Flea Beetle Management in Cole Crops

Adult flea beetles will feed on many cole crops' cotyledons, leaves, and stems. Feeding injury can be significant at times and may result in uneven stand development in some fields. Flea beetle injury is frequently observed on cole crops like cabbage, broccoli, cauliflower, collards, kale, turnips, and tatsoi. Flea beetles are approximately 2–4 mm in length, and their enlarged rear legs allow them to jump long distances to escape predators and move deep into vegetable fields.

Cole crops are most vulnerable to flea beetle damage after transplanting. Growers should treat newly transplanted cole crops when flea beetle populations reach one beetle per transplant or 5 beetles per 10 transplants during the cotyledon stage.

In the summer, flea beetle females begin laying eggs in the soil adjacent to "food" plants or on plant tissues. After the eggs hatch, the brown-headed, white larvae feed on plant roots before pupating in the soil. Depending on your farm's geographic location, we usually observe 1–2 generations of flea beetles per year in Pennsylvania.

Flea beetles overwinter as adults in crop debris, hedgerows, windbreaks, and wooded areas that lie adjacent to vegetable fields. In early spring, untilled fields, pastures, and waste areas become awash with color when cruciferous weeds like yellow mustard and yellow rocket begin to bloom. These cruciferous weeds are often the first feeding targets for adult flea beetles.

Organic Management Methods

Crop rotation and destroying crop residues after harvest are critical in suppressing flea beetle populations. Other field sanitation methods, such as mowing and eliminating weeds (especially cruciferous weeds such as mustards and wild radish), can reduce hiding spots for the pest.

Floating row covers exclude flea beetles from your crop. Put the row covers in place before flea beetles have emerged. Secure the row covers so insects cannot get inside and feed unchecked.

Biological pesticides containing Beauvaria bassiana strains GHA or ATCC 74040 may reduce flea beetle populations. B. bassiana is a naturally occurring fungus that causes infection in insects, and some formulations are organically approved. 

Surround is a kaolin clay product that can be applied to young transplants to make the plant less favorable for the beetle to feed on.

Chemical Control Options

Before selecting and using any insecticide on your farm, please take the time to review the pesticide label and observe all precautions. Pesticide labels change regularly, and the law requires that you adhere to them.

Many pyrethroid (group 3A) and neonicotinoid (group 4A) insecticides are labeled for use on cole crops. Entrust (group 5) is OMRI-approved and is labeled for the suppression of flea beetle. Torac (group 21A) and diamides (group 28) Harvanta 50SL, Exirel, and Verimark are other options.

Refer to the Cole Crop chapter of the Mid-Atlantic Commercial Vegetable Production Guide for more chemical recommendations.