Why it matters: Mycotoxin contamination in crops can have a huge economic impact for farmers and biofuel producers, and ingestion by humans or livestock can have serious health consequences, including death.

“I guess you could say the discovery was an accident,” Dr. Mark Sumarah, a mycotoxin and fungal expert at the London Research and Development Centre told Farmtario. 

Sumarah and his colleague Dr. Justin Renaud were originally seeking to learn more about a mycotoxin known as orchotoxin A and the potential risk of it to contaminate Canadian grapes, and consequently wine. Sumarah says orchotoxin A is a significant mycotoxin globally, but there was little data on its effect in Canada. 

Mycotoxins are toxic metabolites produced by fungi that colonize crop species which helps them to survive on plants, but when ingested they can put the health of humans and livestock at risk. 

Several years ago, the researchers were looking at the fungus Aspergillus to search for orchotoxin A, and found that Aspergillus produced not only orchotoxin A, but another type of mycotoxin known as fumonisin. Sumarah says this wasn’t unexpected, but what was a surprise is that the fungus produced strains of fumonisin that no one had seen before.

What was interesting about these compounds, says Sumarah, is that although every previously known fumonisin contains a nitrogen molecule, these new ones did not. 

“This made us very curious,” say Sumarah, and he and Renaud did further work to determine that nitrogen is the single-most important factor in the toxicity of fumonisins. 

Sumarah says “we thought that was the end of the story” but when a new researcher who specializes in enzymes, Dr. Chris Garnham, started working at AAFC in London, the team decided to delve deeper into the mechanism behind the production of the fumonisins that lacked nitrogen. 

“We figured it had to be an enzyme,” he says. 

The team then successfully isolated the enzyme responsible for converting some fumonisins into types that lack nitrogen, and began collaborating with Lallemand Inc. through a Canadian Agricultural Partnership project to commercially develop the enzyme for the detoxification of fumonisins. 

Lallemand is a privately held company based in Quebec that produces yeast, bacteria and specialty ingredients for numerous industries including baked goods, animal feeds, and biofuels, with the latter being the main target of the enzyme for the company. 

Like Deoxynivalenol (DON) or aflatoxin, fumonisins can contaminate crops such as corn and wheat and cause illness or production challenges for livestock, and become concentrated in distillers grains from biofuel production. Sumarah says that fumonisins are a worldwide problem and he has colleagues in areas where corn is a staple in the diet, such as South Africa and Latin America, who are concerned about fumonisins related to human health. Fumonisins have been linked to esophageal cancers and there is suspicion they are linked to neural tube birth defects and other cancers. 

Although DON is the biggest concern in Ontario corn, fumonisins are a significant problem in the southern U.S., and Sumarah says it is detected here. “Fumonisins would fall more in the middle [between DON and aflatoxin], but they are there. It’s something that needs to be monitored for.

“Although fumonisins are currently not a big problem in Canada, they are very likely to be a threat to Canadian crops as the climate warms up.”

The enzyme is now patent pending and shows great promise to be used as a tool to remediate fumonisin-contaminated food and feed, helping not only producers and animals but the biofuel industry, says Garnham. 

Although commercialization of the enzyme is several years away, the research trio are interested in finding an enzyme that will tackle DON.

Kristy Nudds is a reporter for Farmtario. This article was originally published at Farmtario.

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“It was a really major, widespread issue,” says Art Schaafsma, a professor in field crop pest management for the University of Guelph’s Ridgetown Campus. He says the last time the industry saw widespread issues with DON was in 2006 when producers were shocked to find contamination levels up to 10 parts per million (ppm). But in 2018, some producers saw levels of over 50 ppm. “The whole industry was up in arms about what to do with all this corn.”

Except for the DON contamination it was a high-quality crop, and most went to ethanol plants, with some byproducts reaching western Canadian feedlots.

Mycotoxin contamination poses challenges for the industry because the toxin doesn’t break down, but accumulates in byproducts.

Across Canada, DON is still the most economically significant mycotoxin. It can occur across all grain types and is associated with infection by Fusarium graminearum, the pathogen that causes fusarium head blight (FHB) in wheat and gibberella or fusarium ear rot in corn.

Higher-yielding corn hybrids tend to be more susceptible to DON contamination, and conditions that are ideal for corn are also ideal for toxin development, Schaafsma says.

“Years ago we’d have sporadic problems with DON. Every once in a while we’d have a larger outbreak. But yield is king, and the outbreaks are becoming more frequent and they’re hitting harder all the time.”

Oats and barley research

In Western Canada, fusarium is less of an issue, but there’s little room for complacency.

Sheryl Tittlemier, a research scientist at the Canadian Grain Commission’s Grain Research Laboratory, says the CGC annually analyzes samples of wheat, oats and barley for its cargo-monitoring program, as well as samples from the harvest sample program. The latter are used for research in grading factors such as fusarium damage.

Two mycotoxin groups are economically relevant in Canada: fusarium mycotoxins and ergot alkaloids, which can cause issues in feed grain. Both types depend on weather during the growing season, Tittlemier says.

A third mycotoxin, ochratoxin A (OTA), doesn’t occur in the field but can become a problem in stored grain.

The CGC just wrapped up a surveillance study in milling oats in collaboration with the Prairie Oat Growers Association (POGA), comparing mycotoxin concentrations year to year.

“When we looked at the harvest samples there was a wider range of DON concentrations than in the samples we obtained from processing facilities or shipments provided by grain handlers,” Tittlemier says. “We’re not seeing high levels of DON.

“This indicates that the industry is aware of the DON and is managing what ends up in the oats that they’re using. This data is proof that management is having an effect.”

In barley, DON presents more of a problem, says Marta Izydorczyk, a research scientist and program manager for barley at CGC.

“FHB is spreading in Western Canada — initially it was just in Manitoba but we’ve started to see it in the other western provinces,” she says. “For farmers, FHB on malting barley means lower yield and the likelihood that their barley won’t be selected for malting.”

The maximum limit for DON in barley is one ppm, says Izydorczyk; malting barley with levels above this is rejected.

Fusarium has a secondary impact in malting barley: if barley with low levels of DON is selected, fusarium and other fungi can grow and proliferate during malting, producing even more DON.

In collaboration with the Brewing and Malting Barley Research Institute, the CGC is currently testing an innovative post-harvest treatment developed by a Scandinavian company called ThermoSeed. It has the potential to eliminate the pathogen during malting and brewing. The ThermoSeed process can treat up to 1,500 kg of grain per hour, and is already used commercially in Sweden, Izydorczyk says.

“The project’s objective is to determine whether the ThermoSeed process can be applied to malting barley with low pathogens and low DON levels without any negative impact on seed germination and malting quality,” she says.

A sample of last year’s crop was shipped to Sweden and has already been treated and returned, she adds. “The results are looking promising — there are definitely no negative effects on barley germination.”

Sampling protocol

Mycotoxin contamination doesn’t currently affect grade, although it affects price — Schaafsma points to discounts in Ontario corn of up to $60 per tonne for DON contamination last year. The CGC has initiated a consultation on whether DON should become an official grading factor, but Canadian elevators do test for DON if fusarium is an issue or if buyers request it.

Last year, irregular readings from corn samples at elevators left many Ontario farmers disgruntled, Schaafsma says.

In some cases a farmer would deliver a load of corn, which would be sampled and tested and given a high mycotoxin reading, and then wouldn’t be allowed to dump the load, he says. “He’d bring the same load back, it would be retested and it would be fine. There was no confidence in the testing, either for the buyer or for the seller.”

The Grain Farmers of Ontario asked Schaafsma’s team to evaluate sampling protocols to assess whether probe samples were part of the problem. Schaafsma’s team found no issues with probe sampling. Nor did they find problems with the ELISA test kits used to evaluate DON levels, but they did find problems with sub-sampling in the grading house, he says.

There, grain would be tested for grading factors, and then a small random quantity of the grain would be siphoned off and run through a mycotoxin test.

There were issues with the ways samples were being selected and ground for the test, says Schaafsma.

“Within a two-kg sample we could get numbers ranging from five to 15 depending on the quantity of grain you took from the sample. We took a number of tests to see how much variability there was and the variability was high,” he says.

Darrall Marshall, operations manager at G3 Glenlea, says there is no standard practice for mycotoxin tests at elevators in Western Canada. He says elevators follow standard formulas to sample grain. Samples go into the grading room and are tested according to CGC grading standards. Grain is ground for DON tests, but neither the tests nor the grinders are regulated for this — instead, elevators follow protocols set by grinder manufacturers.

“If it’s not done absolutely precisely, you’ll get different numbers because it’s parts per million you’re dealing with. And human error can be a factor,” Marshall says, adding. “Inconsistency in the process will lead to different results.”

Schaafsma presented his findings to an industry meeting in late August, and says some elevators have already made changes to what they’re doing.

“We’re trying to set up a standard practice so we can have more confidence in the sampling. We hope for the new crop to have something in place for corn so people don’t need to be upset,” he says.

“Sampling is so key to understanding what you have, so you can’t be too careful to get the right result,” he says. “It’s way beyond just taking a cup of grain and testing it.”

Schaafsma’s team is currently developing a sampling system farmers can use to test their grain before it leaves the farm. “It’s easy to sample dust with a vacuum while grain is being transferred, so we did some work with wheat and we’re now doing it with corn where we’re looking for a relationship between what’s in the dust and the grain,” he says.

“This would give farmers results right away, so they know if they should unload a given load or blend it off and try again.”

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Importers of corn — organic or otherwise — from India, starting immediately, first must sample the corn, upon arrival in Canada and provide test results to the Canadian Food Inspection Agency.

The sampling must be done immediately after arrival at the Canadian destination, CFIA said in a release Tuesday, because mould can grow and produce aflatoxins during shipping. Sampling and analysis conducted prior to shipping will not be accepted.

Shipments will only be released with an original certificate of analysis from an accredited lab showing the shipment comes in below the 20 parts per billion (ppb) level, CFIA said.

Seen mainly in imports of food and feeds from tropical and sub-tropical regions, aflatoxins are toxic byproducts of mould growth and are considered a potent carcinogen.

Aflatoxin contamination, at sufficient levels in affected livestock, can limit immune function, compromise resistance to infection and reduce animal performance. Consumed at higher levels, doses of aflatoxins can be fatal.

Canada’s Feeds Regulations limit aflatoxin levels in imports of corn or other feed ingredients to 20 ppb and prohibit corn deemed to be musty, mouldy or damaged from heat or any other cause that would render the feed unfit or unsafe for feeding.

CFIA recommended importers, buyers, feed millers and livestock producers ask for further information from their suppliers on the sources of any corn and contaminant specifications on any ingredients they buy.

USDA’s Foreign Agricultural Service (FAS) staff at the end of April projected India’s total 2014-15 corn exports to come in at about 1.5 million tonnes, down from 3.9 million in 2013-14. — AGCanada.com Network

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That’s a far cry from just a few years ago, when the biggest question about fungicide use on cereal crops was whether it was even worth doing, especially during an era of lower grain prices.

But Hebert has the numbers to back up this strategy, having run on-farm trials early in the adoption curve to determine how the economics of fungicide applications on wheat stacked up.

“We always do three years of testing. No numbers or data are as good as the ones you get from your own farm,” Hebert says. “After three years, if the return on investment is always positive, we adopt it whole farm.”

In this case those numbers did add up, and they have continued to show a payback when he has periodically revisited the question over the years. Basically, he says, the numbers have never dipped into the red. So now every wheat crop gets fungicide applications.

“It has always covered at least the cost of the product and the application,” Hebert says.

Lethbridge, Alta.-area farmer Henk Kamper echoes Hebert’s sentiments, saying fungicide applications are an important part of their crop protection strategy, so his family, which farms under the Kamper Enterprises banner, doesn’t waste a lot of time every season wondering if they should fill the sprayer.

While they farm in an area with drier conditions, the Kampers grow under irrigation. This can build disease pressure that might not otherwise exist by creating the perfect conditions for its development.

“For us the question with fungicide applications on our wheat isn’t ‘if,’ but ‘when,’” Kamper says.

