Flea beetles: When to spray?

May 11, 2016 - Issue 8

Flea beetles are feeding on volunteer and early-seeded canola but their presence does not mean they need to be sprayed. Seed treatments will provide 3 to 4 weeks of protection for canola that emerges within a week of seeding. But scouting is still necessary early in the season to make sure the seed treatment provides enough protection.

Flea beetles have attacked the leaves and stem of early canola seedlings. Credit: Keith Gabert

Flea beetles have attacked the leaves and stem of early canola seedlings. Credit: Keith Gabert

Here’s why:

1. Flea beetles need to take a bite of the plant in order to take up the insecticide, so there will be some feeding even while the seed treatment is working. But in some cases, intense nibbling by a very large flea beetle population could overwhelm the seed treatment.
2. In slow growth scenarios, seed treatments may lose their protective ability before plants are large enough to tolerate much feeding.
3. The two most common seed treatment insecticides may be a bit less effective on striped flea beetles, so check which one is most common in your field. Most areas of the Prairies have both striped and crucifer flea beetle species.

Further reading:

8 steps to make the flea beetle spray decision
5 things you need to know about flea beetles

Canola Watch