Bertha armyworm, wheat midge warning issued

Bertha armyworm is expected to be a problem in southern Alberta, while wheat midge is a concern in central region

RED DEER — Producers in southern Alberta might experience an influx of bertha armyworms this year, while those in the central region could experience higher wheat midge populations.

The predictions should be taken with a grain of salt given much can change, said Alberta insect management specialist Scott Meers, but he added producers should still be on the lookout for headache-inducing pests.

“I’m about 20 percent accurate, so take it for what it’s worth,” he said jokingly to the audience while speaking Jan. 7 about his outlook during the Agronomy Update conference in Red Deer.

“I’m almost as good as the weatherman.”

Still, if Meers predictions turn out to be accurate, farmers are going to need to implement a number of management practices to deal with pests.

With a potential spike in bertha armyworm populations in the south, producers there might have to use insecticides early to avoid widespread crop losses. Failure to detect infestations early could result in insufficient time to apply the chemicals before severe damage is done.

A potential spike in bertha armyworm populations in southern Alberta means producers there might have to use insecticides early to avoid widespread crop losses. | MAFRI/John Gavloski photo

Meers predicted producers in central Alberta likely won’t have to spray for bertha armyworms. Farmers in the Peace region likely have one more year of spraying, he said, suggesting the pests could be less intense there.

As for wheat midge, Meers said it’s on the rise in central Alberta. It’s caused significant damage to crops in recent years.

Producers are advised to grow varieties that are tolerant to wheat midge. | File photo

He recommended producers there move to growing a midge-tolerant wheat.

The wheat midge forecast in the Peace is low, he said, but it could still turn up in individual fields. He recommended producers scout for it, saying the best time is just before swathing.

No wheat midge is predicted for southern Alberta, he added, because the region tends to be dry. The midge like it wet.

Other insect pests producers should always be on the lookout for include flea beetles, diamondback moths, cabbage seed pod weevils, cutworms and wheat stem sawfly, among others.

Flea beetles are a persistent problem, Meers said, adding that some management practices might be making the problem worse, though the biology of the insect isn’t helping.

“Stripe flea beetles are making our life a little bit of hell right now and it’s a little bit of what we are doing and bit about the biology of that insect,” he said. “We have to understand it’s an insect that comes out earlier, is more tolerant of our insecticides, it feeds more aggressively, and makes more babies so it’s more of a problem.”

He said lighter seeding rates, as well as early seeding, could be putting the canola crop in a situation that makes it easy for the flea beetles to feast.

“We have to think about seeding rate and date. I’m not saying you need to change them,” he said. “I think what you’re doing is right given conditions. Seed is expensive and there are bigger yields if seeded earlier, but we’re playing into the hands of this insect.”

With diamondback moths, Meers said scouting at the early flower stage will be key to get a sense of what is expected for the rest of the season.

The insects come via flight and don’t overwinter in Alberta, and Meers said it’s hard to predict whether their numbers will rise.

As for cabbage seed pod weevils, Meers said southern Alberta usually has near threshold levels during early flowering in canola. If there is a lot of them, the second-tier flowering stage also gets to threshold levels.

He said producers south of the Trans-Canada Highway are likely going to need to spray at the first-flowering stage.

The pest usually has a hard time with cold winters, so areas north of the Trans-Canada won’t need to watch as closely. It’s surviving north of that area, but not thriving.

He said farmers in southern Alberta should pay attention to glassy cutworms again. It has been doing major damage to timothy hay stands, Meers said.

In the south, producers should also be on the lookout for wheat stem sawfly. It likes dry weather.

Meers said it’s on the rise in southern Alberta and growers have been asking for better hard red spring wheat varieties with a solid stems.

Parasitism hugely affects sawfly populations, he said. Bracon cephi, a native braconid wasp, is the only insect in Alberta that researchers know of that eats the pest.

He pointed to a survey that found producers with a stripper header managed to have fewer sawfly issues because bracon cephi overwinters in the stem. Producers who ground up the entire crop through the combine essentially ground up the beneficial wasps with it.

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