Sweet Olive with Anthracnose? Rare but Treatable

Osmanthus fragrans

Susceptibility: Low Severity: High Difficulty: Easy

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: Sweet Olive

💧 How to Water

Water every 7-12 days during the growing season, providing about 1 inch of water per week. Once established, the plant is somewhat drought-tolerant. Avoid waterlogging as it leads to root rot. Ensure good drainage at all times.

☀️ Lighting

Prefers full sun to partial shade, with at least 6 hours of direct sunlight daily. More sunlight encourages abundant flowering. In hot climates, provide afternoon shade to prevent leaf scorch. Avoid deep shade, which reduces blooming significantly.

🪴 Ideal Soil

Plant in fertile, well-draining soil. Tolerates a range of soil types including clay and sandy soils, but cannot survive in waterlogged conditions. Amend heavy clay with organic matter for better drainage.

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