Army cutworm damage will force the reseeding of several crops in southern Alberta this spring.
Farmers are advised to scout their fields for the pest.
Alberta Agriculture insect management specialist Scott Meers said May 9 that the problem is centred around Coaldale, with problems also reported in the Taber and Lethbridge regions.
“There’s been some spraying and there’s been some damage, severe enough damage that some of the fields will be reseeded,” said Meers.
“It’s a different species this year. Last year in southern Alberta, it was mostly redback. This year it looks like army cutworm. The beauty of entomology is it’s never the same year to year.”
Read Also
Ag ministers hear request for regulatory change, more infrastructure development
Canada’s agriculture ministers met today in Winnipeg after postponing their usual July in-person meeting due to wildfires.
Winter wheat, winter triticale and alfalfa that was seeded late last summer or fall appear to be the most vulnerable.
Meers said the common denominator is fields that had lots of green growth in the fall. He’s seen 10 quarter sections that have cutworms at threshold levels for spraying, “but that’s usually the tip of the iceberg.”
Cutworm activity is characterized by patches of the crop that aren’t greening up as well as they should. Finding the pests before that stage requires closer investigation for missing plants or bits of dried plant matter lying on the surface.
Jack Feenstra of Chinook Crop Care Ltd. said he has inspected 30 to 40 fields between Coaldale and Carmangay and only two were severe enough to warrant spraying.
“Its extremely variable. Farmers need to check their fields and not just go out and spray it just because the neighbour had them,” said Feenstra.
“There will be patches in the field that are failing to green up in your alfalfa or winter wheat. If your field just stays a miserable pale yellow, the cutworms are grazing off all the green foliage, and you keep on seeing the ugly old stubble from last year.”
He said there has also been winterkill in alfalfa this year, so farmers should investigate before making insecticide decisions.
Meers said cutworms will be munching on crops for two to three more weeks before they pupate and become moths.
“The bigger they get, the hungrier they get because they are fattening up for their next life stage. Their feeding gets more intense.”
There is only one generation of cutworms per year. Natural enemies include species of parasitic wasps.
Economic thresholds for spraying depend on the crop. Five cutworms per sq. metre can destroy a mustard field but cereals and alfalfa can withstand levels up to 50 per sq. metre.
Meers said effective insecticides are available should infestation warrant. The Alberta Crop Protection Guide lists the options.
