A research scientist at Agriculture and Agri-Food Canada in P.E.I is investigating natural ways to deal with pests that damage cabbage, canola and potatoes. 
Published in Insect Pests
Lawrence MacAulay, minister of Agriculture and Agri-Food, announced an investment of up to $6.3 million in funding to the Western Grains Foundation for a five-year Integrated Crop Agronomy cluster that will focus on agronomy research into multi-crop and integrated crop production.
Published in Corporate News
Green seed in canola is a downgrading factor that causes more than $150 million in losses annually. But researchers at the University of Calgary hope to help reduce those losses with the identification of a gene that helps the de-greening process.
Published in Canola
Nitrogen (N) fertilizer management continues to be a priority for farmers and researchers, with a large research focus on the effect of N management in the year of implementation. However, researchers also want to understand the longer-term implications of N fertilizer strategies and decisions in a cropping system.
Published in Canola
The impacts of clubroot on susceptible canola cultivars are usually pretty obvious – the plants look drought-stricken and have large, irregular swellings (galls) on their roots. But the pathogen itself has remained somewhat enigmatic. Now a team of researchers mostly from Western Canada, led by Hossein Borhan and in collaboration with scientists from England and Poland, has sequenced the clubroot genome. This work is generating insights into the pathogen and how it functions, and is providing a springboard for future advances in clubroot management.
Published in Agronomy
Presented by Franck Dayan, professor, department of bioagricultural sciences and pest management, Colorado State University, at the Herbicide Resistance Summit, Saskatoon, Feb 27-28, 2018.

Group 14 herbicides are part of a group of chemistries that require light to be effective as an herbicide. In Canada, one of these compounds is called Heat (saflufenacil), and is a protoporphyrinogen oxidase (PPO-inhibiting) herbicide. There are other light-dependent herbicides, as well. Photosystem II (PS II) is a chemistry that interferes with photosynthesis and disrupts plant growth. An example would be AAtrex (atrazine) (Group 5). There’s also inhibitors of PS I, another part of photosynthesis, including compounds like Gramoxone (paraquat) (Group 22). These two chemistries are related and affect the transfer of electrons within photosynthesis.

Plants also need chlorophyll and carotenoids for photosynthesis to occur, and there are compounds that are inhibitors of PDS like Solicam (norfluzaron) (Group 12). Another compound inhibits one of the precursors to the carotenoid pathway such as Command (clomazone) (Group 13). Some of the new chemistries, the HPPD inhibitors like Callisto (mesotrione) (Group 27), are also part of this class of chemistries. All of these are called light-dependent herbicides because they affect one aspect or another of photosynthesis, either through the transfer of electrons or the synthesis of the pigments, and require light to be active.

Dayan slide 3 Overview of light dependent herbicidesI’ll be talking about PPO inhibitors, an enzyme that is involved in porphyrin and chlorophyll synthesis. Why do we care about these compounds? When they work they work really, really well. PPO-inhibiting herbicides were first commercialized in the 1960s and their market share in the U.S. reached about 10 per cent in the late 1990s. A lot of herbicides have been synthesized that target this enzyme or pathway. About 100,000 compounds may have been synthesized that can inhibit this enzyme. Of course not all of them make it to be an herbicide.
These PPO-inhibiting herbicides were initially used mostly as post-emergent, broad-spectrum weed control in soybean fields. That’s how they were primarily used for the longest time. Some like carfentrazone (Aim in Canada) were developed for cereal crops. Some were so active that they were used as non-selective herbicides.

Mode of action

When the herbicide is applied, it lands on the leaf surface and then goes through the top layer, called the cuticle. It goes through the epidermis, and then has to get to the target site. There it inhibits an enzyme that produces a compound called Proto IX. Proto IX is supposed to be in the chloroplast, but when you apply the herbicide, Proto IX accumulates outside of the chloroplast. When the sun comes out, Proto IX reacts with sunlight, what’s called reactive oxygen degradation, and basically destroys the cell structure of the plant. Within a few hours the plant dries up. It becomes paper-thin and completely dehydrates. Injuries like leaf cupping, crinkling, and bronzing appear on some plants, and then typically necrosis and completely dead tissue within a few hours. It’s a pretty fast-acting herbicide, and it works really well under the right circumstances.

