The Mango Dieback Disease caused by the fungus Lasiodiplodia theobromae is a serious threat to mango crops worldwide. The fungus primarily infects stressed or wounded trees, such as those subjected to drought, insect damage, or pruning wounds. The pathogen enters the plant through the wounds and spreads rapidly throughout the plant, causing extensive damage to the vascular tissues. Mango Dieback Disease affects the quality and yield of mango crops and causes economic losses to farmers and the mango industry.
Effective management strategies are essential to control the spread of the disease and prevent its devastating effects on mango crops. To effectively manage this disease, it is important to understand its disease cycle, the mode of disease spread, and the best methods for controlling it. This article will provide an overview and discussion of the Mango Dieback Disease in Mango crops, including its symptoms, identification techniques, and control.
Mango Dieback Disease Management
The Causal Organism of Mango Dieback Disease
- Lasiodiplodia theobromae is a facultative saprophytic fungus that belongs to the Family Botryosphaeriaceae of Order Botryosphaeriales of the Phylum Ascomycota.
- The fungus is characterized by small, dark, flask-shaped fruiting bodies called pycnidia, which produce and release spores that can infect new plant tissues.
- The pathogen primarily infects stressed or wounded mango trees.
- It commonly survives in soil, plant debris, and infected plant tissues.
The Disease Cycle of Mango Dieback Disease
The disease cycle of the Mango Dieback Disease, Lasiodiplodia theobromae, in Mango Crops begins when the pathogen enters the plant through natural openings, such as stomata and lenticels, or wounds caused by pruning, insect feeding, or other mechanical injuries. Once inside the plant, the fungus colonizes the vascular tissues and causes extensive damage, leading to wilting, dieback, and, eventually, the death of the tree.
It produces a range of enzymes and toxins that facilitate its penetration and colonization of plants’ vascular tissues. As the disease progresses, symptoms such as wilting, leaf yellowing, and blackening branches and leaves become significant. It can also trigger the plant’s defense mechanisms, leading to further stress and damage. The fungus produces pycnidia in the infected tissues, which release spores that can infect new plant tissues or be dispersed to other plants by wind, rain, and insects.
The spores can infect nearby healthy tissues, causing secondary infections and further disease spread. The cycle repeats, and the fungus can survive in the infected plant tissues, soil, or plant debris, which is the source of primary inoculums until conditions are favorable for infection and disease development again. The disease is most prevalent in October and November.
Occurrence of Mango Dieback Disease in Mango Crop
- Location of Mango Dieback disease: This disease occurs in mango crops in India, South Africa, Bangladesh, Sri Lanka, Thailand, the Philippines, the United States, Mexico, Brazil, and Australia.
- Host range: The most common crops affected by Lasiodiplodia theobromae are mango, avocado, grapevine, citrus, papaya, tomato, eggplant, and ornamental plants.
Favorable Conditions for Mango Dieback Disease Spread in the Field
- Warm and humid conditions, with temperatures between 27-32°C and 50-90% relative humidity, and heavy rainfalls are ideal for spore germination and infection.
- The disease thrives in poorly drained soils or areas with standing water.
- Pruning injuries, insect damage, wounds, and other mechanical injuries are conducive to the disease’s spread.
- The nutrient deficiencies such as calcium, magnesium, and potassium weaken the plant’s defense mechanism making them more susceptible to Mango Dieback Disease.
- Overcrowded plants are also more susceptible to injuries, making them more vulnerable to fungal infection.
- Poor sanitation practices, such as inefficient removal of dead plant material or not removing fallen fruit, can create a favorable environment for the spread of the