Seek and Destroy: The Control Of Herbicide-Resistant Weeds Through Seed Destruction

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Speed of chaff movement is critical for the system to work best. (Photo: Dr. Neil Harker)

According to Breanne Tidemann, a field agronomy scientist with Agriculture and Agri-Food Canada based in Lacombe, Alta., herbicide resistance is continuing to increase in terms of how common it is, as well as how challenging it is to manage.

“With each new herbicide-resistant weed, herbicide options become more restricted. With wild oat as an example, we have biotypes on the Prairies resistant to group 1 and 2 herbicides quite commonly, but there is also resistance to group 8, 14 and 15 products. That really limits herbicide options,” she says.

Tidemann and her colleagues have been exploring other avenues of control, chiefly a machine designed to destroy weed seed at harvest. Funding for the research, which started in 2017, is being provided by the Alberta Canola Producers Commission, Alberta Wheat Commission, Saskatchewan Wheat Development Commission and the Western Grains Research Foundation.

“In my opinion, the answer to herbicide resistance isn’t another jug of chemical,” she says. “We need to use multiple methods of managing weeds, and to me, it only makes sense to start targeting the seeds. Why let surviving weeds — the ones most likely to have new resistance traits — put their seeds into the seed bank to be a problem next year? I think seed destruction could play a key role in managing herbicide-resistant weeds in the, hopefully, near future.”

Ian Epp agrees. He says in addition to reducing the total number of weed seeds entering the weed seed bank, harvest seed management is also beneficial in reducing the spread of weed species, including herbicide-resistant weeds, within a field. “Combines represent one of the best dispersal mechanisms available to weeds,” says the Saskatchewan-based agronomy specialist with the Canola Council of Canada.

“Seeds that enter the combine may be spread up to several hundred feet away from the initial mother plant, which for patchy weeds, or seeds from a newly-introduced herbicide-resistant biotype, represents an efficient method of establishing new patches and rapidly becoming a widespread field problem.”

This may result, he says, in growers using otherwise too expensive or intensive ‘patch’ management strategies to deal with, or delay, a weed problem. He firmly believes that reducing the number of seeds entering the seed bank, and/or manipulating where they enter the seed bank, are two important tools for managing an ever-changing composition of weeds in any field.

Current Research

In 2017 and 2018, Tidemann and her team experimented with seed destruction in 20 producer fields in Alberta, and the trials will continue for two more years to determine the effects of this technique on surviving populations. “We took weed counts this spring, but that data isn’t summarized yet.”

She’s using the Harrington Seed Destructor (HSD), invented in Australia, a device that’s towed behind the combine and features a cage mill that crushes the chaff — and the weed seeds the chaff contains. Speed of chaff movement is critical for the system to work best, and Tidemann has also found that farmers should wait until green or tough material has had a chance to do some drying.

The tow-behind HSD model is actually no longer on the market, but the firm offers the Integrated Harrington Seed Destructor (iHSD) that mounts directly onto the combine. Australian researchers have shown that the HSD and iHSD provide similar results. There is also a competitor called the Seed Terminator.

As far as Tidemann is aware, there are no published research results about the performance of the iHSD or its competitor, but she says a number of producers are using the iHSD in Australia, and there is also one being used in Canada, north of Saskatoon. She’s heard that both of the mill systems on that unit ran into some wear issues last harvest, and that some modifications are being tried.

Mechanics of Destruction

In order for a seed destruction system to be effective, the weed seeds obviously need to be in the chaff. Cleavers and volunteer canola work well, but chickweed seed doesn’t because it’s so close to the ground and producers don’t want to chance equipment damage by cutting at that level. Tumble weed also presents a similar issue — as does wild oat, but for a different reason.

During Tidemann’s PhD studies, she found that wild oat seems to shed its seed prior to crop harvest. “So, what we did is we compared early-maturing crops (peas followed by winter wheat) to ‘normal’ maturity crops (wheat and canola) to late-maturing crops (faba bean and flax),” she says. “We collected chaff off the plots when we harvested and counted how many wild oats we collected in each plot (which would be the ones to go through something like an HSD). We also compared swathing and straight cutting in each of those rotations. The idea was that we should collect the most wild oats in early-maturing crops, and should collect more by swathing versus straight cutting.”

