzene in petrol and diesel, aflatoxin in the peanuts they eat, and you get a blank stare at best. Mention the even more potent carcinogens that people in the developing world are exposed to, such as the children that mine the cobalt in their phone batteries or the Chinese factory workers exposed to high levels of benzene to keep the prices of their products slightly lower, or even the many mothers of the world who cook over open fires and breath the smoke every day, and they will quickly change the subject. From their entitled perspective only their health and longevity matters, and chemicals like glyphosate are the real enemy.

The evidence of glyphosate causing cancer or any other significant health impact is pretty weak. Research is of course always incomplete and I love seeing better studies coming out over time, but if it was as bad as any of the other everyday substances listed above it would have been widely known by now. Focusing the argument on the supposed toxicity of glyphosate is counter-productive since it is the weakest angle to take, and misses a much wider range of more serious issues. Hypothetically the evil villain of the story, Monsanto (now Bayer) could develop a new herbicide that is unquestionably 100 % safe for people, meaning it can be sprayed with even more abandon and everyone lives happily ever after to a ripe old age. In reality the obsession with glyphosate means that in the short term farmers are likely to return to older herbicides with well-established toxicity issues. 2.4-D is often contaminated with highly carcinogenic dioxin. Atrazine is toxic and readily contaminates groundwater. Clopyralid is environmentally stable and often contaminates manure and mulch, tainting soil for years. Paraquat is strongly linked to Parkinson’s disease. Dicamba tends to evaporate and drift over large distances. Glyphosate has no such glaring toxicity issues yet it gets all the attention. Such pressure also encourages the development of new herbicides, which will undoubtedly be marketed as “safe” but will lack the decades of research scrutiny heaped on glyphosate and so may contain hidden surprises with large scale use.

Instead of glyphosate (and herbicides in general) being a problem because they are strong I would like to make the argument that they are a problem because they are weak. Modern industrial agriculture has become highly dependent on herbicides, especially glyphosate, since the shift to roundup resistant crops. These crops contain inserted genes that allow them to survive glyphosate applications, greatly simplifying weed control in large scale operations. That is until herbicide resistant weeds emerge, a process that happened with astonishing speed around the world. In response to that failure agribusiness quickly developed dicamba resistant crops, with resistant weeds emerging even more rapidly than with glyphosate. Just like plain penicillin that started as a magic bullet drug but is now close to useless due to antibiotic resistance it is likely that in the near future glyphosate will be abandoned due to widespread resistance in weeds. In the absence of viable herbicide/resistant crop combinations farmers either return to higher rates of mechanical tillage, which damages soil structure and contributes to erosion, or rely on using older and more toxic herbicides to clear fields of all vegetation between crops, again greatly accelerating erosion. Much of the worlds farming land is predicted to have about 60 more years of cultivation before erosion makes them useless, which is a slightly bigger problem than an almost undetectable rise in the cancer risk of rich westerners.

Another major weakness of glyphosate is where it comes from. When the patents for this chemical expired in 2000 and much of its production shifted to cheaper Chinese factories, along with the majority of other herbicides. In a world drifting into economic chaos and growing tension between China and its trade partners it seems unwise for such a critical component of industrial agriculture to come from so far away (along with the fuel to run everything and the machinery and parts). In the absence of a reliable and cheap supply of these inputs from Chinese factories industrial agriculture would fail overnight in many industrialised countries around the world, including Australia.

For small farm settings glyphosate and herbicides in general are also pretty weak tools. While they can kill targeted plants as advertised that doesn’t really count for much in the long run. Weeds that are problematic are normally common in the wider area, so even if your population is eliminated they will tend to return sooner or later. Weeds with significant seed banks in the soil will come back almost immediately, meaning that if you start spraying herbicide then you will be signing up for an eternity of that chore. Spray hard enough and you might get resistance emerge and at least there will be no point wasting your time and money spraying anymore. That said I do believe that herbicides can be a good example of a tool that can be used to cheat to win, that is utilised in a way that opens a path to systems that no longer require their use. The biggest potential positive use of herbicides is in ecosystem in transformation that permanently resets the system into a better form.

