Fatal attraction: companion planting technique controls wireworms in potatoes
Agriculture and Agri-Food Canada
With spring comes planting season, and with planting season come unwanted guests for more and more Canadian farmers: wireworms. Decades ago these troublesome pests were successfully controlled with chlorinated hydrocarbon insecticides, but these agents were banned in the 1970s and 1980s because they were toxic to animals such as peregrine falcons and bald eagles. They also had a tendency to build up in the soil and, ultimately, in the food chain.
A sustainable and cost-effective solution is within reach thanks to Dr. Bob Vernon, a Research Scientist at the Agassiz Research and Development Centre, and his team. They have developed a new "attract and kill" method using tiny amounts of insecticide to decimate wireworm populations and limit damage to potatoes in the field. The technique can be implemented at low cost with minor modifications to planting equipment.
"With my method, you only need 5 grams of active ingredient per hectare. This new approach is superior not only in terms of reducing risks to the environment and to people, it also kills far more wireworms."- Dr. Bob Vernon, Research Scientist, Agriculture and Agri-Food Canada
Wheat seeds treated with an insecticide act as bait and are planted along with the potatoes. The wheat germinates first in the soil, after about 48 hours. During germination, the wheat produces carbon dioxide, which attracts the majority of the wireworms in the field to the planted potato rows. When they reach the wheat seed to feed, the hungry pests contact the insecticide and die. This takes care of approximately 80-90% of the wireworm population in a field within about 2 weeks after planting, and also protects the potatoes produced later in the summer.
The wheat is planted about 15 centimetres below the surface, which means there is little risk of contact with the vast majority of animal life in a field - except, of course, wireworms. Because so little insecticide is used, residue doesn't build up in the soil.
A number of new low risk insecticides and insecticide combinations are under development using this new "attract and kill" delivery method, and should be available to growers in the not-too-distant future. Other research efforts are also ongoing at Agriculture and Agri-Food Canada to identify alternative methods to control wireworm populations.
- The technique works on all wireworm species, and the amount of wheat co-planted with potatoes does not interfere with the growth or yield of the potato crop.
- Wireworms are agricultural pests that live in the soil and cause severe damage to crops. They are the larvae of click beetles and there are about 30 pest species in Canada.
- Wireworms feed on seeds and plant roots for up to five years, feasting on many crops such as potatoes, corn, cereal crops and many vegetables (carrots, rutabagas, onions, etc.).
- The PEI Potato Board estimated wireworm damage to that province's potato crop alone at $6 million in 2014.
Contribution to the research by the Pest Management Centre.
- Companion planting attract-and-kill method for wireworm management in potatoes
- Agassiz Research and Development Centre
- National pesticide risk reduction strategy for wireworm in potato
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