Preliminary results show that more wild oat seeds are collected when crops are swathed, but Tidemann says more are not necessarily collected with earlier-maturing crops. “We still have to do a final analysis on this data to see if those preliminary results are true at all sites and years, and then we need to try and figure out why,” she says. “It’s possible that wild oats are more variable than we suspected, which makes it harder to manipulate agronomics to collect more seeds. More to come on this project in the next year or so.”

Tidemann notes that a couple of producers in the province are trialing a harvest weed seed control method called chaff lining (see sidebar) that’s less expensive than seed destructors. At this point, she doesn’t think most producers see the cost of seed destructor systems being worthwhile.Epp reports that the iHSD currently costs about $150,000 and the Seed Terminator rings in at about $100,000. However, while Tidemann states that something like chaff lining may be easier to adopt initially, a lot of the same operational principles apply in terms of, for example, seed capture/retention issues.

In terms of when seed smashers might be used on a widespread basis, Tidemann says that at least two other factors are at play besides cost of the equipment, including her research results and the rate of spread of herbicide resistance. “I hope over the next few years we start seeing interested producers. I hope to do some more exploration into what’s going on with wild oat seed retention, and also look forward to trialing something like chaff lining.”

An enjoyable part of Tidemann’s work is seeing producers get interested in ways of solving problems like weed control. “They have so many ideas and so many different perspectives about what will work on their farm and why,” she says. “I love hearing from them and hearing what they’re thinking about trying.”

Another Look: Chaff Lining Research in Australia

Chaff lining is the practice of concentrating chaff in a narrow row between stubble rows directly behind the harvester. An August 2018 University of Western Australia report states that use of chaff lining has risen rapidly in that country over the last two years. “A survey of WeedSmart subscribers,” states the report, “shows the percentage of growers using chaff lining increased from 6% in 2016 to 26% in 2017.”WeedSmart is an industry-led initiative to enhance on-farm practices and promote the long-term sustainability of herbicide use.

Recent studiesheaded by Annie Ruttledge, from the Department of Agriculture and Fisheries in Toowoomba, Australia, show that use of chaff lining or chaff tramlining — when chaff material is concentrated on dedicated tramlines in controlled traffic farming systems — does concentrate weed seeds into a narrow area, and that heavy layers of chaff lead to better suppression of weed emergence.

“Small seeded broadleaf weeds, for example common sow thistle, are more easily suppressed than grass weeds with larger seeds, such as annual ryegrass. Thick tramlines and chaff lines reduce, but do not prevent, weed emergence, so other measures may be needed to control weeds in tramlines/chaff lines, for example, spraying the tramlines with a shielded sprayer,” says Ruttledge.

For more information go to https://weedsmart.org.au/how-chaff-lining-works/and https://ahri.uwa.edu.au/chaff-liningtoo-good-to-be-true/.

Ag robot speeds data collection, analyses of crops as they grow

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University of Illinois agricultural and biological engineering professor Girish Chowdhary is leading a team that includes crop scientists, computer scientists and engineers in developing TerraSentia, a crop phenotyping robot. (Photo: L. Brian Stauffer)

A new lightweight, low-cost agricultural robot could transform data collection and field scouting for agronomists, seed companies and farmers.

The TerraSentia crop phenotyping robot, developed by a team of scientists at the University of Illinois (U of I), will be featured at the 2018 Energy Innovation Summit Technology Showcase in National Harbor, Maryland, on March 14.

Traveling autonomously between crop rows, the robot measures the traits of individual plants using a variety of sensors, including cameras, transmitting the data in real time to the operator’s phone or laptop computer. A custom app and tablet computer that come with the robot enable the operator to steer the robot using virtual reality and GPS.

TerraSentia is customizable and teachable, according to the researchers, who currently are developing machine-learning algorithms to “teach” the robot to detect and identify common diseases, and to measure a growing variety of traits, such as plant and corn ear height, leaf area index and biomass.

