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Summer Flea Beetles Feeding on Canola Pods (08/02/18)

The summer population of flea beetles has emerged in large numbers this year.

Summer Flea Beetles Feeding on Canola Pods

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 summer feeding.

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 (zeta-cypermethrin). Insecticides that are labeled to control flea beetles on canola are listed in 2018 North Dakota Field Crop Insect Management Guide E-1143.

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Janet J. Knodel

Extension Entomologist

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