Lady Slipper Orchid with Anthracnose: Prevention & Cure

Paphiopedilum insigne

Susceptibility: Moderate Severity: High Difficulty: Medium

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: Lady Slipper Orchid

💧 How to Water

Water thoroughly when the top inch of the potting medium feels dry, typically once a week. Use tepid water and avoid wetting the crown, as standing water in the leaf axils can cause bacterial rot. Reduce watering slightly in winter.

☀️ Lighting

Provide bright, indirect light (800-1000 foot-candles). East or west-facing windows are ideal. Avoid direct sunlight, which can burn the leaves. The plain green leaves indicate this is a cool-growing type that tolerates lower light than mottled-leaf varieties.

🪴 Ideal Soil

Use a well-draining orchid mix of fine-grade fir bark, perlite, and sphagnum moss. The medium should retain some moisture while allowing air to reach the roots. Repot every 2 years or when the medium starts to decompose.

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