“These robots will fundamentally change the way people are collecting and utilizing data from their fields,” said U of I agricultural and biological engineering professor Girish Chowdhary. He is leading a team of students, engineers and postdoctoral researchers in development of the robot.

At 24 pounds, TerraSentia is so lightweight that it can roll over young plants without damaging them. The 13-inch-wide robot is also compact and portable: An agronomist could easily toss it on a truck seat or in a car trunk to transport it to the field, Chowdhary said.

Automating data collection and analytics has the potential to improve the breeding pipeline by unlocking the mysteries of why plant varieties respond in very different ways to environmental conditions, said U. of I. plant biology professor Carl Bernacchi, one of the scientists collaborating on the project.

Data collected by the crop-scouting robot could help plant breeders identify the genetic lineages likely to produce the best quality and highest yields in specific locations, Bernacchi said.

He and Stephen P. Long, a Stanley O. Ikenberry Endowed Chair and the Gutgsell Endowed University Professor of Crop Sciences and Plant Biology at Illinois, helped determine which plant characteristics were important for the robot to measure.

“It will be transformative for growers to be able to measure every single plant in the field in a short period of time,” Bernacchi said. “Crop breeders may want to grow thousands of different genotypes, all slightly different from one another, and measure each plant quickly. That’s not possible right now unless you have an army of people – and that costs a lot of time and money and is a very subjective process.

“A robot or swarm of robots could go into a field and do the same types of things that people are doing manually right now, but in a much more objective, faster and less expensive way,” Bernacchi said.

TerraSentia fills “a big gap in the current agricultural equipment market” between massive machinery that cultivates or sprays many acres quickly and human workers who can perform tasks requiring precision but move much more slowly, Chowdhary said.

“There’s a big market for these robots not only in the U.S., where agriculture is a profitable business, but also in developing countries such as Brazil and India, where subsistence farmers struggle with extreme weather conditions such as monsoons and harsh sunlight, along with weeds and pests,” Chowdhary said.

As part of a phased introduction process, several major seed companies, large U.S. universities and overseas partners are field testing 20 of the TerraSentia robots this spring through an early adopter program. Chowdhary said the robot is expected to become available to farmers in about three years, with some models costing less than $5,000.

The robot is being made available to crop scientists and commercial crop breeders for the 2018 breeding season through EarthSense Inc., a startup company that Chowdhary co-founded with Chinmay P. Soman.

A former National Science Foundation postdoctoral fellow at the university, Soman is the chief executive officer of EarthSense, which is based at the U of I Research Park and comprises a growing team of engineers and computer scientists.

Source: University of Illinois at Urbana–Champaign

Becoming One with the Machine

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The DOT Power Platform is designed to handle a large variety of implements commonly used in agriculture.

This new seeding innovation is one example of how new ideas are transforming precision ag.

Agriculture – like all other sectors – is changing fast, with new technologies and computing power now being employed to achieve things our grandparents wouldn’t believe. One example of these achievements is precision agriculture, and Saskatchewan-based SeedMaster has taken precision ag a step further on its evolutionary path by developing the DOT Power Platform.

The DOT Power Platform is designed to handle a large variety of implements commonly used in agriculture, mining and construction. Its U-shaped frame directly loads implements so that they ‘become one’ with the machine. It can be run by remote control or in completely autonomous mode.

DOT is the brainchild of SeedMaster founder Norbert Beaujot, and it’s one of a long line of innovations Beaujot has dreamed up and brought to reality over his long career. Both his background in farming and his education as an agricultural engineer at the University of Saskatchewan prepared him for this calling.

“As a company, we’re always striving for more efficiencies and profitability at the farm level, and on that continuous quest, we’ve developed quite a few pieces of equipment,” Beaujot explains. “We’ve grown in precision ag, in metering and everything else seeding related. We were the first to build an 80-foot and then a 100-foot seeder, both with high capabilities in metering and other areas of operation.”

Indeed, it was thinking about larger equipment that led Beaujot to come up with DOT.

“I was thinking, how do we regain efficiencies that we lost in going bigger?” he recalls. “It was an evolution of thoughts about this in the beginning. Of course, we’re always hearing about autonomous cars and autonomous buses in the media, which also got me thinking about autonomous agriculture. From having the idea, it was a series of sketches and brainstorming various designs, looking at how one unit can power all the different implements.”

