Controlling Anthracnose on Commercial Papaya Farms

Integrated Management of Colletotrichum gloeosporioides in Papaya

Anthracnose, caused by Colletotrichum gloeosporioides, is a devastating post-harvest disease of papaya (Carica papaya), causing sunken, water-soaked lesions that render fruit unmarketable. For a farm scaling to trailer-loads per week, a robust, multi-tactic program is essential.

Pre-Harvest Cultural Practices

• Sanitation: Remove and destroy all fallen fruit, infected leaves, and mummified fruit weekly. These are primary inoculum sources.
• Canopy management: Prune for airflow and light penetration. Avoid overhead irrigation; use drip or microsprinklers to keep foliage dry.
• Harvest timing: Pick fruit at early maturity (color break) to reduce field exposure.

Fungicide Program (Pre-Harvest)

• Protective sprays: Apply copper-based fungicides (e.g., Kocide 3000, copper hydroxide) or strobilurins (e.g., azoxystrobin/Abound) on a 14–21 day schedule during wet periods. Rotate FRAC groups to delay resistance.
• Bordeaux mixture (DIY): 4 lb copper sulfate + 4 lb hydrated lime per 50 gal water. Effective, low-cost, organic-approved. Apply every 2–3 weeks.

Post-Harvest Handling

• Sanitize packing lines: Wash bins, conveyors, and tools with 1:5 bleach solution (20% bleach). Rinse metal to prevent corrosion.
• Hot water dip: 48–50°C (118–122°F) for 20 minutes significantly reduces latent infections. Requires precise temperature control.
• Avoid wax coatings: Wax seals lenticels, creating anaerobic conditions that favor anthracnose development in storage.
• Cool rapidly: Hydrocool or forced-air cool to 10–13°C (50–55°F) immediately after packing.

Long-Term Strategies

• Source certified disease-free seedlings.
• Evaluate resistant/tolerant cultivars for future plantings.
• Consider biological controls (e.g., Bacillus subtilis QST 713) as part of rotation.

Consistent sanitation, timely fungicide rotation, and meticulous post-harvest handling are the pillars of anthracnose management at scale.