When it comes to pest insects, producers are dealing with an “unprecedented” number of cabbage seedpod weevils this year.
Originally from Eurasia, the invasive insect was first found in southern Alberta in the late 1990s and made its way into Saskatchewan shortly after. The cabbage seedpod weevil continues to spread north and east and has now been found as far as Manitoba.
Provincial entomologist Dr. James Tansey said they are currently in the middle of surveying for the pest, and they have never seen populations this high or as damaging to canola crops.
“The adults can cause bud blasting, especially if conditions are hot, by feeding directly on the developing flowers,” said Tansey.
“But the larvae are really the economic stage for these ones. What’s going to happen is the females will chew a little hole in the developing pod — when it’s about three-quarters to one inch long — lay a single egg inside, and the developing larva will consume three to five seeds within that canola pod.”
Tansey said work is underway on developing resistant germplasm for cabbage seedpod weevil. Dr. Boyd Mori at the University of Alberta is currently testing a resistant line, which is not yet commercially available, but early field testing has shown promise.
“Part of the problem is that it’s such a sporadic pest. Once again, this year’s population is pretty unprecedented — full stop. So, making varietal choices based on a sporadic population can be problematic,” Tansey said.
He added there have been no major reports of spraying for grasshoppers at this time.
While hot and dry conditions are favourable for grasshoppers, last spring’s wet weather led to an outbreak of a fungal infection known as Entomophaga grylli, or “summiting disease.”
“That forces the grasshopper to climb to the top of the plant, grab on for dear life and die. Then it’s going to rain down fungal spores on all his friends,” said Tansey.
He noted that grasshoppers don’t seem to be a major problem this year, but they are capable of flying more than 100 kilometres per day and can migrate if local hotspots become depleted.
Currently, producers are facing more issues with canola pests such as diamondback moths and bertha armyworms.
Gophers are also a concern, especially in the southwest and south-central regions of the province.
Tansey said field testing took place in 2022 and 2023 for alternatives to strychnine, which was deregistered for use on Richardson’s ground squirrels (also known as gophers). Testing showed positive results with zinc phosphide products.
However, there is speculation that those results are not holding up this year, possibly due to storage issues — zinc phosphide can break down under high temperatures and moisture.
Tansey added that anticoagulants similar to warfarin have also shown promise, although they can take seven to 10 days to be effective.
There have been reports of large numbers of pea aphids from producers getting their first cut of alfalfa hay. Tansey said aphids were a severe issue last year, and evidence is emerging that they may be developing resistance to Group 3 insecticides, such as Silencer, Zivata and Matador.
A field testing kit has been developed to test the sensitivity of pea aphids to Group 3 insecticides.
While no spraying has been reported yet, Tansey said he expects to start hearing of applications in the next couple of weeks.
Field testing kits for pea aphids are available to producers and agronomists by contacting Tansey directly.