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Wireworm specialist provides update on latest IPM programs


November 30, 1999
By Myron Love

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Agriculture and Agri-Food Canada entomologist Dr. Bob Vernon, one of Canada’s leading authorities on the control and elimination of wireworms, recently updated Saskatchewan potato growers on the latest developments in the fight against wireworms.

Agriculture and Agri-Food Canada entomologist Dr. Bob Vernon, one of Canada’s leading authorities on the control and elimination of wireworms, recently updated Saskatchewan potato growers on the latest developments in the fight against wireworms.

Wireworms are click beetle larvae that usually spend three or four years in the soil, feeding on decaying vegetation and the roots of plants such as potatoes, corn and wheat. In the spring, during planting, wireworms mostly congregate just below the soil surface feeding on grasses, weeds and winter cover crops, Vernon said.

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“Although you might use an insecticide while planting, you won’t kill many wireworms,” he said. “But control must be close to 80 per cent in the first month after planting.”

Wireworms are attracted to carbon dioxide, Vernon noted. The primary source of carbon dioxide during spring planting is seed pieces. A granular or liquid wireworm insecticide planted in the seed furrows provides growers a good chance of killing most wireworms in a well-fallowed field, he said.

Vernon identified a number of insecticide options that have been used in the past to control the insect pests. He noted that Thimet, Temik, Dyfonate, Furadan, Counter and Lindane are no longer being licensed for use in Canada – although most are still available for use in the United States – while Mocap has never been registered in Canada and chlorpyrifos is being used by growers in British Columbia.

Some potential newer insecticides he listed are imidacloprid (Admire), clothianidin (Poncho), thiamithoxam (Cruiser), fipronil (Regent), tefruthlin (Force) and chlorpyrifos (Pyrinex).

But do these new products work and how well do they work?

To answer those questions, Vernon displayed slides showing the results of field trials across Canada. Over a six-year period (2000 to 2005) fipronil used as a spray proved to be the most effective alternative in killing wireworms, he said, while in field trials in B.C., Pyrinex alone, or in combination with Poncho or Cruiser, worked best.

In Canada, Pyrifos 15G (for damage and wireworm suppression only) and Pyrinex have been registered for use, he adds, although the products are not registered for use in the U.S. In light of this, Vernon cautioned that Canadian growers shipping potatoes raw or in processed form south shouldn’t use these products.  

Clothianidin and Poncho 600 have also been approved for use in Canada, he said, although Poncho 600 is only approved for seed piece treatment damage suppression.