Rise of the Superweeds

One of the arguments against GMOs has been that they caused the evolution of so-called “superweeds”, an epidemic that apparently has the world headed for a crisis. Some claim that we will soon be unable to sustain our modern agriculture techniques, and GMOs are at fault.

Fortunately, the reality is quite different. Superweeds are indeed a problem, and their evolution is causing significant problems for farmers. However, we do have options to control them, and emerging technology is going to help us out.

Superweeds – What Are They?

Superweeds really aren’t that super. They aren’t bigger, faster growing, or more competitive than “normal” weeds. All a superweed actually is is a weed that is resistant to a certain type of control. Becoming resistant to Roundup (glyphosate) doesn’t automatically make a weed more competitive, it just makes it more difficult for us to control them. It eliminates one of the tools we have in our toolbox.

Palmer amaranth is one of the most prolific glyphosate resistant weeds in the US, producing up to a million seeds per plant. (Superior Ag Resources photo/Tom Sinnot)

A common misconception is that superweeds are only resistant to glyphosate, but that is actually not accurate. Weeds have been evolving resistance to many kinds of control for as long as agriculture has been around. In fact, in India, farmers used to hand weed barnyard grass out of rice. Barnyard grass was very similar in appearance to rice, but it had a distinctive red stem. As farmers removed those weeds year after year, a different strain of barnyard grass with a green stem became more prevalent. Eventually, farmers could no longer tell the difference between barnyard grass and rice; they had selected for green stems (read more here). Essentially, you could call that particular strain of barnyard grass a superweed. 

What Causes Superweeds to Develop?

Like the example of the red-stemmed barnyard grass, evolution of resistance to glyphosate and other chemicals is really rather simple. Continuous application of the same chemistry to the same fields year after year will allow that one weed with natural resistance to proliferate. One year, there’s one of them. That weed produces dozens or – believe it or not – millions of offspring. In year two, depending on how many germinate, survive and reproduce, an exponential increase in resistant populations begins.

All that particular weed has is a mutation that allows it to survive the chemical. Lentil harvestSometimes, it can only survive a lower rate, which is why proper application rates are
so important. As that weed begins to spread, it finds its way into other fields and other farms. Combines do a great job of blasting weed seeds hundreds of feet through the air, and with the right wind, weed seeds can even be blown into adjacent fields.

Whose Fault Is It?

Are farmers to blame for this? In a word, yes. We are responsible for understanding the chemicals we apply on our own fields. Don’t get me wrong; I’m not trying to throw myself and my colleagues under a bus here. But there have been many farmers that simply grew Roundup Ready crops over and over for over a decade – applying incredible selection pressure to their weeds. Could pesticide companies do more to educate farmers on this subject? Yes, but they have vastly improved their education efforts. A fantastic example is Bayer Crop Science’s Mix It Up campaign, which informs farmers how their products can improve resistance management (read more here). I think the key going forward is that assigning blame gets us nowhere. Let’s instead focus on solutions.

When Roundup was first released, it was a novel herbicide that was considered to have “Low” susceptibility to resistance. Because of its mode of action, weeds would have to develop a complex resistance mechanism. Sadly, this assumption led to an overapplication of glyphosate, much of it at rates too low to be totally effective, and has thereby resulted in the loss of one of the great inventions of the modern age to many regions.

How Do GMOs Fit In?

The introduction of Roundup Ready crops in the 1990’s caused a surge in the use of glyphosate. It was cheap, safe, very effective on weeds and easy to apply. Despite what has been coming out in the media about glyphosate lately (read more here), it is actually a very safe product with no known health effects in humans or animals. It was a breakthrough in agriculture, one of the greatest of our time. It is because of this that its overuse was simply inevitable.

Nikon J1 205
A young GM canola crop with developing weed competition.

It is, however, important to distinguish that although Roundup Ready crops contributed to the overuse of glyphosate, they did not cause resistance themselves. Glyphosate is not the only product with resistance problems. Other chemical groups also have issues, such as sulfonylureas, imidazolinones, PPO inhibitors, plant growth regulators and so on have all led to the proliferation of their own resistant weeds. None of these products are tied to glyphosate resistant crops. In fact, even insects and plant diseases have evolved pesticide resistance. In Europe, for example, flea beetles have become resistant to pyrethroid insecticides. Canada thistle became a problem in the prairies largely because of cultivation, which allowed their roots to be spread all over the fields.

Any type of pest control can and will cause pest resistance if the selection pressure is high enough. Unfortunately for RR crops in the United States, the selection pressure was simply too high.

What Are We Doing About It?

Every problem has a solution, and superweeds are no different. The way to fix this problem is actually pretty simple – rotation. Using a variety of crops combined with a variety of chemicals prevents weeds from building resistance. Take that Roundup-resistant weed and hit it with something else. Maybe a different chemical, maybe a little bit of strategic tillage, maybe even just a more competitive crop.

