Common Collard Greens Pests and Diseases and Natural Controls

Collard greens are hardy and nutritious, but even experienced gardeners like myself—after 30+ years growing collards—know that pests and diseases can quickly reduce yields and damage leaves. Understanding the most common threats and how to control them naturally is essential for healthy, productive plants. In this guide, I’ll share practical, tried-and-true strategies that have worked consistently in my California gardens.

Table of Contents

Common Collard Pests

1. Aphids

Symptoms: Curling leaves, sticky residue (honeydew), presence of small green or black insects.
Natural Control: Spray with a strong stream of water, introduce beneficial insects like ladybugs, or use insecticidal soap.
Experience Tip: I’ve found early morning treatments are most effective, and repeated checks prevent infestations from spreading.

2. Cabbage Worms (Cabbage Loopers & Imported Cabbageworms)

Symptoms: Holes in leaves, frass (tiny green droppings), visible caterpillars.
Natural Control: Handpick caterpillars, use row covers to prevent egg-laying, or apply Bacillus thuringiensis (Bt) for severe infestations.
Experience Tip: Covering young plants immediately after transplanting has saved entire crops in my raised beds.

3. Flea Beetles

Symptoms: Tiny round holes, stunted seedlings, and reduced leaf quality.
Natural Control: Use row covers, sprinkle diatomaceous earth around plants, and maintain healthy soil with good organic matter.
Experience Tip: Flea beetles are worst in early spring; planting slightly later or using transplants can reduce damage.

4. Slugs and Snails

Symptoms: Irregular holes, slime trails, damage to low leaves.
Natural Control: Handpick at night, set beer traps, or scatter crushed eggshells or diatomaceous earth.
Experience Tip: In my container collards, slug damage is minimal when using elevated containers with barriers.

Common Collard Diseases

1. Black Rot

Symptoms: Yellow V-shaped lesions from leaf edges, black veins, plant stunting.
Natural Control: Practice crop rotation, remove infected leaves, and water at the soil level to keep leaves dry.

2. Downy Mildew

Symptoms: Yellow spots on upper leaves, gray fuzzy growth underneath.
Natural Control: Improve air circulation, avoid overhead watering, and space plants properly.

3. Clubroot

Symptoms: Swollen roots, wilting, stunted growth.
Natural Control: Raise soil pH to 6.5–7 using lime, rotate crops, and plant resistant varieties.

Preventive Care Tips

Use healthy seedlings free of pests.
Rotate crops yearly to reduce disease pressure.
Maintain consistent watering and mulching for plant vigor.
Monitor plants frequently—early detection is key to natural control.

My Experience

Even with decades of experience growing collards, pests and diseases are inevitable—but manageable. By observing plants carefully, using natural solutions, and maintaining strong plant health, you can enjoy abundant, tender leaves without relying on chemical pesticides. Healthy soil, proper spacing, and preventive care are the foundation of pest- and disease-free collard greens.

Collard Greens Pests & Diseases Quick Reference

Pest / Disease	Symptoms	Natural Control	Experience Tip
Aphids	Curling leaves, sticky honeydew, small green/black insects	Spray with water, introduce ladybugs, insecticidal soap	Morning treatments work best; check plants regularly to prevent spread
Cabbage Worms (Loopers & Imported Cabbageworms)	Holes in leaves, green droppings, visible caterpillars	Handpick, use row covers, Bacillus thuringiensis (Bt)	Cover young plants immediately after transplanting to prevent egg-laying
Flea Beetles	Tiny round holes, stunted seedlings	Row covers, diatomaceous earth, healthy soil	Plant slightly later or use transplants to reduce spring damage
Slugs & Snails	Irregular holes, slime trails	Handpick, beer traps, crushed eggshells	Elevated containers with barriers minimize damage
Black Rot	Yellow V-shaped lesions, black veins, stunted plants	Crop rotation, remove infected leaves, water at soil level	Early removal of infected leaves prevents spread
Downy Mildew	Yellow spots on upper leaves, gray fuzzy growth underneath	Improve airflow, avoid overhead watering, proper spacing	Adequate spacing prevents fungal buildup
Clubroot	Swollen roots, wilting, stunted growth	Raise soil pH (lime), rotate crops, resistant varieties	Plant in neutral/alkaline soil to reduce incidence

💡 Tip from My Experience:
Early detection and preventive care are the most effective strategies for natural pest and disease management in collards. Regular observation saves your harvest.