Canola School: Mitigating flea beetle damage through uniform seeding

Flea beetle diagram by Jack Payne (Kara Oosterhuis/RealAgriculture)

When talking about flea beetles and flea beetle pressure, it’s really all a numbers game. How can we get the least amount of insects across a wide range of plants?

The key, says Jack Payne of South Country Co-op, is uniform seeding and emergence. Getting canola crop off to a quick and even start will pay dividends in many situations — especially when looking at mitigating flea beetle pressure.

“What I saw last year in some of the fields that were heavily injured through flea beetles, was when we started digging around, we found seed that was less than a half an inch deep. And we were also finding seed that was down to two-inches, or more deeper,” he explains, which creates a situation where there are almost two emerging crops of canola.

“The shallow seeded canola emerges first, because it’s got less distance to travel. So if you’re shooting for seven to eight plants per square foot, if only half of them emerge, you’ve got three to four come up initially,” says Payne. “The flea beetles then go, ‘woo, okay, the buffet is open,’ and they overwhelm those three or four plants per square foot. And that’s what we saw last year — some of the first canola that came out of the ground was just completely overwhelmed with flea beetles. ”

A few days later the rest of the canola emerged, creating this second wave, which the flea beetles were then able to attack as well, after they had already decimated the first wave. Twenty flea beetles spread out between eight plants results in a much-reduced damage level than twenty beetles spread over just three plants.

What we do in terms of crop establishment can ultimately have an impact on whether or not we’re going to have to spray for the insect pests, so as Payne explains, saving money on seed costs may not be the right answer.

“If you’re targeting low plant population on purpose, you’re on that low end of four-to-five plants per square foot… yes, that will make a viable crop, but you might already think I need to scout that field for flea beetles, because if anything goes wrong in terms of establishment, cold weather, anything like that, the numbers could overwhelm those plants.”

Check out the full conversation in the Canola School episode, below:

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