Golden Shower Orchid with Anthracnose: Prevention & Cure

Oncidium varicosum

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: Golden Shower Orchid

💧 How to Water

Water when the substrate feels dry to the touch, usually 2-3 times per week in summer and once weekly in winter. Preferably water in the late afternoon. Ensure water drains completely, avoiding accumulation.

☀️ Lighting

Appreciates bright indirect light, preferably a few hours of morning sun. Avoid direct sun during the hottest hours. Dark green, soft leaves indicate insufficient light.

🪴 Ideal Soil

Use substrate specific for epiphytes: 40% sphagnum moss, 30% charcoal, and 30% ground pine bark. The substrate must be very well-draining to prevent root rot.

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