Some plants are very sensitive because they can’t metabolize the herbicide. Some plants are very tolerant because they metabolize the herbicide very quickly. Since some plants can metabolize it very quickly, a plant can become resistant by developing the ability to metabolize this chemistry, which would be non-target site resistance.

Most PPO inhibitors degrade very quickly in the environment. Most compounds have a very short half-life and have very poor pre-emergence activity. However, a compound like sulfentrazone (Authority; Authority Charge) can have a very long half-life, 280 days. In the south US that may actually affect rotation of your crops because of the long residual activity of some of that chemistry.

[Ed. Note: In Canada, carfentrazone has a short half-life and when used as a pre-seed treatment, there are no cropping restrictions. Sulfentrazone’s longer half-life means it can be used as a pre-seed surface application that provides residual weed control, but also means there are re-cropping restrictions.]

The PPO inhibitors are very rapidly metabolized and don’t stick around in water. They’re considered to be a pretty safe chemistry.

A resurgence in use 

There used to be a lot of use of the PPO chemistries in the 1990s. In 1996, the first Roundup Ready crops were introduced and their use dramatically decreased. Where PPOs were used extensively for weed control in soybean, it was replaced by glyphosate. But the use has picked up again because of glyphosate resistant weeds. It is a great tool to manage glyphosate resistant weeds in the south and the Midwest as well. In Canada it might be a good tool in the future as you see more and more glyphosate resistant weeds.

Chart: Use of PPO inhibitors
Use of PPO inhibitors by year and crop
Some plants have become resistant to PPO chemistry. For most of them we don’t know the mechanism. But for waterhemp, Palmer amaranth, and ragweed, we know there have been mutations on the target site gene. That’s similar to what happens with ALS inhibitors and ACCase inhibitors. That’s what happens with some glyphosate resistance in some cases.

At the target site, there are two genes that make two proteins. One goes to the chloroplast; one goes to the mitochondria. When the plant became resistant, many scientists sequenced the gene for the protein that goes to the chloroplast because that’s where the herbicide works by preventing chlorophyll synthesis. However, no mutation was found at that location. Dr. Tranel at the University of Illinois sequenced the other gene that goes to the mitochondria. He found that there was a mutation where a whole amino acid was removed, and that was kind of unusual. But there was also something added to the gene, and that was the first time this was reported to happen in plants.

This was very unusual. The herbicide is supposed to inhibit the chloroplast enzyme, but that little bit of DNA that was added to the sequence made the mitochondrial gene also go the chloroplast. So now you have a plant cell where a resistant trait is in both locations – the mitochondria and the chloroplast.

That’s important because these resistant plants now have the capacity to do the deletion and develop resistance, and have the capacity to move it to both locations. This has proven to be true in Palmer amaranth, water hemp, and ragweed. There’s no other herbicide so far that we know where plants have become resistant by this mechanism.

We looked at many genetic sequences to look for all the potential plants that have the same gene structure that could have a deletion. One of the plants is kochia. Kochia is a big weed in Colorado and in Canada. We now know that kochia is already predisposed to that mutation. If we keep using PPO chemistry the way we’ve been doing it and try to control kochia, most likely kochia will become resistant to that chemistry in exactly the same way that Palmer amaranth has become resistant. If you know a weed is predisposed to the mutation, then you should be scouting for weed escapes when you use that herbicide.

Now because you have resistance doesn’t mean you have resistance. What? Some interesting research was conducted by Peter Sikkema in Canada where fleabane escaped control by PPO chemistry. He demonstrated in the greenhouse that those seeds he collected in the field were resistant. What’s interesting is he went back the next year to the same field, applied the same herbicide and had 100 per cent control. An escape does not mean that your field is infested with the resistant weeds. In this case, it could be that the resistant weeds did not over-winter very well. So be on the lookout, but don’t freak out. If you have an escape it could be just something that’s a freak accident. But always be on the lookout for those escapes because we know that it can happen.

