What to do now about flea beetles

Marissa Schuh, Horticulture IPM Extension Educator

Flea beetle continues to be one of the biggest pests on Minnesota vegetables farms, especially in our brassica crops.

Flea beetle damage on mustards. Whitney Cranshaw, Colorado State University, Bugwood.org

Quick refresher on some key things to think about with flea beetles this time of year.

• The larger the crops are, the more resistant they are to feeding (though they do often feed on what we are hoping to sell). Solanaceous crops are getting to the point where flea beetle feeding matters less.
• Kaolin clay can provide a physical barrier to feeding (but doesn’t always work, and isn’t a good fit for leafy brassica greens)
• Some growers feel beneficial nematode introductions have been helpful in bringing populations on their farms down. University research trials on flea beetles and nematodes have been mixed.
• If 10-20% of the leaf area of plants are damaged, consider spraying
• Flea beetle damage may be concentrated at the edges of the field or in hot spots in the field. Spot treatments can sometimes be effective while saving time and money.
• For conventional pesticide options, see the Midwest Vegetable Production Guide.
• On the organic side, product performance is mixed.  Pyrethrin and spinosad products have performed the best, but even then, they often don’t give great control. There have been some recent reports on organic products in the release pipeline, so hopefully some more organic pesticides will become available in the coming years.

There are also cultural controls that could be implemented in the future years.

The lifecycle of the crucifer flea beetle. Illustrations by Martha Sudderth. Created with BioRender.com by Marissa Schuh.