The province’s farmers are warned to be particularly watchful for bertha armyworms, flea beetles and pea aphids
Bertha armyworms, flea beetles and pea aphids are the three insect pests most likely to create problems in Alberta this year.
Bertha might be especially big.
“This one for me is the big warning in 2019,” said Scott Meers, an insect management specialist with Alberta Agriculture.
“I fully expect that we will have outbreaks in Alberta.”
Meers is among those who monitor and compile insect data through the Alberta Insect Pest Monitoring Network, and he gave an overview of his findings Jan. 15 at the Agronomy Update event in Lethbridge.
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Maps on bertha armyworms, cabbage seedpod weevils and grasshoppers were released last week, and maps on wheat midge, wheat stem sawfly and pea leaf weevil were made available online in December.
Meers said there are clear indications of bertha south of the Trans-Canada Highway as far as Vulcan. Outbreaks are likely in areas where there is snow cover, but the lack of snow in Alberta’s deep south might prevent major populations if that condition persists.
Cold weather can kill bertha pupae if there is no insulating snow cover.
Farmers around Red Deer and north should pay attention to the live bertha reporting that is done once the growing season starts. Meers also said bertha could be a problem in the Peace River region, intensifying from 2018.
Striped flea beetle has made its way south to Calgary, Brooks and Strathmore, said Meers.
“This insect is coming to a field near you.”
Striped flea beetles are different from the crucifer type more commonly seen in southern Alberta, and they may become predominant. That will require farmers to be more aggressive with foliar sprays.
“You will have to pay closer attention. We find that they are causing us grief in areas we haven’t seen them before.”
As for pea aphids, Meers said the mild winter so far, coupled with high numbers at migration, have put the south in a perfect situation for problems this year. Weather for the rest of the winter will be the determining factor.
There is good news in the insect pest outlook.
Meers said cabbage seedpod weevil numbers saw a bit of resurgence in 2018 from the lows of 2017 but no problems are expected from Red Deer north. The weevils often expand their range when winters are mild, so scouting, as always, will be the best way to determine action.
As for the pea leaf weevil, 2018 had the lowest population levels since the survey began. That raises questions about whether it is worthwhile this year to treat seed against the pest. Meers said he doesn’t know that answer.
“If you don’t seed treat, you’re going to be really tempted to foliar spray (if a problem arises) and you’re going to waste your money,” he said, because production losses from the weevil can’t be recovered by foliar spraying.
Producers will have to assess their risk, which so far appears low along the Alberta-Saskatchewan border.
Pea leaf weevils were found in the Peace River region in 2018, an expansion of its range.
“(However), the only good weevil is a dead weevil,” said Meers.
The monitoring network does not make forecasts for diamondback moths, but it does track early spring flight. Numbers were low in 2018, but there are no 2019 predictions.
“What I want for you in southern Alberta to pay attention to with diamondback is the early flower monitoring you do for cabbage seedpod weevil,” he said.
“Note what you’re seeing for diamondback moth at that point because that will be a better early warning than our monitoring with pheremones.”
Diamondback moths do have a number of natural enemies, among them a parasitic wasp.
“These things are in our canola every year,” he said.
“Last year they were in big numbers but every year, they are there, and … if we don’t have to spray and we are spraying, we may actually be working against ourselves.”
Wheat midge numbers are low, said Meers, especially in southern Alberta, so they are not expected to be a concern south of the Trans-Canada.
“(Further north), it’s going to be very much a field to field situation.”
Wheat stem sawfly increased its range last year, but numbers are largely weather driven so that will determine impact.
The grasshopper outlook is relatively benign, Meers said. Southern Alberta might be on the verge of an outbreak and areas of the Peace might also see problems.
