Flea beetle spraying can be emotional decision

Spock from Star Trek would have been a good farmer.

He’s famous for being logical and removing emotion from every decision.

But Spock isn’t human.

Humans are emotional creatures, and feelings can drive decisions.

That’s why it’s hard for canola growers to watch flea beetles devour the leaves on tiny canola plants in late May and early June. Growers are emotionally and financially invested in the success of their canola crop, which is why applying a foliar insecticide to control the flea beetles can become an automatic decision.

The economic threshold for flea beetle damage is 50 percent defoliation, but the Canola Council of Canada recommends spraying at 25 percent because damage can quickly go from 25 to 50.

However, it’s hard to identify 25 percent damage when it’s your canola crop.

An independent, non-invested person might see 10 percent defoliation. For the same crop, the grower might rate it as 30 percent.

“The joke I use that sums it up really well is, ‘you should let somebody else decide the percent defoliation because if it was your crop, you would spray at 10 percent,” said Keith Gabert, a canola council agronomist in Alberta.

The first two weeks of June are usually associated with the highest levels of flea beetle feeding in Western Canada.

Gabert, who participated in a conference call with other canola council agronomists June 2, said there are a number of regions where some farmers are applying foliar insecticides to control flea beetles, southern Alberta, southern Manitoba and northeastern Saskatchewan.

In Manitoba, flea beetles have been hard on earlier-seeded canola, which sat in the soil during the first half of May and emerged slowly. Canola seeded during the warm weather in the last week of May should be in better shape to fight off beetles.

“Mainly fields that were seeded early into cool soil … they were at greater risk,” said Manitoba Agriculture entomologist John Gavloski.

“The later seeded … we’re still quite hopeful that it can get to that three to four leaf stage before the (insecticide) seed treatment wears out. This coming week it’s supposed to be good temperature-wise and if the soil moisture holds up, the fields might be able to make it with just the seed treatment.”

However, there are many cases every spring where foliar spraying is necessary. The decision should be based on an economic threshold, but it’s hard for growers to remain detached and unemotional, especially early in the growing season.

“Growers are really sensitive to the use of foliar insecticides. Many of them would like to avoid their use. But flea beetles are a little different than the other insect pests that they deal with,” Gabert said from his home in Innisfail, Alta.

“It’s happening at a time when your crop is quite small, and in some cases it’s kind of like a mother with her first child. I have four kids. We treated the fourth probably a little differently than the first.”

Put another way, parents will buy a $350 car seat to make sure their first child is safe. By child number three, a used car seat — stained with apple sauce and sour milk — is good enough.

Producers might make a different decision regarding foliar sprays for flea beetles if they can be aware of their psychology and the associated feelings.

“The urge to grow a good crop is so strong in spring, it makes it even more difficult to manage a (pest that’s causing visual damage),” Gabert said.

“A cotyledon canola plant that has a few bites on it, where the defoliation is … objectively 10 to 15 percent removal of the leaf material, it looks like it’s really suffering. It really does.”

As well, growers might have heard a story from a neighbour who had 500 flea beetles per sq. foot or some massive concentration of the pest or could have gone through a difficult harvest in 2019.

That recent memory can affect decisions this spring.

“If a grower didn’t get harvest done last fall, he’s thinking, ‘what if this (flea beetle pressure) delays my crop? I can’t afford for this crop to be thin and late,’ ” Gabert said.

Given all the psychological and emotional factors, it’s challenging to make a Spock-like decision about foliar spraying. That’s why looking at canola leaf damage objectively is critical piece of analysis.

“Nothing replaces boots in the field,” Gabert said.

“Ten or fifteen percent (defoliation) looks bad, but take your time and assess multiple areas in the field…. If you approach this problem the same as you would any other and make a calm, cool and collected decision, you would probably spray less for flea beetles.”

That said, remaining calm about a crop that pays the bills is not easy.

A 55 bushel canola crop can be a financial saviour for many farmers.

“If things work out and if you can nurture this crop along, the potential returns are really good,” Gabert said.

“So, they have a lot of expectations riding on that crop.”

Contact robert.arnason@producer.com

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