Could fungicide resistance develop on your farm? The answer to that question really depends on how you deploy fungicides in your fields, says Agriculture and Agri-Food Canada research scientist Kelly Turkington.
On this episode of RealAgriculture’s Resistance Management School, Turkington explains that fungicide resistance really is a numbers game. He notes that a barley or wheat field can contain billions and trillions of plant stems that can harbour plant pathogens. Most of those pathogens will be susceptible to the fungicide a grower applies to the field, but there may be a small percentage that has a genetic make-up that either makes them less sensitive or even resistant to a fungicide product.
What drives an increase in the less sensitive or resistant pathogens is the frequency of fungicide use, says Turkington. He notes that multiple applications within a season, and operating in tight rotations, can lead to overuse of a particular fungicide, increase selection pressure and fuel growth of the resistant pathogen within the field.
Turkington says the first sign a grower might have a resistance problem is when they see declining fungicide product performance. In extreme cases, the pathogen can become completely insensitive to the fungicide you are applying.
But there are steps growers can take to safeguard fungicide performance and ensure resistant pathogens do not gain a foothold in their fields.
For Turkington, the number one rule is to use fungicides only when they are necessary. During a growing season, he advises growers to use a fungicide only once, if possible. “If a fungicide is required more often, look at rotating fungicides active ingredients, and consider products that contain a mixture of different active ingredients,” he adds. “That will greatly decrease the risk that you are going to select for fungicide resistant strains of the pathogen within your field.”
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