LEWVAN, Sask. – Spraying an entire crop for pests might be overkill, an entomologist told farmers at a field day July 27.
Mike Dolinski, an entomologist with Agri-Trend Agrology, said farmers should make better decisions about spraying, not only for economical reasons but also to meet public expectations.
Dolinski said consumers are more interested in where their food comes from and how it is grown, with the organic movement showing no signs of slowing down.
But farmers tend to panic at the first sign of insects, he told about 50 people at Farr-Mor Fertilizer’s Field of Dreams project. If one neighbour is spraying, the others think they should too, which could lead to overspraying.
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In doing so, farmers will likely kill parasites and predators that would have naturally helped against some pests. Three parasites control bertha armyworms, he said, but too much spraying can affect their ability to help.
Sawflies are a huge problem this year, with 95 percent of the wheat crop infested at a research farm near Indian Head, Sask.
Dolinski said spraying for grasshoppers may have affected the parasite that controls sawflies.He suggested that farmers deal with bugs differently.
For example, wireworms can take five to 10 years to go from the larva to adult stage. Instead of spraying every year, Dolinski recommended treating for two years in a row, waiting four years, then spraying again.
Flea beetles are usually found at the edge of canola crops. A walk farther into the field may turn up none.
“Why don’t we spray the edge, not the whole field?”
Another strategy is to increase seeding rates for the first two rounds. Feeding the beetles at the edge may be enough to keep them out of the rest of the crop.
Mowing ditches will keep flea beetles and sawflies from wintering in the tall grass at field edges, he added.
Dolinski said fall is the time to develop an action plan against insects for next spring.
“If you see lots this fall, you’ll have lots next spring,” he said.
Although grasshoppers appear to be under control this year because of cool, wet weather, he said they could lay a lot of eggs if the fall is long and hot.
Agri-Trend has been approached by the Canola Council of Canada and the World Wildlife Fund to work on an integrated pest management initiative. The work could result in a strategy to help farmers make better spraying decisions.
