The summer population of flea beetles has emerged in large
numbers this year. Flea beetles are being observed in maturing canola
fields (North Central ND; Source: Brady Schmaltz, Arthur Companies),
Brassicas crops being used as cover crops (i.e., radishes) and in backyard
gardens. For canola, there is no established Economic Threshold for flea
beetle feeding injury on pods. Flea beetle feeding injury on pods is
usually most significant on late-planted canola and on the upper pods.
Fortunately, the lower pods of canola are the primary pods that provide
most of the canola yield. However, flea beetle feeding injury on pods can
result in poor seed fill, premature pod drying, or pod shattering. If the
canola is mature, pass the 5.2 growth stages (when seeds in lower pods
have turned translucent to green), then yield will probably be less
impacted by flea beetle feeding. In a flea beetle trapping study of freshly
swathed canola, the number of flea beetles per trap decreased
dramatically after 7-days of drying in swath. Flea beetles are mobile
insects and fly around to find ‘greener’ canola fields (late-planted) for
Insecticides registered for flea beetle control with a short, 7 day Pre-Harvest Interval (PHI) include: Delta Gold
(deltamethrin), Declare (Gamma-cyhalothrin), Warrior II and generics (lambda-cyhalothrin), and Mustang Maxx (zetacypermethrin).
Insecticides that are labeled to control flea beetles on canola are listed in 2018 North Dakota Field Crop
Insect Management Guide E-1143.