Radish with White Mold: Prevention & Cure

Raphanus sativus

Susceptibility: Moderate Severity: High Difficulty: Easy

White mold (Sclerotinia sclerotiorum) is a devastating fungal disease affecting over 400 plant species worldwide. The fungus produces black, seed-like structures (sclerotia) that can survive in soil for 5 or more years. The disease is favored by cool, moist weather (50-68°F/10-20°C), especially during flowering.

🔍 Symptoms

• Sudden wilting and yellowing of leaves
• Fluffy white mold growth on stems and leaves
• Water-soaked lesions expanding irregularly
• Soft, watery rot near soil level
• Black sclerotia (0.5-1cm) in white fungal mass
• Grayish-green appearance before wilting
• Infected stem sections become brittle and tan-colored

❓ Possible Causes

→ Fungus Sclerotinia sclerotiorum surviving in soil via sclerotia
→ Prolonged cool, moist conditions (50-68°F/10-20°C)
→ High humidity during flowering period
→ Poor air circulation from dense planting
→ Wind-borne spores from germinated sclerotia
→ Direct contact with contaminated soil
→ Fungus survival on plant debris for 5+ years

💊 Treatment

⚡

Quick Fixes

Immediate removal

Remove and completely destroy all infected plants. Burn or bag and dispose in trash.

Apply fungicide

Apply systemic fungicide (SDHI or DMI) to neighboring healthy plants preventively.

Reduce moisture

Stop all overhead watering. Use drip only. Improve ventilation/drainage.

Isolate area

Create buffer zone by removing plants within 20-inch radius of infection.

Intensive monitoring

Inspect remaining plants 2x daily for 14 days.

🌿

Organic Treatment

Remove infected plants

Carefully remove entire plant without spreading sclerotia. Burn or bury deeply (24+ inches). Do not compost.

Apply biocontrol

Apply Coniothyrium minitans to soil per instructions. This fungus parasitizes Sclerotinia sclerotia.

Improve circulation

Thin adjacent plants to improve airflow. Space plants 12-18 inches apart.

Adjust irrigation

Switch to drip irrigation. Water early morning. Avoid wetting foliage.

Soil solarization

If possible, cover soil with clear plastic for 4-6 weeks in summer (kills sclerotia).

Monitoring

Inspect plants daily for 3 weeks. Remove any new infection immediately.

🛡️ Prevention

✓ Plant with proper spacing to promote air circulation
✓ Avoid excessive irrigation during and after flowering
✓ Use drip irrigation instead of overhead sprinklers
✓ Remove and destroy infected plants immediately
✓ Implement crop rotation with 2-3 years of non-host crops (cereals, corn)
✓ Water early in day so foliage dries before nightfall
✓ Clean up all crop debris after harvest
✓ Avoid planting susceptible species in areas with disease history

🌱 Care Guide: Radish

💧 How to Water

Water radishes every 2–3 days to maintain consistent soil moisture. Uneven watering can cause the roots to crack or become pithy and bitter. Avoid waterlogged soil, which promotes root rot. In hot weather, check soil moisture daily.

☀️ Lighting

Radishes thrive in full sun with at least 6 hours of direct sunlight per day. Partial shade is tolerated, but results in slower growth and less flavorful roots. Ensure good light exposure for compact, well-developed roots.

🪴 Ideal Soil

Use a light, loose loamy or sandy soil with good drainage and a pH of 6.5–7.0. Avoid heavy clay soils that impede root development. Enrich soil with compost before planting. Loose soil produces smoother, more tender roots.

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