Since the first major outbreak in Manitoba in 1993, fusarium head blight (FHB) has established itself in Manitoba and eastern Saskatchewan and continues to move into western Saskatchewan, Alberta, and northern B.C.
Farmers in some parts of the Prairies are now accustomed to dealing with the fungal disease and its dominant strain, F. graminearum, and are incorporating management practices to prevent its spread.
According to Daryl Beswitherick, program manager for quality assurance and standards with the Canadian Grain Commission, a third of all the samples of CWRS submitted to the CGC’s Harvest Sample Program in 2014 have been downgraded due to fusarium damage. The high infection rates were likely spurred on by the soggy weather in Manitoba and Saskatchewan. Only six per cent of those samples downgraded came from Alberta and northern B.C.
Fusarium graminearum affects the development of the kernel, so grain yield and quality can drop significantly. It also produces a toxin called deoxynivalenol (DON), which makes grain unsuitable for milling, malting, brewing and producing ethanol, and limits its use as livestock feed.
Farmers will likely experience grade loss, restricted marketing opportunities, added costs, and lost income as a result of a fusarium infection. According to Alberta Agriculture and Rural Development, losses in Canada have ranged from $50 million to $300 million annually over the past two decades; future losses are projected to run between $30 to $132 per acre depending on the crop and the area.
While weather plays a huge role in the levels of fusarium found in Prairie crops in any given year, farmers can still work to minimize the possibility of infection. They can plant quality fusarium-free seed, select varieties that are less susceptible to fusarium, treat seed, rotate crops, manage stubble and apply a foliar fungicide at the flowering stage.
If all of these steps fail, and fusarium-damaged kernels (FDK) in wheat or fusarium mould in barley are visually detected in the field pre-harvest, producers can adjust combine settings to blow the lighter, damaged seeds out the back. The residue must be chopped and spread, and that field taken out of cereal production for two to three years to lower reinfection rates.
If, despite their best efforts, producers bring in a crop with a high level of fusarium, they should store it separately at 14 per cent moisture in order to minimize the spread of the mould.
But what happens next? With bins full of fusarium-infected grain on their hands, what can farmers do to successfully get their crops to market? If their crop is downgraded due to fusarium damage, is there a way to get it back up?
Acceptable fusarium levels according to grade and crop can be found on the primary grade determinants tables on the Canadian Grain Commission website.
Unfortunately, post-harvest treatment opti-ons are nonexistent at this time. Currently, no effective physical or chemical treatment has been found to neutralize the fungal infection and reduce the DON levels in harvested grain. The levels are affected little or not at all by the application of heat, acids, mycotoxin binders, or the anti-caking agent HSAS (hydrated sodium aluminum silicate).
Cleaning can help
Cleaning contaminated grain in order to reduce DON levels and increase marketability is possible — though the Fusarium Management Plan in place in Alberta and Northern B.C. prevents seed cleaning plants in those areas from receiving and cleaning grain that tests positive for Fusarium graminearum. Infected grain can be cleaned at plants in Saskatchewan and Manitoba.
Because the affected kernels tend to be shrunken and lighter than their healthy counterparts, they may come off the air and screen machine, as well as a gravity table — depending on the size of the kernels impacted. Damaged grains are sometimes also discoloured which means a colour sorter might be effective.
Beswitherick says price differences will determine whether farmers decide to sell fusarium-infected grain as is or take on the cost of upgrading it. For instance if there is little price difference between a No. 1 and No. 2, then the grain will likely be sold as No. 2. When it comes to No. 3, the decision to upgrade may depend on other factors such as mildew. Fusarium damage might not be the only reason the grain was downgraded and, in the end, selling at a lower grade may not only be the more cost-effective option, it may be the only option.
Farmer who choose to clean fusarium-infected grain will end up with a considerable volume of screenings with a high concentration of DON that will not be suitable for livestock feed. These screenings will likely have to be composted, burned, or buried.
Using fusarium-infected grain
- Using it for seed: In areas where fusarium is not established, the primary method of preventing infection is to plant seed that has been tested and is free of fusarium.
Where fusarium is established, fusarium-infected grain can be used for seed according to Manitoba Agriculture, but it will require heavy cleaning. In some areas and situations, farmers may have a hard time finding completely fusarium-free grain for seed.
Research shows that fusarium-infected seed often has reduced levels of germination and vigour. Seed treatments can improve germination of fusarium-infected seed, but they do not prevent the possibility of fusarium infection at the time of flowering.
- Using it for food: The mycotoxins produced by Fusarium graminearum are, first of all, not destroyed through the process of milling, baking, malting, or brewing. They change the colour of flour and its ability to rise; they also impact the taste of beer and cause it to gush out of the bottle. Most malting companies have zero tolerance for DON in barley.
- Using it for feed: DON is not deadly for livestock but it causes reduced feed consumption. Agriculture and Agri-Food Canada sets the maximum DON levels permissible in feed at one ppm for swine, dairy cattle, and horses; at five ppm for beef cattle, sheep and poultry. These levels refer to the livestock’s complete ration so a higher DON level could be tolerated in a blended ration.
Blending is one way to go
Farmers may choose to blend their FHB-infected grain with uncontaminated grain to reach suitable DON levels for feeding to livestock. On its website, 20/20 Seed Labs provides a useful formula for the proportions required to achieve safe levels of DON.
- Divide the acceptable DON level by the actual level in your sample, then multiply this number by 100 to get the percentage of infected grain it is safe to feed.
- Add enough sound feed to your infected feed to bring the percentage up to 100.
For example: your grain has 10 ppm vomitoxin, and the acceptable level is five ppm. Step 1: Divide five (your level) by 10 (the accepted level), to get 50 per cent infected grain. Step 2: you’ll need to add 50 per cent good feed to get feed that is acceptable.
You can find this information online at 2020seedlabs.ca, along with a useful page titled “Fusarium Tests and How to Use Them.”
Farmers may blend their grain on-farm. Some elevators, especially in areas where there isn’t a high level of FHB may purchase contaminated grain to blend onsite.
When all else fails
If all else fails, infected grain can be composted at 60 to 70 degrees C for two weeks to kill Fusarium graminearum. Contaminated grain can also be buried or burned. It should never be dumped directly on the ground. Caution must be taken when hauling, loading or unloading fusarium-infected grain to ensure none of it blows onto roadways, ditches or adjacent land.
Producers have limited choices when it comes to moving fusarium-infected crops off the farm. While cleaning and blending can be beneficial after the harvest, taking action pre-harvest to limit the risk of fusarium damage is still the best medicine. As for dry weather during that crucial flowering period? Farmers just have to keep their fingers crossed.