Delta Maidenhair Fern with Anthracnose? Rare but Treatable

Adiantum raddianum

Susceptibility: Low Severity: High Difficulty: Hard

Anthracnose is a fungal disease caused by fungi in the genus Colletotrichum that affects many plants, including vegetables, fruits, and trees. The disease thrives in cool, wet conditions, causing dark, sunken lesions on leaves, stems, flowers, and fruits.

🔍 Symptoms

• Small irregular yellow or brown spots on leaves
• Dark sunken lesions on leaves, stems, flowers and fruits
• Water-soaked lesions that darken as they age
• Pink gelatinous masses of spores in lesion centers during warm, moist weather
• Spots that expand and may cover entire leaves
• Defoliation in advanced stages

❓ Possible Causes

→ Caused by fungi in the genus Colletotrichum
→ Cool wet weather promotes development
→ Optimum temperature between 75-85°F (24-29°C)
→ Foliage wet for extended periods of time
→ Fungi overwinter in seeds, soil and garden debris
→ Spores spread through water droplets

💊 Treatment

⚡

Quick Fixes

Remove and discard all visibly infected parts

Apply commercial systemic fungicide (azoxystrobin or mancozeb)

Adjust irrigation to avoid wetting foliage

Second application of systemic fungicide

Assess treatment effectiveness

🌿

Organic Treatment

Remove all infected plant parts and discard in plastic bag

Apply organic liquid copper spray to all plant surfaces

Switch irrigation regime to drip, avoiding foliage wetting

Second application of copper fungicide or neem oil

Assess progress and remove any new lesions

Final organic fungicide application and ongoing monitoring

🛡️ Prevention

✓ Implement drip irrigation instead of overhead watering
✓ Give plants enough room to breathe and reduce humidity
✓ Remove infected plant material after harvest
✓ Practice crop rotation between hosts and non-hosts
✓ Choose resistant plant varieties when possible
✓ Use western grown seeds not exposed to the disease
✓ Avoid wetting foliage during watering
✓ Ensure good air circulation around plants

🌱 Care Guide: Delta Maidenhair Fern

💧 How to Water

Keep the substrate always slightly moist but never waterlogged. Water frequently in small amounts, preferably with lime-free or rainwater. In summer it may need watering every 2-3 days.

☀️ Lighting

Needs bright indirect light. Never expose to direct sunlight which would burn its delicate fronds. Ideal near north or east-facing windows, or in bright bathrooms.

🪴 Ideal Soil

Light, well-draining substrate. Mix universal potting mix with perlite in equal parts. Prefers slightly acidic soil (pH 5.5-6.5). Adding peat helps retain moisture.

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