Yellow leaf disease
Causal agent:Phytoplasma-like organisms (PLO's). Symptoms
- Symptoms include yellowing of leaves and shedding of both mature and immature nuts. Endosperms of diseased nuts are soft, blackish and not suitable for consumption.
- Yellowing at the tips of leaf lets in 2or3 leaves of the outermost whorl is the first visible symptom.
- Brown, necrotic streaks run parallel to lamina in unfolded leaves, with the development of leaves, yellowing starts form the tips of leaflets, gradually extending to the middle of the lamina.
- One or two leaflets in any of the crown or the entire foliage may be affected by the disease. Tips of the chlorotic leaves eventually dry up.
- In advanced stages, leaves are reduced in size, become stiff and pointed, closely bunched and puckered. Finally the crown falls down leaving the base trunk.
- Root tips turn dark and gradually rot. Production of lateral root is reduced.
- Affected fruits fall down. Some of the palms exhibiting foliar yellowing may produce normal nuts and all nuts in the bunch may not show kernel discoloration.
- Blocking of xylem vessels of older leaves of diseased palms, degeneration of cortex and presence of tyloses in xylem are also noticed in diseased roots.
![Arecanut yellows Arecanut yellows](/moodle/file.php/96/Areca_yellows.jpg) Management
- True Mangala seedlings and South Canara variety showed tolerance to this disease. The hybrid SaigonĂ—mangala yielded max number of nuts with minimum disease intensity.
- Palms which received higher dose of potassium and magnesium recorded minimum disease intensity.
- Use of Chlorotetracyclin hydrochloride (Aureomycin) and tetracycline chloride (achromycin) through root feeding and stem injection had no ameliorative effect on the disease.
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Last modified: Monday, 6 February 2012, 6:55 AM