Black Tip of Mango:
Causal Organism:
The black tip of mango is not caused by a biological pathogen like a fungus, bacterium, or virus. Instead, it is a physiological disorder. The primary cause is attributed to atmospheric pollutants such as sulfur dioxide (SO₂), which are often released from brick kilns located near mango orchards. The disorder is particularly prevalent in regions where brick kilns operate in close proximity to mango plantations.
Symptoms:
- Initial Symptoms: The tips of the mango fruit start showing a brown to black discoloration.
- Progression: The affected area expands towards the base of the fruit, covering a significant portion of the fruit’s surface.
- Fruit Deformity: In severe cases, the fruit may become deformed and exhibit retarded growth.
- Necrosis: Tissue necrosis (death of tissue) occurs at the affected parts, leading to blackening and hardening of the tip.
- Reduced Market Value: Fruits with black tips are often downgraded in quality and market value.
Disease Cycle:
Since black tip is a physiological disorder and not a disease caused by a living pathogen, it doesn't have a traditional disease cycle involving infection, sporulation, and spread. However, the occurrence and severity can be described in terms of environmental conditions and human activities:
1. Emission of Pollutants: Sulfur dioxide (SO₂) emissions from nearby brick kilns are the primary source of the problem.
2. Deposition on Fruits: The emitted SO₂ settles on the developing mango fruits, particularly affecting those at the tip.
3. Physiological Response: The interaction of SO₂ with the plant tissue causes oxidative stress and leads to cellular damage, resulting in blackening of the fruit tips.
Management:
Managing black tip of mango involves both preventive measures and cultural practices aimed at reducing the exposure of mango orchards to pollutants:
1. Relocation of Brick Kilns: One of the most effective measures is the relocation of brick kilns away from mango orchards. This reduces the exposure of mango trees to harmful pollutants.
2. Buffer Zones: Establishing green belts or buffer zones around mango orchards can help in absorbing pollutants before they reach the fruit.
3. Orchard Management:
- Regular Monitoring: Keeping a close watch on the orchard for early signs of black tip and taking prompt action.
- Irrigation: Adequate and timely irrigation can help in washing away pollutants from the fruit surface.
- Nutrient Management: Ensuring proper nutrient supply to the trees can enhance their resilience to environmental stress.
4. Use of Protective Sprays: In some cases, protective sprays like lime or milk of lime (calcium hydroxide) can be applied to the fruit surface to neutralize the acidic pollutants.
5. Awareness and Advocacy: Educating farmers and local communities about the causes and preventive measures for black tip can lead to better management practices and policy advocacy for pollution control.