Back on the Hebert farm, the fungicide mainly goes down through their ground rig, using double-sided nozzles, a system Hebert says gives the most consistent results. But when the inevitable time crunch hits the 8,000-acre operation, the total coverage target remains most important.

“I’d rather do it with our sprayer, but if time won’t permit that, we have no problem calling in a plane or helicopter,” Hebert says.

Hebert says that while the aerial results aren’t as consistent, any application still has a worthwhile impact on yield and quality. He stresses, however, that aerial application is a last resort and his much preferred option is to go in with a ground rig. He strongly suggests using double-sided nozzles and, if necessary, slowing down a bit to get proper coverage.

“If you’re going to do a pass, get the best coverage you possibly can,” Hebert says.

• More Country Guide: Whether to spray for fusarium: flowering period is key

Kamper says their operation is similar, and they’re likewise dedicated to doing the job right, using a system with three main pillars.

At application time it’s mainly a question of using the right equipment and getting the spray mix right. Kamper says they use between 15 and 20 gallons of water an acre, depending on which fungicide they’re spraying. Less than that will mean incomplete coverage. They also use double-sided nozzles (see below) to ensure coverage on both sides of the heads.

“The right nozzles, the right water volume, the right timing — this is our strategy to get the most out of our fungicide applications,” Kamper says.

Once the application system has been refined, the main challenge is hitting a narrow spray window. And while there’s been some debate over the years about what the best timing is, that’s increasingly become a settled question, according to one industry player.

Every fall, after the harvest at Richardson International’s Kelburn research farm, just south of Winnipeg on the banks of the Red River of the North, Wes Anderson spends a few days pouring over an Excel spreadsheet of the latest data in his ongoing fungicide trials.

Anderson, the company’s agronomy manager, has spent a lot of time over the past few years looking at optimal fungicide timing on wheat crops. He’s currently got about 10 years of solid data from farm trials, as well as anecdotal evidence from the company’s team of agronomists situated throughout Western Canada.

“We did the first of our trials with what are now older products — Tilt and Headline,” Anderson says. “Then we did lots of trials with Folicur, and lately we’ve been using the newest products, like Prosaro. I think we’ve got a lot of good data.”

That data is sending a clear message, Anderson says. Growers looking for the best time to apply fungicides should be targeting the heading stage most years, with earlier applications only in the event of heavy pressure from leaf diseases that could hit the flag leaf and hamper yield.

“Our Kelburn data shows that four years out of five, applications at the T-3 (heading) stage give the best economic results,” Anderson says. Partly that’s because of a mild yield boost, but mainly it’s a question of crop quality, with the heading-stage applications keeping a lid on fusarium-damaged kernels and DON mycotoxins, and therefore preventing downgrading.

A representative of one of the leading fungicide manufacturers agrees this seems to be the consensus that’s emerging.

When Troy Basaraba joined Bayer in 2003, cereal fungicides were still very much in their infancy. Folicur was just emerging and the ongoing debate amongst growers was over whether or not there was a compelling economic case to be made for the applications on wheat.

Now, the question has become what’s the optimal timing for fungicide applications, and Basaraba has been heavily involved in recent years in a Bayer program that runs strip trials throughout Western Canada in commercial fields to compare various fungicide treatments.

“Initially the thinking was you should protect the flag leaf from leaf diseases at all costs,” Basaraba says. “We’ve seen that change over time and evolve to more focus on protection from fusarium head blight. I would say that over the past six years or so, we’ve seen a move from flag-leaf timing to applying it at heading time.”

There are a number of factors that have gone into this evolution, Basaraba says. New products offer multiple modes of action and better protection from fusarium. Other farming practices such as minimum- and zero-till farming systems have changed the environment for the disease, leaving much more crop residue on the field surface where it can act as a host to the disease. Then there’s been the general spread and growth of disease pressure throughout the region, so that even parts of the Prairies such as Alberta where the pressure has been lower are grappling with this new reality.

“They’ve definitely got it there — it’s just less than everywhere else,” Basaraba said.

Basaraba agrees with Anderson, saying timely scouting can help refine the appropriate application timing in season, and that it’s always going to be a balancing act between protecting the flag leaf during times of high pressure from the leaf disease complex, while at the same time grappling with the perennial challenge of fusarium.

