Understanding Papaya Anthracnose: A Widespread and Devastating Disease

Papaya anthracnose is a serious disease caused by the fungus Colletotrichum gloeosporioides. This fungal infection poses a significant threat to papaya production and the export of papaya fruits to international markets.

Impact on Papaya Production

Papaya anthracnose is a major constraint for papaya growers as it can severely damage the fruit, particularly during storage. This disease significantly hampers papaya production and limits the fruit’s export potential to larger overseas markets.

Disease Cycle

The Colletotrichum fungus survives the winter primarily in plant debris. To spread and infect new plants, the fungus produces spores that depend on water. These spores can be spread through wind, rain, or by farming equipment and workers when the papaya foliage is wet.

Once the fungus infects a papaya plant, it can penetrate the plant tissue directly without relying on natural openings such as stomata or wounds. Symptoms of the disease usually appear within 5-7 days after the infection has occurred. Warm, humid, and rainy weather conditions favor the development of the disease.

Signs & Symptoms

Papaya anthracnose can infect immature green fruits while still attached to the plant, but it remains dormant until the fruit starts to ripen. At this stage, symptoms of anthracnose, also known as chocolate spot, become visible.

Initially, small, well-defined pink spots appear on the ripening fruit’s surface. These spots later enlarge, becoming rounded, sunken, and turning brown to black in color. The lesions can be either water-soaked or dried and hard. In the center of the lesions, the fungus produces dark acervuli, often in a concentric pattern. Additionally, an orange to pink gelatinous mass of conidia (fungal spores) can be observed. The lesions can be easily separated from the flesh of the fruit, leaving a well-defined hole in the fruit.

In post-harvest infections, the lesions are usually superficial, slightly sunken, and irregular to rounded, displaying a characteristic reddish-brown color. As the fruit ripens further, the lesions may remain superficial or grow and become sunken. Occasionally, these symptoms, along with latex exudation, can be observed several days before harvest.

Infected leaves develop brownish to black spots, initially circular in shape, which later merge into more irregular necrotic areas. Severe infections can result in leaf loss. On the petioles (leaf stalks), elliptical lesions with dark acervuli in a concentric pattern may appear.

Disease Control

Chemical Control

To prevent and eradicate anthracnose disease in papaya, the following fungicides are recommended:

1. ABSOLUTE 325 SC: Mix 10g in 20 liters of water.
2. RANSOM 600WP: Mix 15g in 20 liters of water.
3. DUCASSE 250 EW: Mix 20ml in 20 liters of water.
4. DOMAIN 250 EC: Mix 10ml in 20 liters of water.
5. BRADLEY 500SC: Mix 10ml in 20 liters of water.
6. EXPLORER 3SL: Mix 10ml in 20 liters of water.
7. MEGAPRODE LOCK 525WP: Mix 30g in 20 liters of water.
8. JUPITER 125SC: Mix 15ml in 20 liters of water.
9. RIMETA GOLD 300SC: Mix 40ml in 20 liters of water.
10. PROVIDENCE 400WP: Mix 50g in 20 liters of water.
11. MILLIONAIRE 690WDG: Mix 40g in 20 liters of water.
12. GREENCOP 500WP: Mix 50g in 20 liters of water.

Non-Chemical Control Methods

In addition to chemical control, the following non-chemical methods can help manage papaya anthracnose:

1. Remove and destroy infected plants or plant parts, avoiding composting them.
2. Use papaya varieties that are resistant or tolerant to anthracnose.
3. Plant certified, disease-free, and healthy papaya planting materials.
4. Ensure well-drained soil for planting papaya trees.
5. Practice crop rotation with non-host plants.
6. Implement proper weed control measures.
7. Prevent post-harvest losses by avoiding fruit wounds, such as bruising, scratching, or puncturing.
8. Note that treating seeds with BIODISTINCTION XTRA can help control seed coat infections.
9. Enhance the effectiveness of fungicides by mixing them with INTEGRA (3ml/20l) as a sticker, spreader, wetter, and penetrant.
10. Alternate the use of different fungicides throughout the plant’s growing season to prevent the development of resistance.
11. Timely disease control is crucial to minimize losses caused by anthracnose infection.
12. Reapply fungicides after 1-2 weeks.
13. Provide proper nutrition to boost the plant’s immunity.

Conclusion

Papaya anthracnose, caused by the fungus Colletotrichum gloeosporioides, is a widespread and devastating disease that affects papaya production and its export potential. Understanding the disease cycle, recognizing the signs and symptoms, and implementing appropriate disease control measures, both chemical and non-chemical, are essential for managing this destructive disease and reducing its impact on papaya crops.

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