Rutabaga Pests and Diseases and How to Control Them Naturally

ByStephen Albert

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Rutabaga grows slowly through fall and early winter, making it vulnerable to pest pressure early on and moisture-related diseases later. After decades of gardening year-round in Sonoma Valley—with plenty of trial, error, and refinement—I’ve learned that a few consistent, natural practices keep rutabaga nearly pest-free and disease-free.

Here’s what to watch for and how to keep your rutabaga patch thriving.

🐛 Common Rutabaga Pests (and Natural Controls)

1. Flea Beetles

Symptoms: Tiny round “shot holes” in young leaves; stunted seedlings.
When they appear: Early fall when weather is still warm.

Natural Control

  • Floating row cover from sowing until weather cools.
  • Interplant herbs like thyme or sage to confuse pests.
  • Moist soil + light mulch to reduce dust—flea beetles prefer dry conditions.

My experience: Row cover is the only guaranteed solution for early fall. Once nights cool, I remove it.

2. Cabbage Loopers & Imported Cabbage Worms

Symptoms: Ragged holes in leaves, green frass (droppings), small green caterpillars.
When they appear: Mid–late fall if moths are still active.

Natural Control

  • Hand-pick daily (easier in cool weather).
  • Use row cover early in the season.
  • Apply Bt (Bacillus thuringiensis) if pressure is high—it’s organic and targeted.

My experience: Once November arrives, caterpillar pressure drops sharply in Sonoma Valley. Early protection matters most.

3. Root Maggots

Symptoms: Sudden wilting, poor growth, blackened tunnels in roots.
Most common during: Cool, moist early fall conditions.

Natural Control

  • Plant under row cover from the start to block egg-laying flies.
  • Add alliums (garlic, chives, onions) along bed edges.
  • Keep soil evenly moist but not soggy.

My experience: After I began lining rutabaga beds with garlic, maggot issues nearly disappeared.

4. Aphids

Symptoms: Clusters of green or gray aphids on leaves and growing tips.
Season: Late fall warm spells.

Natural Control

  • Blast with water in mornings.
  • Release ladybugs if infestations expand.
  • Use calendula as a trap crop.

My experience: Calendula holds aphids so reliably that I grow it in every winter bed.

🌱 Rutabaga Diseases (and How to Prevent Them)

1. Clubroot

Symptoms: Swollen, distorted roots; stunted plants.
Cause: Soilborne fungal disease; spreads in warm, acidic soils.

Prevention

  • Rotate crops: Avoid planting any brassica in the same spot for 3+ years.
  • Improve soil pH: Keep pH around 6.8–7.2.
  • Ensure good drainage to avoid saturated soil.

My experience: Raised beds and regular pH checks have prevented clubroot entirely.

2. Downy Mildew

Symptoms: Yellow patches on upper leaves, gray fuzz on undersides.
When it thrives: Cool, damp nights + poor airflow.

Prevention and Controls

  • Give rutabaga good spacing (10–12 inches).
  • Water early in the day, not evenings.
  • Use light pruning of overcrowded leaves to boost airflow.

My experience: Once I stopped overhead watering in late afternoon, mildew nearly vanished.

3. Powdery Mildew (Occasional in Mild Winters)

Symptoms: White powdery film on leaves.
Season: Dry, mild fall periods.

Natural Control

  • Spray 1 tablespoon baking soda + a drop of dish soap in 1 quart water.
  • Improve airflow.
  • Remove heavily affected leaves.

4. Black Rot (Rare but Serious)

Symptoms: V-shaped yellow lesions, darkened veins.
Cause: Bacterial infection spread by splash and contaminated tools.

Prevention

  • Avoid overhead watering when possible.
  • Rotate crops.
  • Buy clean seed from reputable suppliers.

🧰 My Natural Pest-Prevention Routine (What Works Every Year)

From sowing:

  • Cover rutabaga with floating row cover.
  • Plant garlic or scallions along the edges.

After seedlings are established:

  • Remove row cover once the weather is cold enough to discourage pests.
  • Add shredded leaf mulch to keep soil moist and suppress weeds.
  • Interplant calendula for aphid control.

Weekly:

  • Inspect leaves for frass (caterpillars).
  • Check young leaves for flea beetles.
  • Water early in the morning only.

Monthly (fall/winter):

  • Refresh mulch.
  • Remove any diseased leaves promptly.

My experience: Preventing issues before they begin—especially with row cover and interplanting—has done far more than any treatment after the fact.

Rutabaga Learning Hub

Start here: How to Plant, Grow, and Harvest Rutabaga: A Complete Guide

Planting, Timing & Setup

Care, Water & Feeding

Companions & Intercropping

Pests, Diseases & Troubleshooting

Harvest, Storage & Kitchen

Varieties & Background

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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