Well, it turns out alfalfa weevils can’t read road signs.
“We thought it was a southern Alberta problem that doesn’t go beyond Highway 1 — most weevils don’t like it beyond Highway 1 — but lo and behold, we found it all the way through Stettler and Provost,” said Shelley Barkley, insect research technologist with Alberta Agriculture and Rural Development.
“There was a large enough number there that they have been there awhile.”
Barkley and colleague Scott Meers visited 150 alfalfa fields across the province last summer as part of an insect survey of forage crops. While they found plenty of other bugs from one end of the province to the other, the spread of the alfalfa weevil was a surprise — and not a good one.
“This is a nasty little creature, because their larvae are out early in your alfalfa-growing season. In Brooks, they’re there before the first cut,” said Barkley. “Their larva will actually feed on the leaves on your alfalfa, and when they’re really bad, they can shred the leaves, so there’s a yield loss there for sure.”
Another critter that seems to be spreading is the alfalfa blotch leafminer, a small black fly that lays its eggs on alfalfa leaves.
“This was a problem that showed up around Brooks probably in 2004, and it caused quite a bit of yield loss early in the season,” said Barkley.
“Again, we thought this was just a Brooks problem. We didn’t think it was further afield than that, but we found it from one end of the province to the other. We even found it in the Peace. And in some places, they’re really bad.”
Three different species of leafminer flies have shown up in Barkley’s samples, which could affect control measures depending on which species is causing the problems.
It’s too soon for an accurate dollars-and-cents estimate of damage as this is the first year of a three-year project. The goal for right now is to “know how far they’ve stretched.”
“We want to know economic levels so we can make control recommendations for you, but we had no idea that alfalfa weevil was as far north as Stettler,” said Barkley.
“We need to get a baseline, and then we can get recommendations from that baseline.”