One place I have used glyphosate successfully is in reclaiming my waterways. When I started on my run down cattle pasture there were several seasonally damp gullies that had been colonised by giant Setaria grass. This fairly unpalatable species grows to about 2 m tall, produces abundant seed, and forms root balls about 40 cm in diameter. Physical removal would cause so much soil disturbance that it would quickly cause the seed bank to resprout and cause erosion in the event of water flow through the spaces. Burning the Setaria would produce smoke more carcinogenic than glyphosate, and would need to be done during a dry spell which means risking the fire getting out of control. Instead I waited for a drought so there was no moving surface water then sprayed the dense stands back. This left a thick surface mulch that suppressed seed germination, and left the root balls to hold the soil in place. I started at the most upstream point possible to avoid fresh seed being washed downstream into disturbed spots and only sprayed out about 10-20 m sections at a time so flowing water could not easily gain momentum. Once the Setaria was dead I replanted the area with better perennial species that established through the killed mulch. Once any Setaria seedlings got to a moderate size I hand hoed them out before they developed a large root ball, though occasionally they got away from me and were sprayed as they reached flowering to prevent seed set. With this approach I transformed these useless monocultures into some of the loveliest and most productive parts of my farm. I am currently pushing out a few final stands of para grass in these areas as well. It doesn’t produce as much seed, instead spreading by runners, making it an even better candidate for elimination. My waterways are also very isolated from other waterways so reinfestation is unlikely.

I also had a small patch of monoculture Setaria in one corner of my orchard. It was so dense it provided a habitat for rats that would destroy trees planted in the space. The stand was also sprayed out, with a very light application that was applied when it was commencing active growth in spring. This resulted in a 60-70% kill, with even lighter spot spraying taking out the remainder. The killed mulch rapidly flattened, making the space hostile to rats and allowing trees to establish. I periodically hand hoe the smaller regrowing Setaria, but now that the trees are well established along with more diverse understory weeds I am not as obsessed with rapidly eliminating the last of the Setaria. This grass needs full sunlight coupled with cattle grazing to form dense monocultures like I inherited. Once those monocultures are broken up and other species establish they never seem to regain their former vigour. Even long periods of no grazing seems to be weakening stands in other areas that were never sprayed. I have also sprayed narrow strips through some other Setaria stands to allow for direct seeding of fast growing wattles, which are now well above the Setaria that has closed around them. As the wattles reach maturity their shade will establish Setaria free zones where more wattle seedlings can grow on the edges, gradually pushing back the Setaria. That initial single minimal glyphosate application opened the door a crack and allowed the process of succession to get off to a much faster start.

Another useful situation for glyphosate and herbicide is in the control of woody weeds. For example I planted a decent number of Tithonia shrubs in my orchard. This is one of my best goat fodder shrubs but is a bit too rambunctious to leave in my orchard since it tends to layer and self-seed more than I like. Recently I have cut all these Tithonia shrubs down to the ground. If left they would rapidly regrow to 2-3 m tall within a year. I could potentially revisit all the root stocks every few weeks and carefully knock off every shoot until the root systems were exhausted, a fairly easy but very time consuming task. Instead I will wait for a modest clump of shoots to form and will spray them with glyphosate. My time then can be better invested in planting other trees all over the farm. Removing all the top growth and waiting for reshooting means a much smaller amount of herbicide will do the job since the plant has a compact and tender mass of shoots which efficiently absorb the chemical, and the plant is heavily reliant on new growth to avoid exhausting its root reserves.

In the long run we cannot rely on herbicides being available or affordable, a situation familiar to subsistence farmers around the world today. As such we must remain competent in methods of weed control and management that do not rely on such unreliable inputs. Physical removal is often the most tempting but human bodies are very limited in what they can do, especially when restricted to hand tools. Subsistence farmers need to be very conscious of maintaining their bodies since everything stops without physical capacity. Machinery is usually powered with fuels that are more toxic than glyphosate and poses its own risks of causing injuries. Plastic sheet mulching has become common for weed control but is another industrial product with an uncertain future. Organic matter mulching is usually also an output of oil powered machinery, though with forethought appropriate mulch that can be processed with hand tools can be grown where it is to be used such as in Inga alley cropping systems. Livestock probably represents the greatest untapped resource for weed control and management in a post-industrial future, though using it effectively is one of the more complex and demanding approaches. Fire also has great potential, especially in systems that produce surplus woody biomass. In a diverse system with trees of varying ages the woody branches from some trees can be concentrated around the base of plants that are removed by burning. Gathering wood this way can reduce the chance of the fire spreading uncontrolled.

Hopefully this journey has caused you to stop and wonder if you need to follow the herd and feel fear and loathing for glyphosate. I suspect many of us alive today will live to see its disappearance from everyday life, not because it was banned to save humanity from itself but because it was just one of many complicated, costly and ineffective tools that we were forced to abandon as the industrial age reached its inevitable end.

My largest Para grass patch after a minimal spraying that gave a 70-80% kill rate. I will spot spray shortly once the weather is warm enough to cause active growth.

A section of orchard that was dense Setaria grass monoculture a few years ago. Now that fruit and support trees are established and the understory is diverse the few remaining Setaria plants aren’t a major issue. I am hopeful the kid goats can become a yearly factor impacting weeds in the orchards but need to do extra experiments to figure out the details.

Tithonia shrubs in the orchard after cutting back. Once the stumps resprout they will be sprayed to finish them off. The kid goats were great company while cutting down but will be moved elsewhere before spraying begins.