Canola School: Use a bird-like approach to scouting for bertha armyworm

(Canola Watch/Supplied)

Bertha armyworm isn’t necessarily an insect pest the Prairies have had huge amounts of trouble with over the last few years.

Which is exactly why it may be our turn for an “on” cycle, says Keith Gabert of the Canola Council of Canada.

If there are bertha armyworm in the field, it’s important to get control of them early — the future crop will thank you.

“You want to keep your leaves, and have them actively filling those pods for you,” explains Gabert, in the Canola School below. Even if the berthas don’t eat all your leaves, there’s a chance all those leaves are going to become roughly inedible, and they’re going too move up onto the pods anyways.”

Typically, Gabert says he uses 20 of the insects per metre squared as a threshold, but this will tend to sway a little either way, depending on commodity prices and where the canola is at.

The key to scouting for bertha armyworm, says Gabert, is not as easy as one may think, as you essentially need to go into the field and pretend you’re a really big bird.

“You come into the field, you shake out a bunch of canola — a metre squared — you let all those insect worms drop onto the ground. I would then pick up the dried leaves, anything on the base of the ground, just pick them up in the first few seconds. And then sit back to a minute or two and watch, because these insects are relatively smart. They know something just tried to get them, and they don’t move,” he explains.

“If you give them a minute or two, you’ll see them start to relax and start to uncurl from that tight sort of ‘c’ shape they were in, and then you’ll count them. Often if you don’t do that, you’ll miss half of them.”

Check out the full Canola School video below for a conversation on trapping, leaf feeding, and indications of bertha armyworm, below:

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