For most of the next two years, Beaujot worked out all the details, everything from how to mount the steering and wheels to where the engine should sit.

“I didn’t want a traditional tractor design of course. The U-shape means DOT can drive ‘into’ any implement made to receive it, and you just have to attach hydraulic hoses and electrical, but someday that might be automatic as well.”

After the U-shape came to him as the best design, the other components had to be fitted, but he’s always really looking for a simple way of doing things, he explains. “I filed the patents pretty early on and to file, you have to work out a lot of details and provide sketches.”

Beaujot decided to place the engine and some other things on one of the side rails, making it possible for tanks and other things to be placed on the other side, and for seeding and tillage equipment to go below the rails. Then he had to scale the unit correctly for efficient operation on large farms.

In terms of autonomous operation on-farm, the first step is to load boundary and field obstacle information into the system. A few seconds later, the DOT software creates a path plan, which is then approved by the farmer and can be altered at any time to address changing field conditions. During actual operation, DOT’s short- and long-range sensors allow it to sense any issues in its path, and if it’s unsure how to proceed, it will send an alert to its farmer-owner.

A prototype DOT unit is busy powering a seeder, sprayer, land roller and grain cart on research fields. In 2018, there will be a limited release of DOT to select farms in Saskatchewan, followed by broader distribution nationally and beyond in due course. Since its launch at the Ag in Motion show in Saskatchewan in July of 2017, it’s not surprising that DOT has received a groundswell of interest inside and outside of agriculture from around the world.

Norbert’s son and DOT marketing and sales manager Cory Beaujot believes the seed-growing industry would benefit from the DOT model of autonomous agriculture in several ways.

“Pre-plotted-out maps of seeded areas dedicated to this variety or that and safe and easy transition between different varieties, are a couple of things that come to me right away,” he says.

Norbert adds: “The way DOT keeps track of everything — the day, weather, plot size, GPS coordinates and so on — it makes it easy for farmers to keep historical records and for researchers to replicate trials. Whether it’s a seed grower or non-seed-growing farmer, they don’t want to lose anything, don’t want to damage seed or waste anything, and DOT also assists with that.”

The Future

Cory notes that food security is of ultimate concern to a huge percentage of the world’s population today and that it’s only going to become more important as we march forward.

“Various aspects of food security are beyond our control — climate, weather patterns, to a lesser degree global politics and so on,” he says. “That said, things like crop genetics, efficiency-enhanced shifts in the food production and distribution systems are under our control. This is where SeedMaster and DOT step in. If we don’t think out of the box, we’re more likely to replicate the inefficiencies of the past. Out-of-the-box thinking shakes things up, ruffles feathers, creates dialogues and leads to innovation and positive change.”

The absence of a good labour source for farms, Norbert adds, is another reason agriculture is going to continue to need innovative thinking.

Canadian futurist Richard Worzel agrees. He believes precision ag systems will become more prevalent because there will be fewer people willing or able to become farmers, and Canada will need more systems that both cut down on labour and increase productivity. He notes that “software programs that can watch for you and alert you, can come up with quantitative analysis based on in-depth analysis of massive amounts of data. DOT combines some of that and these systems will only get more common.”

While he notes systems like DOT are innovative, they’re not a true form of artificial intelligence. Worzel foresee a possible future where farms may have a true AI that a sub-system like DOT reports to when it runs into a problem, instead of reporting to a human being.

As for how he achieves his out-of-the-box thinking, Norbert gives much of the credit to his ability to simply dwell on a problem.

“In the first two years, there were very few days I didn’t think about it, some days three hours and some days 11 hours,” he says. “A lot of people would get bored. I don’t consider myself smart beyond the average, but I have the ability to focus intensely on a mechanical problem and come up with solutions.”

He adds: “I’ve read that Einstein would think and think and not get very far and go fishing and it would be there. So sometimes taking a break really works well. But when the subconscious mind comes up with something that seems complex, I’ve found it’s really a bunch of simple thoughts that come together.”