Diamondback moths blow in at some point early in the season (thanks, America!), and set about living on the Prairies and in the canola crop for the rest of the growing season.
Jordan Bannerman, entomologist with the University of Manitoba, says that understanding when the moths arrive, through the use of pheromone traps, and how long to scout for this pest will help determine if populations reach economic threshold.
Early July is a great time to be scouting for the plant-eating caterpillars, but don’t quit after one scout, as Bannerman says the pest can go through about four generations in a season.
Bannerman says that there are effective predators in the canola canopy that can keep the population in check over the season.
“The [insect] numbers don’t necessarily climb with each generation — the second or third can be the most numerous,” he says. Heavy rain events and parasitic wasps kill the caterpillars and can be really effective in lowering populations.
If economic levels of the pests are found, farmers are encouraged to avoid spraying during flowering if possible, to protect as many pollinators and beneficial insects. Plus, choose the most pest-specific product possible and, if conditions allow, spray late in the day.
Looking for more about this pest? Watch more Canola Schools here!