An above average concentration of the bertha armyworm moth in the County of Stettler has officials warning producers to check their canola crop before it hurts their bottom-line.
The number of bertha armyworm moths is increasing at rapid rates at collection site in canola fields throughout the County of Stettler, and Jay Byer, county assistant director of agricultural services, is concerned about a damaging outbreak of the pest.
“Even last year when we had a somewhat patchy infestation we did have some fields that saw 20 to 30 per cent damage,” said Byer. “People need to be aware and go out and start checking their fields on a regular basis to make sure the risk of bertha armyworm moth infestations are low.”
The average collection count at sites near Erskine Monday were at 250 moths per trap, an increase of 400 per cent since the county’s last count.
Though the average at their sites is 250 moths, they have some traps with more than 300, one of the few places in Alberta to record such high numbers of the pest.
“That’s our tipping point, that’s when we start getting concerned about the numbers,” said Byer. “It looks like the numbers are rapidly increasing.”
Byer said the bertha armyworm moth tends to go in cycles in their area where they’ll have years with a high presence of predators who feed on the pest. This will take care of the problem for a few years. But then as the bertha armyworm moths die off then the predators die off as a result and the cycle continues and the numbers of the bertha armyworm moth starts increasing.
In terms of prevention, Byer recommends good crop rotation and not planting canola on top of canola.
“There is an over-wintering population,” said Byer. “The less back-to-back canola there is, the more likely we are of the moths having to at least travel and fly to the next field.
“Another method of trying to minimize risk is spreading out the seeding date of canola. If they start real early and then have some canola staged in over time the field that is ideally suited for bertha at the time they’re starting to fly might attract them, but the others might not.”
Producers should go out and check their fields over the next week or two and investigate several sites. Take a one-squared metre sample and beat all the plants around to drop all the bertha armyworm moths to the ground.
“They’ll have to determine, with their crop professionals, whether or not the number of berthas they see is more than the cost of spraying and whether it is economical to do some control on them or just bare the brunt of some damage to their crop,” said Byer.
mcrawford@www.reddeeradvocate.com