Canola pest | 2013 saw an expansion of the pest north of the South Saskatchewan River
Some insect pests are projected to be on the decline this growing season, but others need to be closely monitored, said an insect control specialist.
It’s reasonably good news overall, said Scott Hartley of Saskatchewan Agriculture.
“Cabbage seedpod weevil is one that is becoming a real up and coming pest in the province,” he said during an integrated canola pest panel discussion at CropSphere in Saskatoon, which was held as part of the Crop Production Show that ran Jan. 13-16.
“A good amount of their life cycle can be detrimental to canola crops.”
Read Also
Farming Smarter receives financial boost from Alberta government for potato research
Farming Smarter near Lethbridge got a boost to its research equipment, thanks to the Alberta government’s increase in funding for research associations.
The pest has been migrating east and north from southwestern and south-central Saskatchewan since 2000.
Like the flea beetle, it over winters as an adult and starts feeding and flying once temperatures warm up to 12 C.
Hartley said the weevils are edge feeders that gradually spread into the crop.
They lay their eggs in the developing pods and the larvae grow and emerge from the pod. They then pupate in the soil and start feeding again in the fall.
Hartley said 2013 was a banner year for the insect.
Higher numbers than ever seen before were observed in Sask-atchewan with a major expansion north of the South Saskatchewan River.
On the other hand, the diamondback moth wasn’t a problem last year, thanks to a late spring of cool weather.
Wind trajectories typically play a significant role in bringing the pest north from Mexico and Texas. Not as many wind currents last year brought them in from April to the end of May.
Last year followed an especially bad year for both the diamondback moth and the aster leafhopper. Wind currents carried them in at high numbers.
Both insects are also capable of some degree of overwintering.
“This past winter … I don’t think will be very favourable for overwintering. Therefore, those wind currents become a lot more important for bringing the pests into the province,” he said.
Hartley said the bertha armyworm has already started to fizzle out, according to feedback from pheromone bated survey traps.
“I think the (insect) is one of the better news ones,” he said.
Numbers will remain high this year but are trending downward, as the worm is biologically controlled through parasites, disease and viruses, he said.
Traditionally, grasshoppers have not been a big issue with canola.
“When they have been a big problem with yield is when they are feeding on canola pods,” he said.
“Although we did see high numbers into the fall (embryo development) this last year, grasshoppers don’t appear to be of high risk for most of the province in 2014,” he said.
Hartley describes Swede midge as “an up and comer,” with infestations increasing.
The year 2012-13 was the first time it was seen in high numbers, particularly in northeastern Saskatchewan.
He said the insect is generally found in crop perimeter areas and favours high moisture. The mild winter of 2011-12 was also a contributing factor, combined with its existing populations.
The problem is with increasing generations, and Hartley said there are at least three now in the province. Research indicates it’s a concern at or before bolting because it affects the growing point.
Glued together flowers that form a lantern shape are a telltale sign that larvae are inside.
“For sure, you know you’ve got it if those flowers are split apart and you can actually see the larvae in them. Ultimately the florets die and turn brown,” he said.
Research is expected to get underway this year. However, “There’s not a lot of good answers for the Saskatchewan situation at this point.”