Management strategies

I’m not very familiar with the Canadian system, so suggested management strategies come from Arkansas where they deal with PPO resistance all the time in soybean. These may not necessarily be applicable to Canada. Use two active ingredients at planting, typically metribuzin (Group 5) and a Group 15 such as acetolachlor. Both are needed for successful residual activity. Then 21 days later use a post-application of glufosinate (Group 10), dicamba or 2,4-D (Group 4s) tank mixed with Dual (s-metolachlor; Group 15) for additional residual activity. In Arkansas, glyphosate is not useful because most major weeds including PPO resistant biotypes are already resistant to glyphosate. ALS herbicides are not useful in Arkansas either, as about 50 per cent of weeds have resistance to this group.

For more stories on this topic, check out Top Crop Manager's Focus On: Herbicide Resistance, the first in our digital edition series.
Published in Herbicides
Presented by Breanne Tidemann, Agriculture and Agri-Food Canada, Lacombe, Alta., at the Herbicide Resistance Summit, Feb 27-28, Saskatoon.

In order for harvest weed seed control (HWSC) to be effective, weed seeds still have to be retained on the plant at the time of harvest. If they’ve already dropped to the soil, they’re already in the seed bank. The weed seeds also need to be at a height where they can be collected by the combine. For example, chickweed is very low growing and its seeds are very low to the ground. Most producers don’t cut that low to the ground because of risk of damaging their equipment, so chickweed would not be a good candidate for harvest weed seed control.

Harvest weed seed control also means being able to get the weed into the combine. An example is a big tumbleweed, such as kochia. If the tumbleweed won’t feed into the combine and goes over top of the header, then you won’t be able to get the seeds into the combine for harvest weed seed control.

There are different methods of harvest weed seed control. Some of them have been scientifically evaluated in Australia. One of the most common methods is narrow windrow burning. The straw and chaff are dropped into windrows using metal chutes that are attached to the back of the combine. It’s cheap and easy to implement. But there are environmental impacts because it does involve burning. From a practical point of view, it may not work in western Canada, but it is used a lot in Australia.

windrower on a field at dusk
Chaff carts were originally developed in Canada. The Australians have modified Canadian chaff carts and use a conveyer system instead of a blower system to move the chaff to the cart. They’ve also adopted new technologies to make burning or collection easier and more efficient. Some of the chaff carts are programmed with GPS to dump the chaff in a certain area of the field to be grazed or burnt.

There was one Australian producer that commented he’s been using a chaff cart for 15 years, and about 10 years in he started seeing annual ryegrass that was much shorter, much lower to the ground and was dropping its seeds much earlier. So this is still a selection pressure. You will select for resistance to these methods if it’s what you’re relying on to control your populations.

chaff cart
The bale direct system bales chaff and straw directly behind the combine into a square bale. The square bales are removed from the field, taking the weed seeds with them. The loss of the residue from the field can be detrimental in terms of nutrients loss. And there is potential for transport of weed seeds in the bale from one region to another, potentially moving herbicide resistant weeds with the bale. The other issue in Australia is one producer started doing this and he saturated the entire market. The bales can also be pelletized to produce pelletized sheep feed, but again it’s a relatively small market. So market can be an issue with this methodology.

bale direct system
The Harrington Seed Destructor uses a cage mill to grind the chaff and weed seeds. The cage mill has two counter-rotating plates that spin very fast in the opposite directions. The weed seeds go in to the middle of the mill and have to move from the inside out to continue to move through the system. The straw moves along a conveyor belt and goes through a spreader at the back. Only the chaff is processed through the cage mill. The disadvantage is that the first model was towed behind the combine and required a lot of horsepower.

harrington seed destructor
The tow-behind model was always intended as step one. The Integrated Harrington Seed Destructor (iHSD) is mounted on the combine and uses the same cage mill system. The integrated model had several improvements. Instead of having the two counter-rotating plates there’s only one rotating plate and one stationary plate, but that rotating one turns twice as fast. It is a hydraulically driven machine and takes about 80 horsepowers from the combine to run this machine.

