Anthracnose is a disease caused by fungi that affects many fruit trees, such as apple, mango, avocado, citrus, and grape. It causes brown or black spots on leaves, flowers, and fruits, leading to defoliation, dieback, and fruit rot. Anthracnose can reduce the yield and quality of the fruit and, in severe cases, kill the trees. Therefore, using various methods, it is important to prevent and control anthracnose disease in fruit trees.
How to Prevent Anthracnose Disease in Fruit Trees
Anthracnose Disease Characters in Fruit Trees
Anthracnose is a disease caused by fungi from the Colletotrichum, Neofabraea, Sphaceloma, and Cryptosporiopsis genera. It affects fruit trees at different growth stages and presents various symptoms. Common symptoms include small, circular, or irregular dark or brown spots on leaves, stems, flowers, fruits, and other plant parts. Necrosis, resulting in holes, cracks, or recessed areas on the plant surface, may separate from healthy tissue, forming cankers or galls.
Leaves and shoots may wilt, yellow, curl, or distortion, and the tree may experience reduced growth, vigor, and productivity. The fungi can survive in infected debris or soil and spread through wind, water splashes, insects, animals, tools, or human activities. They can infect plants through natural openings or wounds, and warm and humid weather conditions are more conducive to the infection.
Selecting Resistant Varieties
To prevent anthracnose disease in fruit trees, choosing resistant or tolerant varieties is essential. Resistant varieties have genes that limit fungi infection, while tolerant varieties can recover without significant damage. These varieties can reduce the chemical fungicides and improve fruit yield and quality. Examples include Apple (Enterprise, GoldRush, Liberty), mango (Alphonso, Haden), avocado (Hass), citrus (Valencia orange), and grape (Concord).
Proper Planting and Care
Proper planting and care are essential to prevent anthracnose disease in fruit trees. This includes choosing healthy, disease-free materials from reputable sources, planting in well-drained soil with adequate organic matter, spacing the trees appropriately for good air circulation and sunlight penetration, watering regularly but avoiding overwatering or wetting the foliage, using drip irrigation or soaker hoses instead of sprinklers or overhead irrigation, fertilizing the trees according to their needs and soil test results, and mulching the soil around the trees with organic materials like straw. Following these tips, fruit trees can be more resilient.
Sanitation and Removal of Infected Materials
To prevent anthracnose disease in fruit trees, it is crucial to promptly remove and dispose of infected plant materials. This can reduce the amount of inoculum infecting new or re-infecting plants. To ensure sanitation, prune off branches or twigs with signs of cankers or lesions, cut at least 6 inches below the visible symptoms, and disinfect pruning tools.
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Discard fallen leaves, fruits, or flowers that show signs of decay; do not compost or use them as mulch. Remove and replace severely infected or dead trees, dig up the root system, and burn or bury the plant material. Clean and sanitize any tools, equipment, or containers in contact with infected plants.
Avoiding Overcrowding
- Avoid overcrowding by removing excess branches or shoots that cross or compete with each other. This will improve the tree’s shape and structure, allowing more light and air to reach the inner canopy.
- Following recommended guidelines, maintain a proper distance between trees based on their mature size and growth habit.
- Avoid planting other crops or plants near fruit trees that can compete for space, water, nutrients, or light. Choosing compatible plants that attract beneficial insects, repel pests, or fix nitrogen.
Protective Coatings and Sprays
To prevent anthracnose disease in fruit trees, protective coatings or sprays can be applied to the plant surfaces. These coatings can form a physical barrier, preventing fungi from infecting the plant tissue and inhibiting the growth or germination of spores. Examples include lime sulfur, copper, Kaolin clay, and baking soda.
Lime sulfur kills overwintering spores; copper interferes with enzyme activity and cell membrane function. Kaolin clay creates a film that prevents spore adhesion, and baking soda raises the pH of the plant surface, making it less favorable for fungal growth. These co