Flea Beetle in Spring Canola: Monitor, Identify Fields at Risk & Consider the Weather

Jun 03, 2020

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Canola producers are likely familiar with flea beetle and have an understanding of how to manage them. Many are reporting flea beetle feeding this spring.  A few resources have been brought together here to help with scouting and decision making on control measures.
  • “Five Things to Know about Flea Beetle” from Canola watch by Canola Council of Canada (CCC)
  • Comprehensive Flea Beetle Info: life cycle, integrated pest management from CCC

Monitor

Once you notice flea beetle in the field, monitor it daily or as often as possible because they advance quickly. Expect to see some feeding damage, as flea beetles must take a bite to die from seed treatment. It is important that you do not spray too soon. Early application won’t protect a field from re-infestation.  Flea beetles are strong fliers and can quickly re-infest a field.
 
Control is generally warranted when there is 25% of the surface leaf area damaged.  The economic threshold is 50% defoliation but intense feeding can quickly take 25% damage to 50%, so 25% is used as the action level.
 
Fields at the Greatest Risk
 
Fields with thin stands of less than 5 plants/ft2 or where flea beetle are feeding on stems or new growth should be prioritized in terms of scouting and taking action if needed. Stem feeding is less common but will cause greater damage than feeding on cotyledons. A stem chewed right through is 100% feeding damage. Likewise, feeding on the growing point can have a greater impact on crop development. Healthy stands that are growing quickly may not need to be sprayed, and canola can typically outgrow flea beetle damage once it reaches the 4-leaf growth stage.
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