format:blog · src:pplx+vertex ·

Bok Choy Pests 101: Cabbage Worms, Slugs, and Simple Barriers

Answer: Common bok choy pests include cabbage worms, slugs, flea beetles, and aphids. Simple barriers like row covers, hand removal, and good garden hygiene can help reduce damage without harsh chemicals.

Bok choy leaves with holes and a cabbage worm on a leaf
  • Use physical barriers early, especially on seedlings.
  • Avoid overwatering and dense planting to reduce pest pressure.
  • Do not rely solely on barriers if infestations are severe.
  • Always confirm pest identity before treating.

Common Bok Choy Pests

Bok choy growing under a floating row cover on hoops

Bok choy is a favorite among many gardeners for its crisp stems and mild flavor, but it’s also a magnet for several common pests. The most frequent troublemakers are cabbage worms, slugs, flea beetles, aphids, and sometimes cutworms or whiteflies.

These pests can chew holes in leaves, stunt growth, or leave behind sticky residue and frass (insect droppings). Many of them are especially active on young plants, so early protection is key.

According to the University of Arizona’s crop profile, pests like cabbage maggots and leafminers can significantly impact stand establishment and leaf quality in bok choy if not managed early in the season Source - University of Arizona.

Cabbage Worms

Slug feeding on bok choy leaf at night, showing slimy trail

Cabbage worms are the green caterpillars of cabbage white butterflies. They chew irregular holes in bok choy leaves and leave behind dark frass that can stain the foliage.

“Cabbage worms can quickly defoliate brassicas if left unchecked, especially on young plants,” says Dr. Mary Rogers, Extension Educator in Horticulture, University of Minnesota Extension Source - University of Minnesota Extension.

Signs of cabbage worms include:

  • Irregular holes in leaves
  • Dark green frass on leaves or in leaf folds
  • Green caterpillars, often on the undersides of leaves

Many gardeners find that row covers applied at planting time are very effective at keeping butterflies from laying eggs on bok choy Source - GardenersPath.com.

Slugs and Snails

Slugs and snails are soft-bodied pests that feed at night, leaving behind ragged holes and slimy trails on bok choy leaves.

They thrive in moist, shady areas and often hide under debris, stones, or dense plantings. Reducing their hiding spots can make a big difference.

Common signs of slug and snail damage:

  • Irregular, ragged holes in leaves
  • Shiny slime trails on leaves or soil
  • Pests found under leaves or debris at night

Keeping the area around bok choy clean and well-drained may help reduce slug and snail populations Source - GardenersPath.com.

Simple Barriers That Work

Physical barriers are often the first line of defense against bok choy pests. They’re simple, low-cost, and can be very effective when used at the right time.

Row Covers

Row covers are lightweight fabric sheets that sit over hoops or frames above the plants.

  • Install them right after planting or transplanting.
  • Secure the edges tightly with soil, rocks, or pins to keep pests out.
  • Use them to block cabbage butterflies, flea beetles, and some flies.

Row covers can reduce cabbage worm infestations by preventing egg-laying adults from reaching the plants Source - Mississippi State Extension.

Collars and Edging

For cutworms and some crawling pests, collars around young transplants can help.

  • Use cardboard, aluminum foil, or plastic cups with the bottom cut out.
  • Press the collar a little into the soil to prevent pests from crawling under.
  • These are especially useful for seedlings in the first few weeks.

Trap Crops

Trap crops are sacrificial plants that attract pests away from your main crop.

  • Plant mustard or radish near bok choy to lure flea beetles and cabbage worms.
  • Monitor the trap crop and remove or destroy it once heavily infested.
  • This can reduce pest pressure on your bok choy without chemicals.

Other Common Pests

Besides cabbage worms and slugs, bok choy may face:

  • Flea beetles: Tiny black beetles that make small “shot-hole” patterns in leaves.
  • Aphids: Small, soft-bodied insects that cluster on stems and undersides of leaves, sucking sap.
  • Whiteflies: Tiny white insects that fly up when disturbed; they leave sticky honeydew and can encourage sooty mold.

Many of these pests are more damaging to young plants, so protecting seedlings is often more effective than trying to control large infestations later.

Garden Hygiene and Culture

Good cultural practices can reduce pest pressure over time.

  • Rotate bok choy with non-brassica crops each season to break pest cycles.
  • Remove plant debris and control weeds that can harbor pests.
  • Space plants well to improve airflow and reduce humidity.
  • Water at the base to keep leaves dry, which may help reduce some pest and disease issues.

Healthy, well-grown bok choy tends to tolerate minor pest damage better than stressed plants.

Organic and Low-Impact Controls

When barriers and hygiene aren’t enough, many gardeners turn to low-impact options.

  • Hand-pick cabbage worms and slugs in the evening or early morning.
  • Use insecticidal soap or neem oil for aphids, whiteflies, and some caterpillars, following label directions.
  • Apply Bacillus thuringiensis (Bt) to young caterpillars; it’s specific to certain larvae and less harmful to beneficial insects.

Yellow sticky traps can help monitor for pests like flea beetles and leafminers, giving an early warning of rising populations Source - University of Arizona.

When to Let It Go

Even with good practices, some pest damage is normal. Minor holes in leaves usually don’t ruin the harvest, especially if the plant is otherwise healthy.

If a plant is severely damaged or stunted, it may be more practical to remove it and focus on protecting the rest of the crop. Sometimes, the best move is to grow bok choy as a fall crop, when many pests are past their peak activity.

Key Terms

  • Cabbage worms: Larvae of cabbage white butterflies (Pieris spp.), chew holes in brassica leaves.
  • Frass: Insect droppings, often seen as dark specks on infested leaves.
  • Row covers: Lightweight fabric barriers that exclude flying and crawling pests.
  • Trap crop: A sacrificial plant used to lure pests away from the main crop.
  • Bacillus thuringiensis (Bt): A microbial insecticide that targets caterpillars.

FAQ

How do I tell cabbage worms from other caterpillars?

Cabbage worms are usually pale green with faint yellow stripes and move slowly. They’re often found on the undersides of leaves. Other caterpillars may be hairier, more colorful, or move differently.

Are row covers safe for bees?

Row covers exclude all insects, including pollinators. For bok choy, which is harvested before flowering, this is usually not a problem. Remove covers if you plan to let the plant flower for seed saving.

Can I eat bok choy with holes?

Yes, bok choy with minor pest damage is usually safe to eat. Wash it well and remove badly damaged parts. Avoid eating leaves covered in frass or sticky residue if you’re uncomfortable with it.

Safety and Sources

This guide is for general gardening information and is not a substitute for professional pest management advice. Always identify pests correctly before taking action, and follow product labels if using any sprays or treatments.

For more detailed, region-specific guidance, consult your local cooperative extension service or agricultural university resources.

Leave a comment

Back to Agritourism