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Pest watch: Wind trajectories report released

April 10, 2019  By Top Crop Manager

The Prairie Pest Monitoring Network released a wind trajectories report for the week of April 8, or Week 1 of the 2019 growing season, that provides insight into the possible pest pressures expected on the Prairies.

Wind trajectory models are used as an “early-warning system” for pests. Pests, such as the diamondback moth, that overwinter in the southern United States and Mexico can make their way to Canada through air currents.

According to the Prairie Pest Monitoring Network, if diamondback adults are present in air currents that originate from these southern locations, the moths may be deposited on the Prairies at sites along the trajectory, depending on the local weather conditions at the time that the trajectories pass over the area (e.g. rain showers, etc.). Therefore when analyzing air currents, those currents originating from northwestern and southern U.S. and Mexico are of particular concern because of their diamondback moth significance.


A report compiled by Ross Weiss and Meghan Vankosky from Agriculture and Agri-Food Canada (AAFC) and Serge Trudel from Environment and Climate Change (ECCC) looks at what trajectories have crossed over prairie locations this week.

For the period of April 2 to 8, 2019, there have been 69 reverse trajectories originating over the Pacific Northwest that have crossed over prairie locations. Reverse trajectories are air currents tracked five days back from their arrival date to find their origin. Since March 23, Lethbridge, Atla. has reported the highest number of Pacific Northwest winds, followed by Olds, Atla., Beiseker, Atla. and Dauphin, Man.

On April 7, the first southwestern U.S. and Mexico reverse trajectories, originating over Texas and California, crossed the Prairies. The trajectories hit areas such as Brandon, Man., Regina, Russel, Man., Tisdale, Sask. and Yorkton, Sask.

Winds from Santa Maria, CA are predicted to cross the Prairies over the next five days, passing over Saskatchewan and Manitoba. These ‘forward trajectories’ are based on models that¬†predict the pathway of their trajectory (versus backtracks) and according to the report, these winds are only of interest if they actually end up passing over the Prairie provinces.

In addition to wind trajectories, Manitoba and Saskatchewan run pheromone-based monitoring sites and post numbers to ministry websites to help assess diamondback moth risk. Alberta Agriculture maintains an early warning system of traps in May and June which offer a sense of population migration from southern U.S.

Despite diamondback moth not overwintering well in Canada, winds can still push the pest onto the prairie radar. The pest is a concern for canola producers, and with growing insecticide resistance, diamondback moth is one to watch for in 2019.

Agriculture and Agri-Food Canada and Environment and Climate Change Canada have been working together to study the potential trajectories for monitoring insect movements since the late 1990s. The full wind trajectories report, with maps, is available on the Prairie Pest Monitoring Network blog.


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