There are some incredibly exciting developments in the world of crop protection. RNA interference technology may just be the new frontier in weed management. Palmer amaranth, a particularly problematic weed in the US, resists glyphosate by producing extra copies of EPSPS, an enzyme required for amino acid synthesis that glyphosate binds to and prevents growth, eventually causing death. It overcomes the glyphosate application by simply producing so many copies of EPSPS enzyme that it overwhelms the glyphosate molecules. To stop this from happening, RNAi prevents the production of the EPSPS enzyme. With less of it produced, glyphosate is once again effective (read more here and here).

While RNAi is very new and is probably years away from production, it is promising to see innovations like this on the horizon. In Australia, where weed resistance is a major problem, some farmers are using the Harrington Seed Destructor to destroy weeds as they leave the back of the combine, which is proving to be incredible effective. Robotic weed destroyers are prototypes today, but could be a game changer in the near future. But in the meantime, we must protect what we have. Careful rotations and proper application techniques will go far to secure the usefulness of the chemicals we have for the foreseeable future.

Superweeds are nothing new. Weeds always have and always will evolve survival mechanisms against our strategies to control them. GMOs are not the culprit here; a lack of discipline in the use of our most valuable chemistries is the reason we are having the problems we are having. Panic by local governments and knee-jerk reactions will not help us deal with weed resistance. Education, research and new ideas are what we need to combat this problem. Weeds have always been one of farmers’ greatest challenges, and we will have to continue to be innovative and determined to stay ahead of them.

Do We Really Need Chemicals to Control Weeds?

With seeding only a mere two weeks away (ish), every farmer’s mind whirls a million miles a minute in a thousand different directions. Do I have all my seed? Did I order enough fertilizer? When will I get into the field? Is my equipment ready to go? What chemicals am I using? And this is only scratching the surface. With seeding creeping up all too quickly, focusing on one thing at a time is vital to keeping your sanity and to ensuring you have all your bases covered. Right now, I’m concentrating on what may be the most important factor in the entire growing season: controlling weeds.

That may sound a little boring, focusing on a task that has been done for thousands of years. But if you cannot keep weeds under control, the crop will simply not be successful. Moreover, controlling weeds is a complicated and frustrating task.

I will admit, when I first graduated from university in 2010, I thought weeds were easy. Just throw in some herbicides and take care of ’em! Since then, I have learned that nothing Nikon J1 251about weeds is simple. On our farm, we use herbicides as the primary tool in controlling weeds. Of course, other cultural practices are important, such as rotating crops so that no crop is planted in the same field two years in a row (3-4 years between is better), using good quality, clean seed that emerges vigorously, seeding as early as we can to give our crops a head start, ensuring the drill doesn’t have any misses or blocked rows to get the ground covered as quickly as possible, and growing competitive crops that crowd out the weeds wherever possible. Yet, the only reason these practices all work is because of the use of herbicides.

Years ago, when my father was a child, farming was very different. Herbicides were more or less non-existent, except for the old standard: 2,4-D. However, it was so expensive to use that it was really only used for patch treatments to clean up problem areas. Instead of herbicides, the main source of weed control was tillage. Ripping the ground up and leaving it black was a summer-long job for many farmers, with half the farm in this “summerfallow” and half of it seeded to crops like wheat and barley. While this practice did work to control weeds, it was very hard on the soil, causing topsoil to erode from wind and water, and microorganisms in the soil struggled to survive. The famous “Dust Bowl” of the 1930’s was largely caused by tillage. But it was all they had to control weeds; without which, agriculture was doomed.

Source: www.hgis.usask.ca
Source: http://www.hgis.usask.ca

Everything changed with the advent of glyphosate, or “Roundup”, in the 1970s. This broad-spectrum herbicide changed the world, with its ability to control dozens of weeds at relatively low doses. While it was initially used sparingly due to its high cost, as the price came down, farmers were finally able to move away from tillage and use chemicals to control weeds instead.

I realize this is a tough issue for many of you non-farmers out there. Why do we use herbicides at all? Well, the alternative is organic farming, which does not use herbicides,

Source: www.real-debt-elimination.com
Source: http://www.real-debt-elimination.com

but instead uses tillage. Please recognize that the advent of all of our herbicides in the 1980s and 1990s is the reason we are able to practice no-till, which has saved our soils in Western Canada. We rarely have to till at all anymore, which protects our fragile topsoil from the ravages of high winds and heavy rainfall. Is their a resource more precious on this Earth than our soil? Moreover, the herbicides we use are largely safe (yes, even 2,4-D) and, as long as used as directed, have never caused any known injury even to we farmers applying them.

