Most gardeners appreciate the importance of good crop rotation practices, but even these arent perfect.

For instance, this is the first season for our community gardens at Park Place Health Care Center in Great Falls, but it doesnt mean the pests still cant find the veggies. My friend Deb is having a hard time with the flea beetles eating her cruciferous vegetables.

Flea beetles are fast-moving, fast-jumping little pests are quick to disappear when disturbed, making them difficult to visually study. If you do see them, theyre only 2 mm long with hard shelled, dark bodies. Even if you dont spot them, if you have tiny shotholes in your broccoli, cabbage or Bok choi, and the culprits jump out of sight when you examine the leaves, you have a pretty solid case for flea beetles.

Protect Cole Crops with Floating Row Covers

Early in the season, it helps to protect cole crops with floating row covers. (This also keeps the cabbage butterflies off of the cabbage and broccoli.) In the garden, its also beneficial to plant trap crops, such as deacon or other radish varieties, every foot or so in the row.

When given the option, the flea beetles like these crops better than just about everything else so theyll concentrate on the radishes instead of your other veggies. Mustard and collards are also good options to tempt the beetles away from the main crops. Plus, it centralizes the flea beetles in case you want to dose them with organic or synthetic insecticides.

Diatomaceous Earth and Insecticidal Soap for Flea Beetles

You can also sprinkle the base of the plants with diatomaceous earth to discourage the flea beetles from dawdling, as well as eliminating the larvae that will eat the root hairs of the plants. Refresh it after a rain or heavy dew to ensure its effectiveness.

Insecticidal soap works okay, but it appears a combination of rotenone and insecticidal soap works much better. Other gardeners report decent effectiveness using a garlic spray (crush 6 cloves or garlic in a quart of water) or capsaicin. Of course, all of these topical treatments need to be reapplied on a regular basis partly since they might wear off from rain or overhead watering, as well as the flea beetles tendency to re-colonize. This means you might have scared off the initial bunch munching your cruciferous crops, but it doesnt mean a new one cant move in to the area.

When youre growing vegetables for their leaves, its pretty discouraging when flea beetles make them look like someone blasted them with a little shotgun. It doesnt leave much left for you to enjoy. Since Deb likes her cruciferous veggies, well have to have her in another plot next year to prevent the flea beetles from invading her crops, and will have to be vigilant for the other gardeners so they dont have holey plants.