Mahali disease, often referred to as Koleroga or fruit rot, is a destructive disease primarily affecting the nuts of arecanut and coconut palms, leading to their premature decay and eventual shedding. Understanding its symptoms is crucial for early detection and effective management.
Understanding Mahali Disease Symptoms
The disease manifests through distinct stages, beginning with subtle lesions and progressing to widespread rot and significant crop loss. It is particularly prevalent during periods of heavy rainfall and high humidity.
Early Indicators
The initial signs of Mahali disease are often the most important for early intervention:
- Water-Soaked Lesions: The first visible symptoms appear as dark green or yellowish water-soaked lesions on the surface of the nuts. These spots are typically moist to the touch and indicate the beginning of the infection.
- Location: These lesions are most commonly observed near the perianth (also known as the calyx), which is the part of the flower that encloses the reproductive organs and later forms the base of the nut.
Advanced Stages and Characteristic Damage
As the disease progresses, the symptoms become more severe and easily identifiable:
- Rapid Rotting: The initial lesions quickly expand, leading to the rapid rotting of the entire nut. The affected nuts become soft, discolored, and lose their structural integrity.
- Extensive Shedding: A hallmark characteristic of Mahali disease is the extensive and premature shedding of these immature, rotting nuts. They detach from the bunch and can be found scattered on the ground near the base of the palm tree. This shedding represents a significant loss of potential yield.
- Fungal Growth: In advanced stages, a white, cottony fungal growth may be visible on the surface of the infected nuts, especially under humid conditions.
Summary of Symptoms
The progression of Mahali disease can be summarized as follows:
| Symptom Stage | Description | Key Observation |
|---|---|---|
| Initial Phase | Dark green/yellowish, water-soaked lesions appear on the nut surface. | Spots concentrated near the perianth (calyx) of the nut. |
| Progression | Lesions rapidly expand, causing the entire nut to rot, becoming soft and discolored. | Discoloration and softening of the nut, leading to decay. |
| Characteristic Impact | Extensive shedding of immature, rotting nuts from the tree. | Rotting nuts scattered widely on the ground around the palm. |
Impact on Crop Yield
Mahali disease primarily targets young and developing nuts, directly impacting the harvest. The widespread shedding of immature fruits due to rot can lead to substantial reductions in crop yield, making it a significant concern for cultivators of arecanut and coconut.
For further information on management strategies, you can refer to agricultural resources like the Indian Council of Agricultural Research (ICAR) or local agricultural university extension services.
