It is crucial that fields are scouted thoroughly and often. A heavy infestation on a stressed or thin stand can do significant damage in 24 to 72 hours. Be prepared in case additional control measures are required. The economic threshold for flea beetle control is when 25% or more of the cotyledons are damaged. However, if frost has already damaged some of the leaf material or thinned the stand, the action threshold may need to be adjusted. Evidence of feeding does not automatically mean spraying is warranted. Unwarranted spraying can cause harm to beneficial insects and can also contribute to the development of insecticide resistance. With current seed treatments, flea beetles must feed on leaf material and ingest the insecticide for control so some leaf pitting is normal. Flea beetles make their way into canola crops from the edges of fields. By catching a problem with flea beetles early, producers can often spray the perimeter of their fields and stop the infestation before it becomes widespread.
The following link provides more information on flea beetles:
The following links provide information on foliar insecticide flea beetle control in canola: