Crab Eye Spot Disease on Durian Plants | Recognize - How to Prevent

Crab Eye Spot Disease on Durian Tree

Crab spot disease is a significant challenge for many durian farmers. Protecting durian trees and maintaining product quality requires identifying the disease and applying effective preventive and treatment measures. In this article, Sataka provides a detailed guide on recognizing and managing crab spot disease to protect your durian orchard.

1. What is Crab Spot Disease in Durian?

This disease causes severe damage during the flowering and fruiting stages, resulting in poor fruit set, misshapen fruits, and premature fruit drop. Crab spot disease is often mistaken for rust disease caused by fungi. However, careful observation reveals that crab spot disease produces circular lesions with concentric rings in gray, reddish-brown, and a yellow outer edge.

Characteristics of crab eye spot disease on durian trees

2. Causes of Crab Spot Disease in Durian

Crab spot disease is caused by the fungus Colletotrichum zibethinum, which aggressively attacks and weakens trees, resulting in significant damage to leaves, fruits, and other parts. This fungus not only reduces yield but also severely impacts the commercial quality of durian.

2.1 Favorable Conditions for Fungal Growth

The fungus Colletotrichum zibethinum thrives in warm, humid conditions, with temperatures between 20–30°C and high humidity providing an ideal environment for its growth and spread. Without control measures, the disease can quickly proliferate under such conditions, causing extensive damage to durian trees.

2.2 Modes of Disease Transmission

Crab spot disease spreads through three main pathways:

• Wind and Rain: These natural factors play a significant role in dispersing fungal spores. During strong winds or heavy rain, spores can spread from infected to healthy trees, causing rapid disease transmission within the orchard.
• Insects: Certain insects, such as leaf miners, act as intermediaries, carrying fungal spores from infected to healthy trees. When these insects attack young leaves, they create small wounds that allow the fungus to invade and cause damage.
• Garden Tools: Using unclean garden tools between trees can also spread the disease. Fungal spores can cling to tools and be transferred to other trees during use.

Leaf miners, while not directly causing crab spot disease, are significant indirect contributors. Their attacks on young leaves create entry points for the fungus, emphasizing the need for insect control as part of disease management.

Causes of crab eye spot disease on durian trees

3. Common Symptoms of Crab Spot Disease in Durian

3.1 On Leaves

The disease manifests as small, bright yellow spots on young leaves, resembling pinpricks. These spots quickly turn light brown and appear on both leaf surfaces. The spots are surrounded by bright yellow halos, contrasting with the brown lesions. While the disease does not deform leaves, it reduces the tree’s resistance, affecting photosynthesis and growth.

Symptoms of crab eye spot disease on durian trees

3.2 On Fruits

Crab spot disease affects durian fruits by forming brown lesions, often rough with raised edges. In the center of the lesions, the fruit tissue may die and crack. Severe infections cause fruits to deform, lose moisture rapidly, dry out, and drop prematurely, reducing the commercial value of the durian.

4. Damage Caused by Crab Spot Disease in Durian

If left uncontrolled, crab spot disease can cause significant harm. The fungus Colletotrichum zibethinum affects not only leaves but also branches and fruits. Severe infections lead to stunted tree growth and reduced yields. Infected fruits lose their market value, directly impacting farmers’ profits.

Damage of crab eye spot disease on durian trees

5. Prevention and Treatment of Crab Spot Disease in Durian

5.1 Prevention

• Provide Adequate Nutrition: Strengthen the tree’s resistance by supplying sufficient nutrients. Use macro and micronutrient fertilizers, and foliar-feed micronutrients during critical stages, especially when fruits are developing. This keeps trees healthy and reduces disease susceptibility.
• Manage Planting Environment: Maintain a clean and well-ventilated orchard. Remove and destroy infected leaves and fruits to prevent fungal spread. This also helps reduce humidity, which fosters fungal growth.

5.2 Treatment

• Use Fungicides: When the disease appears, fungicide application is necessary. Effective fungicides for crab spot disease include:

  • Metalaxyl: For prevention and control of Phytophthora fungi.
  • Mancozeb: To control fungal pathogens.
  • Copper Oxychloride: To inhibit the spread of crab spot disease.
  • Fosetyl-Aluminium: Often combined with other active ingredients for effective control of crab spot disease.

• Application Instructions:
  Mix 25–50ml of fungicide with 200 liters of water and spray evenly on infected areas. Repeat the spraying 2–3 times, with 3–5 days between applications, for optimal results. This regimen kills fungal pathogens, supports tree recovery, and boosts resistance to other diseases.

How to prevent crab eye spot disease on durian trees

Managing crab spot disease in durian requires attention and proper measures to protect tree health. Preventive and treatment strategies, including adequate nutrition, environmental management, and fungicide application, play a vital role in controlling the disease.

Sataka provides high-quality and effective fungicides to support farmers in managing crab spot disease. Contact us for advice and solutions to safeguard your durian orchard. We are here to help!