integrated harrington seed destructor
A new combine mounted seed impact implement was first announced January 2017. The Seed Terminator is competition to the Harrington Seed Destructor. It uses a slightly different type of mill called a multi-stage hammer mill, but it works on essentially the same idea of crushing or grinding those seeds so that they’re dead and can’t grow the next year. This is mechanically driven rather than hydraulically driven. In terms of price differences, the original tow behind Harrington Seed Destructor was about $200,000. The integrated Harrington Seed Destructor is somewhere around $150,000. The Seed Terminator is about $100,000. So what you’re seeing is as these competitors come to the market that price point is dropping, and we do expect that to continue.

Seed terminatorChaff deck or chaff tramlining works in a controlled traffic system. The idea is to put chaff on the permanent tramlines so if weeds grow there isn’t much impact on overall yield. The chaff in the tramline is also driven over multiple times, which can impair weed growth, and there is potential for seed decomposition in those tramlines. What farmers have seen is that there are fewer weeds growing in the tramlines, but it hasn’t been scientifically evaluated at this point.

chaff deck
Chaff lining can still be used outside of a controlled traffic system. The chaff is placed in a narrow row to decompose instead of spreading the seeds across the entire field. However, there is potential for some seeding or emergence issues if you’re seeding through this concentrated chaff row. It hasn’t been researched, but a lot of producers are adopting this in Australia as their first step in harvest weed seed control because it’s inexpensive and easy to implement.

The Australian experience

In Australia, a 2016 survey of 602 growers were asked about their adoption of narrow windrow burning, chaff carts, chaff tramlining, the bale direct, and the HSD. The Seed Terminator and integrated Harrington Seed Destructor were not released at the time so they don’t show up in the survey.

Across Australia 43 per cent of producers were using some method of harvest weed seed control. Narrow windrow burning was the most common. In Western Australia that number goes up to about 63 per cent. Western Australia is essentially where all of these methods were developed. Western Australia is really the epicentre because of herbicide resistance, and harvest weed seed control is spreading out from there.

The adoption of chaff tramlining this past harvest has skyrocketed. There is a lot more discussion about different systems on social media, and a lot more discussion about what works and what doesn’t work than we’ve see in past years. If that survey was to be redone I think we would see some of the tramlining and chaff lining skyrocketing.

Results from the same survey show that 82 per cent of producers said they expected to adopt some form of harvest weed seed control in the next five years with 46 per cent expecting to use narrow windrow burning. More producers would like to be using the iHSD, but they had concerns about the cost and the perception that it was unproven in terms of weed kill. The perception of unproven control of weed seeds is interesting because weed kill is where there is the most research.

Research has been done in Australia to show how effective harvest weed seed control was on controlling annual ryegrass populations in “focus paddocks” or “focus fields.” The research compared crop rotations where harvest weed seed control was used in 38 per cent of crops compared to rotations where it was only used in 11 per cent of crops. The ryegrass population was managed far more effectively where harvest weed seed control was used, and it has stayed very low.

Effects of HWSC in Australia:
Effect of HWSC in Australia
Photo courtesy of Michael Walsh.

Potential in Canada

In Western Canada we’ve believed that the physical impact implements that destroy seeds are most likely to have the best fit. They don’t require the burning, and it has some scientific testing behind it that shows it’s effective. So that’s where researchers have focused efforts in terms of testing a method for Western Canada.

We looked at the top 10 weeds in Saskatchewan and gave them a seed retention rating -- how well does the weed holds onto those seeds until harvest. A number of weeds are in the good or fair to good retention rating, and that’s promising. Green foxtail gets a good retention rating while buckwheat gets a fair to good. Volunteer canola is rated good. The unfortunate ones are the poors: wild oat, spiny annual sow thistle, narrow-leaved hawk’s-beard. Those have poor retention and are unlikely to be primary targets for harvest weed seed control because a lot of their seeds are already gone by harvest.

10weeds FocusOnHRLooking at some small plot experiments, seed retention of wild oat, cleavers, and volunteer canola was looked at. Volunteer canola retained most of its seed by the end of September, cleavers was intermediate and wild oat retained about 20 per cent of the seed by the end of September.

