Fusarium head blight is a notorious fungal disease threatening small cereal grains like wheat. Its effects are far-reaching and result in millions of dollars in economic losses every year, making it one of the most significant crop diseases faced by Canadian wheat growers.
Not only does this disease reduce crop yields and seed quality, but the fungus responsible for the infection produces dangerous mycotoxins including one called DON (deoxynivalenol). Even small amounts of this toxin can cause major health issues for humans and animals, which is why it has become heavily regulated across grain markets.
“If a load of grain is contaminated with a mycotoxin like DON, it could be rejected,” says Dr. Lipu Wang, Research Officer with the University of Saskatchewan’s Crop Development Centre (CDC). According to Wang, “This is a big economic challenge for western Canadian wheat growers.”
Developing fusarium resistant varieties with low levels of DON is a top priority for wheat breeding programs. Unfortunately, their efforts have been stunted due to a lack of available options to test for the mycotoxin.
According to Wang, “The industry agrees DON is an issue that should be addressed in our breeding programs, but there aren’t many labs in Western Canada that can measure mycotoxins.”
To overcome this, Wang joined forces with Dr. Randy Kutcher (University of Saskatchewan Chair of Cereal and Flax Crop Pathology). With funding support from the Saskatchewan Wheat Development Commission and the Saskatchewan Ministry of Agriculture through the Agriculture Development Fund, their research team was able to develop a rapid, cost-effective method for detecting DON in wheat.
Wang and Kutcher approached the challenge by modifying an existing testing method known as Liquid Chromatography Mass Spectrometry (LC-MS). As Wang puts it, “We customized the method specifically for the needs of wheat breeders.”
“The time needed to test a sample for DON was a big limitation for breeding programs,” said Wang. “With this new method, we reduced the testing time from 20 minutes to two minutes for each sample.”
By reducing the testing time, Wang’s team can process hundreds of samples at a time. “Right now, we can screen around 200 samples each day with this method,” said Wang. This is exactly the kind of testing capacity a breeding program would need.
While the team found ways to cut back on time and costs, they made sure not to compromise on accuracy.
“We used a very strict validation method for every step of our method,” said Wang. “It is the same validation method recommended for medical assays by the United States Department of Agriculture.”
This new approach for detecting DON in cereal grains is already helping wheat breeders in Western Canada. By implementing this testing into their programs, breeders can speed up their screening process and improve their selection criteria for developing fusarium resistant varieties with low DON.
After the success of their DON testing method, Wang and Kutcher took their work one step further.
“Fusarium doesn’t only produce DON, it can produce other mycotoxins, as well,” said Wang. “So, we developed a method that can detect up to seven different mycotoxins in wheat.”
This secondary method was designed as a proactive approach to disease management. “With it, we can know which mycotoxin is dominant in western Canadian wheat and watch for changes and trends,” said Wang.
The method is already being used by researchers at the CDC and will help the industry respond more quickly to changing and emerging disease threats.
Wang hopes to continue to serve the Saskatchewan wheat industry through his research and encourages anyone interested in these newly developed methods to reach out to the CDC, saying, “If there are breeders and companies interested in applying these methods, we are very happy to help.”
“We were interested in learning how these different residue management strategies would affect the condition of the soil and the crop yields in the following growing seasons,” said Schoenau.
The three-year project began in the fall of 2015 near Central Butte, Saskatchewan. Each test plot spanned nearly five acres and contained residue from a recently harvested flax crop. The research team managed the residues on each plot using either vertical tillage, tandem discing, raking and burning, or no-till practices. Come spring, each plot was seeded to red spring wheat, while the subsequent two years were seeded to peas and then to canola.
The research team evaluated each of the long-term effects of their flax residue management strategies based on soil health and structure, crop yields, and cost of production.
“The first thing we measured was the effect of flax residue management practices on soil water infiltration over three crop years,” said Si, adding that, “In Saskatchewan, water is a major limiting factor for crop production.”
Flax stubble burning didn’t appear to have a major impact, but tilling reduced the soil’s moisture content compared to untilled plots.
“That is what we expected,” said Schoenau. “Tillage tends to dry out the soil, because if you get rid of that stubble on the surface you don’t have as much snow trap during winter.”
During the first year of the study, they found that vertical tillage reduced air permeability of the soils compared to the other treatments. According to Schoenau, “We looked at this because the roots need oxygen and so do the microorganisms. We need aeration to allow the microorganisms to do their job like fix nitrogen.”
The researchers believe these findings might be explained by their use of rolling baskets behind the vertical tillage equipment which may have increased the number of fine pores in the surface soils.
Aggregate size and stability was another important consideration as predictors for soil erosion.
“We found that aggregate size wasn’t affected much,” said Schoenau, “but the tillage and burning practices did tend to decrease aggregate stability.”
Fortunately, the negative impacts of their tillage treatments appear to be short lived. According to Si, “The negative effects of tillage seem to disappear after a couple of years, so it doesn’t hurt as long as you don’t do it every year.”
The same couldn’t be said for burning, especially when considering soil fertility.
“Burning did show a small increase in phosphorus availability the following crop year, but you also lose carbon and nitrogen from the soil which can hurt in the long-run,” said Schoenau. “You may get a bit of short-term gain, but you potentially get some long-term pain from continued burning.”
When it came to crop yields. Schoenau and Si didn’t see any changes in crop yields the following three years after their residue management treatments.
So, what does all this mean for a producer’s bottom-line?
“If there is truly no difference in yield, but there are additional operation costs, it actually doesn’t pay,” said Schoenau.
Schoenau goes on to say, “If you’re able to harvest the flax early on when it’s warm and the straw chops well, you might not need to burn or till. Seeding directly in well-chopped flax stubble worked well, in our study.”
But when harvest conditions are not ideal, Schoenau and Si agree that periodic use of tillage practices are a viable solution to handling difficult crop residues.
“Vertical tillage doesn’t hurt the soil if you don’t do it every year,” said Si. “If the purpose is for residue management and weed control in problem spots then you can do it and the effects will dissipate over time.”
Ultimately, a successful residue management program all comes down to optimizing harvest conditions and paying attention to the needs of the land.
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