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Flea beetles feeding on canola leaves and pods are unlikely to cause an economic loss. Numbers have to be very high – perhaps 100 per plant – before economic losses occur…
Flea beetle
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If the tissue underneath the bite is still living, the seedling will likely survive as long as (1) the stem can still bear the weight of the cotyledons and first leaves, (2) the stem is not to subjected to more feeding, and (3) weather conditions are good for plant growth… -
Early-seeded and slow-growing canola crops (usually due to dry conditions) have faced more flea beetle pressure this year, particularly in Manitoba and central Alberta. Flea beetle emergence tended to occur before most canola crops had emerged, so flea beetles concentrated on the earliest fields. And because topsoil moisture levels were fairly low, these canola plants were growing very slowly. Concentrated… -
Synthetic pyrethroids (Decis, Matador/Silencer, for examples) benefit from late-day spraying because they should be applied when temperatures are below 25°C…
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Test your flea beetle knowledge with these five questions… -
With hot, dry conditions, canola seedlings already under pressure from intense flea beetle feeding dried out and died… -
Cool, windy, wet weather can delay flea beetle emergence. Peak emergence of the crucifer flea beetle occurs when ground temperatures reach 15°C, which is why perhaps it seems numbers are lower in many areas so far this year. They just haven’t come out yet in large numbers… -
A few flea beetles in a field are not worth the time and investment to spray. They will not cause economic losses. Only when defoliation reaches 25% across the field and feeding pressure continues does it make sense to spray for flea beetles…
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The economic thresholds – the point at which foliar insecticide provides an economic benefit – could be when damage reaches 50%, but leaf area loss can reach this stage fairly quickly when flea beetle numbers are high, they are actively feeding, and damage is already at 25%…