Kochia has good seed retention. Their seeds only mature after harvest, so most of the seed is still there at harvest, but the concern is that below the cutting height, typically six inches, there can still be over 5,000 seeds below that cutting height. So even though a lot of seed is collected by the combine, there could still be a lot missed and left in the field. At this point we aren’t sure what impact harvest weed seed control would have on kochia.

As part of my PhD research, we looked at running samples through the Harrington Seed Destructor in a stationary format set up in the shop. We mixed buckets of chaff with weed seeds and ran them through to determine how many are destroyed. We looked at five weed seed species: kochia, green foxtail, cleavers, volunteer canola, and wild oat. We put 10,000 seeds of each of those species into a five-gallon pail of chaff, put it into the Seed Destructor and assessed how many lived when they came out the other side.

A second study looked at weed seed size. Weed seed species are all different shapes, sizes and seed coat types. We took canola seeds and we hand sieved them to get thousand kernel weights between 2.2 grams per 1,000 and 5.8 grams per thousand.

We also looked at weed seed number by comparing 10 canola seeds up to a million canola seeds in the same volume of chaff. We also looked at chaff volume, so 10,000 canola seeds going through with no chaff or up to eight five-gallon pails of chaff in the same timeframe. And we also looked at chaff type, so barley, canola, and peas.

When we looked at weed seed species we did find significant differences in terms of control but our lowest level of control was still over 97 per cent killed. It worked really well on all the species that we tested.

In terms of canola seed size, we expected to see an increase in control as the size of the canola seed went up, and we did. But again, we’re within a percentage point of 98.5 per cent control so weed seed size isn’t a big factor in control.

Looking at weed seed number, once you have over 100 seeds going through, we were back up at that 98 per cent control.

As we increased the amount of chaff going in, initially our control increased, which may be that there’s more deflection within that mill. Those seeds get hit an extra time or two, and then it started to taper off. But again, we are in the 98 to 99 per cent control so it’s not going to have a huge impact in the field.

There was a similar story with chaff type. We did have less control in our canola chaff but we were running volunteer canola seeds through the seed destructor so there was likely a background presence of volunteer canola in our canola chaff that we did not account for. But again it’s by one-half per cent and we are still getting 98 to 98.5 per cent control.

In summary, what we found with the seed destructor was if you can get the weed seeds into the seed destructor you’re going to kill most of them – greater than 95 per cent.

The big question now is how does it work in the field? The answer is we don’t know yet. We have an ongoing study with the seed destructor in 20 producer fields where the seed destructor is in the field at harvest time. We harvest with the seed destructor and compare it to a pass with the seed destructor not milling the chaff. We learned a lot of lessons in 2017.

The first is that air velocity is really key. Chaff needs to be moved from the sieves, up and into the input of the tow behind Harrington. In order to get the chaff from the sieves, it has to go up into an input tube, and takes a fair bit of air velocity. If your air velocity is too low, your machine will plug. And if you don’t catch the plug fast enough, you end up with burning belts.

Greener, wet material also doesn’t work. We know it takes a lot more effort for the combine to thresh green or wet material. It’s a similar story with the mills. You need higher air velocity, and without it the green, wet material can plug where it forms a nice solid block of really hot, wet chaff in the blower. Green, wet material doesn’t grind well, either. So if you have green material in the field desiccation or swathing is going to be needed to dry the material down.

The other complication the tow behind HSD is a big machine that has problems with hills. The integrated seed destructor or the Seed Terminator makes a lot more sense for Western Canada. The research that’s been done in Australia shows that the tow behind unit and the integrated unit are very similar in terms of their control, so it’s still a valid test for those integrated units in Western Canada.

An example from a single field in 2017 shows some interesting results, although very preliminary. We compared photos from an untreated and treated Seed Destructor pass. There was substantially less volunteer canola in the treated pass after harvest. There is still some volunteer canola, but there’s substantially less.

We hope to start seeing benefits in the spring of 2018, but it is a three-year study. We’ll be back on the same locations for the next two harvests so that we can take into account the seed bank buffering that we’ll see in terms of our treatments.

