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Identifying a common enemy to canola and other crops

October 30, 2023  By Agriculture and Agri-Food Canada

When there is a powerful stain of diseases spreading that can affect the health of crops, producers want to know as soon as possible in order to protect them.

A group of plant diseases, caused by bacteria known as “phytoplasmas” can create yield losses in several types of crops – from highbush blueberries to canola. This affects producers’ bottom lines and the security of our food supply. But the good news: Agriculture and Agri-Food Canada (AAFC) researchers are developing a molecular method to quickly determine the presence of these pathogens early on.

Aster yellows in canola


One project being led by Dr. Tyler Wist, AAFC field crop entomologist, and partners in Saskatoon looks at detecting aster yellows (a form of phytoplasma disease) in aster leafhoppers (an otherwise harmless insect) and tracing the migratory origins of the infected bugs that can transfer the disease to plants.

“We know aster leafhoppers are blown through air currents from the southern U.S. each spring,” says Wist. “So, if we can identify the percentage of leafhoppers carrying the aster yellows pathogen/disease in this migratory population as soon as it arrives in our region – in the spring by surveying the first plants that grow in ditches – then we can give farmers a heads-up on the potential for aster yellows that year so they can plan accordingly.”

Through this project, researchers have developed a new technique that reduces pathogen identification time from one to two days to less than one hour, which is a huge step towards quickly understanding the infection levels in those early-season leafhoppers.

Why is it important to detect the microscopic disease in insects, and not just in the plants? These insects can transfer aster yellows to new plants, which will in turn infect other aster leafhoppers that will then continue the spread.

And why do these phytoplasma bacteria need to be identified early on? Because leafhoppers reproduce quickly. Early detection is key, because controlling the population quickly will help lower the disease transmission in the early stages of the crop’s development when they’re most vulnerable to the disease.

“Phytoplasma bacteria cannot be grown in the lab, so we have to identify them using their DNA signatures, which normally requires lab-based equipment and procedures,” says Dr. Tim Dumonceaux, AAFC research scientist, molecular microbiology. “It takes time for us to get samples back to the lab, by which point the insects could have already reproduced and spread the bacteria to their offspring and more of the crop. With this new test we’ve developed and validated, producers can test for the phytoplasma DNA in a plant or insect onsite in minutes and take action sooner.”

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