If you think flea beetles are worse this year, you’re not alone.
“I haven’t done formal surveying, but I feel pretty confident in saying yes, it is absolutely worse this year,” Angela Brackenreed, the Canola Council of Canada’s eastern Manitoba agronomy specialist, said June 7. “From my personal experience, not that I am long in the tooth, but this is the worst I’ve ever seen.”
The Manitoba Agricultural Services Corporation (MASC) says flea beetle damage has prompted a number of reseeding claims.
“Definitely we’ve seen the bulk of our reseed and spring inspection claims have been canola as of late and the flea beetles being the primary cause of loss,” MASC claims manager David Koroscil said in a phone interview.
Most canola seed is treated with an insecticide, but the clock starts ticking on protection as soon as the seed is sown. The longer canola takes to emerge, the shorter the protection.
- Read more: Flea beetles take advantage of late seeding
A foliar insecticide is economic once about 25 per cent of the crop is defoliated, Manitoba Agriculture entomologist John Gavloski said in an interview.
Some farmers are feeling guilty they didn’t spray soon enough, but they shouldn’t, Brackenreed said.
“It really does happen that fast… particularly when stem feeding is happening,” she said. “I think the hot, dry, windy conditions we had exaggerated that.
“It’s also a good lesson. We have to really be on top of it and look at all areas of the field.”
Whole fields reseeded
“I am hearing quite a lot about reseeding, not just headlands, but whole fields and multiple spray applications occurring.
The other factor that’s a little strange and unique to this year is they are aggressively feeding on four- or five-leaf plants and they haven’t seemed to be able to grow through that.”
Usually when plants are that mature they can withstand flea beetle attacks, Gavloski said.
Both he and Brackenreed suspect damage is worse this year because of high populations.
“In my opinion I think a lot of what we’re seeing is a population that’s completely overwhelming that seed treatment,” Brackenreed said. “You need to have feeding for them to ingest the seed treatment. In this case there are so many of them the feeding was likely enough for economic damage.
Canola emergence was rapid in many fields this spring, which should mean longer seed treatment protection. But those same environmental conditions were good for flea beetle feeding, Brackenreed said.
“This spring when I was out before any canola was seeded I was seeing a lot of them. So they were waiting and pretty hungry. As soon as stuff came up they were ready to attack and start feeding pretty aggressively.”
Earlier canola seeding has seen an increase in striped flea beetles, she said. A little later the crucifer flea beetles started feeding. Some farmers sprayed and controlled the striped flea beetles, only to have fields decimated later by the crucifer type.
Unlike many crop-attacking insects whose populations rise and fall cyclically, flea beetle numbers are chronically high, Gavloski said.
“They seem to handle our winters quite well,” he said. “We’re not aware of any natural controls that really take the population down quickly.”
While some farmers are skeptical about the effectiveness of flea beetle insecticides, both Gavloski and Brackenreed say they work. There are no documented case of flea beetle-resistant insecticides, Gavloski said.
“I have a lot of faith in these insecticide seed treatments that we have,” Brackenreed said. “I know that farmers get frustrated and feel it’s not efficacious, but we didn’t have it we’d see just how efficacious it is.”
MASC has received 480 canola claims representing 118,000 acres this spring, but as of June 8 hadn’t broken out the causes.
To be eligible for a reseeding claim of 25 per cent of crop insurance coverage MASC must first determine the appraised yield will be less than the farmer’s probable yield or the 10-year average.
“Then the decision (to reseed) is totally up to you (the farmer),” Koroscil said. “We have fields where there’s nothing left, or very low (plant) counts, or it could be up close to your probable yield and you just want to re-seed and get the maximum yield that you can.”
Crop insurance deadlines for seeding canola varies with location and coverage.
The deadlines for full and reduced coverage in Canola Area 2 are June 10 and 15, respectively.
The deadlines in Canola Area 1 are June 15 and 20, respectively.