• From the Grainews website: Precision matters with fusarium

“Basically it’s Agronomy 101,” Basaraba says. “You need to keep your nose in the crop.”

While Basaraba concedes that every growing season is going to vary, he says the numbers on his spreadsheets don’t lie, and the question of what the best fungicide timing is has become a lot closer to settled in his mind as season after season of data have accumulated.

“I think it’s quite clear that most seasons, you’ll get better yield protection, better response and a better return on investment at heading,” Basaraba says.

Basaraba says typically the portions treated at head timing have about a half a bushel more yield. And even more importantly, they’ve generally got better grain quality.

Back on the farm, both grain growers confirm that they’re mainly shooting for head timing applications these days.

“We apply at head timing with fungicides, and we see that timing as the best,” Kamper says.

It’s not even necessarily a question of yield, although there is likely some yield benefit. For their farm, the key question is quality. That’s what they’re paid for and by spraying just at the time of heading and flowering, they protect quality and prevent damaged kernels and elevated levels of mycotoxins.

Another wrinkle in the operation is that they include both wheat and grain corn in their rotation, providing a second potential host crop for fusarium head blight. But even without the corn issue, the farm and others in the area have to face the simple fact that — like most other parts of the Prairies — fusarium has become a fact of life and the disease is always there, just waiting for the right conditions to flourish in the crop canopy, making hitting it with a fungicide at heading a perennial goal of the farm.

Hitting that head-timing window, however, is easier said than done, because it’s such a narrow one. Just four or five days long, for the typical modern commercial-scale grain grower it makes for a lot of ground to cover, Kamper concedes.

“You can do it if you’re set up for it,” Kamper says. “Keep scouting, and be ready to move as soon as they head out. Be ready for it and go at it as hard as you can.”

Producers can also do a few things earlier in the season to make life a bit easier, such as taking care at seeding time to do a good job to get even germination and emergence so the entire field begins heading at the same time, setting up conditions for a more successful application.

Hebert agrees head timing seems to deliver the best results, although he admits he’d hit it at flag-leaf stage too — if there were only enough days to do the work. As it is, they typically blend a low rate of fungicides and spray them along with weed control products, hoping to keep the leaf diseases in check until the head-timing applications.

“This means we’re typically applying our weed control products a bit toward the later end of the application range,” Hebert says.

It’s all just part of the farm’s central philosophy, which assumes every crop that goes into the ground has a 100 per cent chance of remaining healthy and hitting its full yield potential.

“We do everything we can to manage the evironment and fertility to protect that 100 per cent potential,” Hebert says.

“It really is a bit of a balancing act,” Anderson agrees. “It all comes down to how bad the leaf disease pressure is earlier in the season, and if it gets really bad, you can’t always wait for heading.”

In recent years, fusarium head blight has become endemic in Western Canada. Unlike leaf diseases, which frequently have to be blown in from farther south, this disease winters here. It’s always laying in wait, ready for the next time weather conditions line up for a full-blown epidemic. That makes it the more important of the diseases to manage proactively, and the more likely candidate to deliver a bigger bang for the buck and effort.

One thing that has become apparent in recent years is that farmers are taking cereals management much more seriously than they used to. They’re optimizing their fertility and weed control packages, and they have increased their use of fungicides and are paying more attention to application timing as part of that trend.

“We’ve come a long way with wheat,” Anderson says. “These crops are much more intensively managed than they used to be just five or 10 years ago.”

Another area where there have been improvements is in the available fungicides, such as Prosaro, one of the latest offerings. Initially Anderson says he wasn’t expecting much beyond a little modest evolution in efficacy, but instead he’s finding it’s delivering a bit more than expected.

“We’re finding it (Prosaro) is delivering longer and better protection,” Anderson says.

Bayer’s Troy Basaraba agrees the exception to that rule is when there’s “massive” leaf disease pressure, something like rust spores blowing in from down south during a spring with good conditions for the disease’s development.

Under those conditions, Basaraba agrees with Anderson that earlier applications can have a positive return on investment too.

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