Wireworms are on the rise in Western Canada, years after a ban was imposed on the only insecticide effective against them.
“The population appears to have been increasing annually. Every year I get more and more reports of wireworm problems happening,” said Bob Vernon, an Agriculture Canada research scientist from British Columbia.
Vernon’s colleagues across Western Canada have told him that the worms are steadily becoming more of a concern, particularly in cereal crops.
While the worms prefer grasses and cereals, they have also been known to eat pulses and other crops, said Dan Bardi, seed treatment market development specialist with Bayer Crop Science.
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Bardi said the voracious pests can do extensive damage if left unchecked. They are attracted to the carbon dioxide emitted by germinating seeds, and under the right environmental conditions can cause 60 percent losses.
Vernon said lindane was an effective control, with applications every three to four years, because it not only killed wireworms but also the less developed neonate wireworms.
However, the chemical was banned in Canada in 2004 because it was found to remain in the environment for too long.
Bayer and Syngenta have seed treatments for wireworms on the market, but neither product kills the worms. Rather, they use nicotine-based compounds to put the worms to sleep for one to two months. This gives crops time to establish, growing to the point where they can sustain the damage caused by the worms as they feed.
Bardi said finding a compound that will kill the worms without damaging the environment is difficult. Current methods seem to be working to manage the problem, but he has heard producers in hard-hit regions express worry about what will happen in five to six years if wireworm pressure keeps mounting.
Vernon said there is hope for a solution: his research into using fipronil has yielded promising results. It is a chemical approved for wireworms in the United States but has not yet been registered in Canada.
He said small amounts of the chemical, mixed with currently available seed treatments, have shown even better levels of control than lindane.
However, he cautioned that while fipronil is proving effective, it would be several years before it could be available in Canada because a company would have to go through the regulatory process to get it approved.