These are new strategies. There’s always going to be bugs to work out, but they can be very effective in helping us manage the herbicide resistance that we’re currently facing.

For more stories on this topic, check out Top Crop Manager's Focus On: Herbicide Resistance, the first in our digital edition series.
Published in Weeds
New data and analysis from a survey of barley samples from across Alberta has the potential to help producers get more feed value from barley.
Published in Cereals
The Manitoba government appointed nine members to the newly formed Manitoba Agriculture Research and Innovation Committee (MARIC), Agriculture Minister Ralph Eichler announced on June 11, 2018. 
Published in Corporate News
Many farmers grow corn and soybean in rotation to avoid the continuous corn yield penalty, but now there’s another reason to rotate. Scientists at the University of Illinois have provided further evidence that rotating crops increases yield and lowers greenhouse gas emissions compared to continuous corn or soybean. | READ MORE
Published in Agronomy
Times change and so do cropping practices, but century-old cropping system experiments continue to give back, thanks to the foresight of researchers who established and maintained the plots for more than 100 years. A recent analysis of nitrogen (N) inputs and removals found a surprising result in a long-term study in Lethbridge, Alta. Nitrogen removal in three different wheat rotations could not be solely attributed to N fertilizer or mineralization.
Better winter field survival is a central goal of Prairie winter wheat breeders. However, over the last few decades, making gains in this trait has been very challenging. So a team of researchers is deciphering the genomics of winter survival to further advance the development of varieties that survive and produce good yields no matter what the winter weather is like.
Published in Plant Breeding
Until recently, iron (Fe) deficiencies in field crops in the prairies were mostly unheard of until soybean acreages began to expand. In Saskatchewan, with the growing acreage of soybeans, iron deficiency chlorosis (IDC) began to show up in some soybean fields under certain soil and environmental conditions.
Published in Soybeans
In Western Canada, more phosphorus (P) continues to be removed in cropping systems than is being replaced. On average only about 75 per cent of P is being replaced every year, and although the gap is closing, it is probably not quick enough.
Published in Fertilizer
Rust is one of the issues targeted in a major project to advance disease management in fall rye. Not only is this project breaking new ground by breeding for rust resistance in western Canadian rye cultivars, but the research could also help shed light on some of the basics about this little-studied disease problem on the Prairies.
Published in Diseases
Fusarium head blight (FHB) on canaryseed is on the radar for growers and researchers.  Although it was only recently confirmed at the University of Saskatchewan by Paulina Cholango Martinez and Randy Kutcher, Kevin Hursh, executive director of the Canaryseed Development Commission of Saskatchewan, says that Fusarium has been showing up in seed tested for germination when a disease screening was also conducted.  
Published in Diseases
Although oats are less susceptible than other cereals to Fusarium head blight (FHB), this disease can impact oat yield and quality when conditions strongly favour the disease – as they did on the Prairies in 2016. So, researchers are working to better understand FHB in oat, to develop oat varieties with even stronger FHB resistance, and to help ensure the grain remains safe for humans and livestock.
Published in Diseases
The fungal disease Verticillium longisporum was first detected in Canada in a canola field on a farm in Manitoba in 2014. The results of a subsequent national survey led by the Canadian Food Inspection Agency (CFIA) and released in 2016, detected the presence of the pathogen V. longisporum in varying levels in six provinces in Canada: British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, and Quebec.
Published in Diseases
Lawrence MacAulay, Canada's minister of agriculture and agri-food, announced an investment of $80 million to replace the Centre for Plant Health in Sidney, B.C. The Centre is a Canadian Food Inspection Agency (CFIA) diagnostic testing, research and quarantine facility, with both laboratories and greenhouses. This funding, a Budget 2017 commitment, complements recent federal investments in science and laboratory infrastructure proposed in Budget 2018, according to a press release from the CFIA.
Published in Corporate News
In Canada, the Global Institute for Food Security (GIFS) at the University of Saskatchewan conducts research into transformative innovations in agriculture in both the developed and the developing world.
Published in Plant Breeding
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