Certainly, herbicides do have their issues. Some were shown to be toxic, but they were removed from sale years ago. All of the herbicides we use are constantly monitored and must go through stringent safety and environmental testing before they are released for

Source: www.purdue.edu
Source: http://www.purdue.edu

use. Another issue with herbicides that has cropped up in recent years is weeds’ ability to adapt to them. Unfortunately, many farmers choose to grow the same crops over and over again on the same field, using the same herbicides multiple times per year. A random weed just may happen to have a genetic mutation that allows it to survive the application. That weed survives, spreads its seeds, and grows to a larger population the next year. This can quickly spread over an entire field, or more, in just a few years. Glyphosate, one of the world’s greatest discoveries, has become ineffective in many areas because of this.

Herbicide resistance isn’t the fault of the company that produces it. Sure, they could have done a better job of explaining to farmers the risk of overapplication. The onus, however, is on the farmer. It is his/her land and that farmer should have thought about the risk of growing the same cropping system over and over again. It is an unfortunate situation.

Because of the risk of resistance, we use a lot of different herbicides on our farm. There are 20140411_164107many different “groups” of herbicides that affect plants in different ways. For example,
2,4-D is a Group 4, which basically causes the plant to grow itself to death. Grasses generally aren’t affected by it, so it can be used on crops like wheat and barley. Using this group over and over on the same field can result in the weeds adapting to it, so we rotate Group 4s with other groups, like Group 2, 6, 27 and some others. This takes careful management, but it is very effective.

Some herbicides are sprayed on top of the crop, while some are sprayed on the soil before seeding, and still others are dry products mixed into the soil in the fall before seeding. All have their fit, and using the right mixture can kill the weeds your specific fields have difficulties with.

Nikon J1 210Mother Nature has an incredible ability to adapt to whatever we throw at her, and controlling weeds is somewhat of a treadmill; every time we come up with a new way to kill them, they come up with a way to survive it. Frustratingly, they seem to slowly be winning the war, with herbicide resistance popping up more and more every year.


So, every spring I go through the hundreds of different products that are out there to try and determine which ones I will use that year. As I learn more and more about weeds and Nikon J1 230herbicides, I learn better ways to control them, especially the ones that plague our area, like kochia, wild oats, foxtail barley, stinkweed, Canada thistle, wild buckwheat, and many, many others. Weeds are crafty plants that always seem to find a way to overcome every hurdle you throw at it; but if we challenge them every year with different crops, different herbicides, and different ideas, we can beat them. Agriculture is all about problem solving, and coming up with new and innovative ways to reinvent the wheel. Never stop thinking and never stop learning, and you just may have a shot at making a go of this thing we call farming.

What do you think about herbicides? Should we be using them, or should we go back to tillage? Write your comments below!


Seeding Progresses…

It is 10:45 at night and I have just had supper, so I will make this short. Seeding is progressing fairly well, with the half-way point at hand. Tomorrow we will cross the half-way mark of the 2013 seeding season after a little more than a week of seeding. This progress is impressive, but we actually were a little faster last year, so I cannot help but feel that we can do better. Tomorrow we will finish our soybeans, and the day after our peas will also be completed. If things continue at the rate they are currently progressing, by early next week we should have our canola completed as well, leaving only the remaining durum acres and our spring wheat.

If you would have asked me 3 weeks ago if I thought we would be half-done by the 22nd of May, I would have laughed. 3 weeks ago, the ground was still white! Today, unbelievably, we are wishing for rain. What we have seeded is quite dry now, and most of our crop has yet to show its face. Every day seems to be warm, dry, and windy, which we were once happy about, but are now beginning to become concerned. We did get a rain on Monday, but unfortunately the ground we have seeded basically missed it. Ironically, the only fields that did get a significant amount of rain are fields that are not seeded yet.

The wind is becoming frustrating not only because of its drying effect on the soil (and on ourselves!) but because it is seriously disrupting our spraying. Generally, you must spray a field before or immediately after you seed it to take care of weeds before your crop comes up. Weeds can have a devastating effect on the success of your crop; and for some uncompetitive crops with limited chemical options, like peas and lentils, they can literally wipe a crop out. Therefore, completing spraying pre-emergence (called “burn-off”) is vital to the success of the growing season. Very windy days keep the sprayer parked because the spray simply will be blown away before it reaches the ground. Too many days like this in a row can really disrupt our ability to stay ahead of the crops (and the weeds).

Still, we are keeping up (barely) and we may be able to more or less finish seeding within the first week of June. This would be nothing short of outstanding progress, considering the very late start. Indeed, it may have been our latest start ever, and we will be able to finish seeding at quite an average time of the year. This is, of course, assuming there are no major breakdowns and no major rain events. Hopefully we do get some rain, though, or our best efforts of getting the crop in quickly will be in vain. Waiting for that first rain is always very stressful. A lot of money has been planted in the ground, and it could all go to waste simply by missing a couple of key rains.

But enough of that worry for tonight. The goal right now is to get the crop in and get it sprayed with as few mistakes as possible. This may seem like a bit of an oxymoron, as the harder you go, the less sleep you get, and the less sleep you get, the more mistakes you make. But this is a fact of life of Prairie dryland farming.

Tomorrow we will try to post some big acres and get our soybeans planted. Wish us luck!