Why Are Slugs Eating Holes in My Beetroot Roots?

Discovering neat, round holes or irregular cavities in beetroot roots, often extending several centimetres into the root body, is the work of slugs feeding on the root from outside or underground. The large, dark keel slug (Milax gagates) is particularly associated with underground root damage — it feeds primarily below soil level, tunnelling into the roots of beets, potatoes, and other root vegetables without the slime trail that normally betrays slug presence. Surface-active slugs also feed on the exposed crown of beetroot, which sits above soil level as the root matures.

Identifying slug damage on beetroot

Slug damage produces clean-edged holes or cavities with a smooth, slightly glistening surface where the slug's rasping teeth (radula) has removed tissue. The holes may extend into the root or be limited to the outer surface. Examine closely for slime trails on the root surface or in the cavity — these confirm slug activity. Wireworm damage (by soil-dwelling beetle larvae) is also possible in root vegetables and looks similar but is typically in narrower, straighter tunnels; wireworm cavities are dryer and less smooth-edged than slug cavities.

Managing slug pressure on beetroot

Iron phosphate slug pellets applied around the beetroot bed at the label rate are effective and safe for soil organisms. Nematode biological control (Phasmarhabditis nematodes) applied to the soil in late summer specifically targets the underground keel slug and dramatically reduces root damage in problem soils. Harvesting beetroot when it first reaches usable size (5–7 cm) rather than leaving it in ground reduces the total exposure time. In high-pressure soils, growing in raised beds with fresh compost rather than garden soil largely avoids the established slug populations that cause the worst damage.

Is slug-damaged beetroot edible?

Yes — cut out the damaged area with a clean knife, cutting well past the cavity margins, and the rest of the root is safe to eat. However, roots with large or deep cavities deteriorate quickly because the exposed tissue is a site for secondary fungal and bacterial infection. Use damaged roots immediately rather than storing them.