Major diseases of Arecanut are:-
1.Arecanut Foot rot or Anabe roga: Ganoderma lucidum
Symptom:
- The leaf lets in the outer holes of leaves become yellow and spread to the whole leaf and the leaves drooping down covering the stem.
- Later, the inner whole leaves also become yellow. Subsequently, all the leaves droop, dry up and fall off, leaving the stem alone.
- Then the stem also becomes brittle and easily broken by heavy wind.
- The base of the stem shows brown discoloration and oozing of dark fluid.
- Bracket shaped fructifications of the fungus called ‘anabe’ appear at the base of the trunk. Roots become discoloured, brittle and dried.
- When the infected trunk is cut brown discoloration can be seen up to one metre from ground level.
Management:
- Clean cultivation
- Destruction of infected trees and stumps
- Maintaining optimal plant population without over crowding.
- Providing good drainage facility and fertilizers and manures.
- Digging trenches to avoid root contact from diseased to healthy.
- Drench 1% Bordeaux mixture at frequent intervals.
2.Arecanut Yellow leaf disease: Phytoplasma
Symptom:
- Yellowing of tips of leaflets in 2 or 3 leaves of the outermost whorl.
- Brown necrotic streaks run parallel to veins in unfolded leaves.
- The yellowing extends to the middle of the lamina. Tips of the chlorotic leaves dry up. In advanced stage all the leaves become yellow.
- Finally, the crown leaves fall off leaving of a bare trunk. Root tips turn black and gradually rot.
Management:
- Maintain trees in seed vigour.
- Growing resistant varieties like true Mangala and south Kanara
- Application of potassium and magnesium more than the recommended level.
3.Arecanut Mahali / kolerogo/ fruit rot: Phytophthora arecae
Symptom:
- Rotting and excessive shedding of immature nuts from the trees.
- The water soaked spots initially develop at the base of the nut. Fruit stalks and rachis of the inflorescence are also affected.
- Nuts show large vacuoles and dark brown radial strands.
- Very often the top of the affected trees dries up resulting in the withering of leaves and bunches.
- Affected nuts fall off and show the white mycelial growth of the fungus.
Management:
- Clean cultivation
- Destruction of affected trees.
- Collection and burning of fallen nuts.
- Spray with Bordeaux mixture 1% before on the set of the monsoon and second spray 40-45.
4.Arecanut Bud rot: Phytophthora arecae
Symptom:
- The first symptom is the change of spindle leaf colour from green to yellow and then brown.
- The leaves rot and the growing bud rots causing the death of the palm.
- The affected young leaf whorl can be easily pulled off.
- The outer leaves also become yellow and drop off one by one leaving a bare stem.
Management:
- Destruction and removal of dead palms and bunches affected by mahali disease and drenching crowns with Bordeaux mixture 1% including surrounding healthy palms.
5. Inflorescence die back of Arecanut and button shedding: Colletotrichum gloeosporioides
Symptom:
- The disease appears on rachillae of the male flowers and then in the main rachis as brownish patches which soon spread from tip downwards covering the entire rachis causing wilting.
- The female flowers of the infected rachis shed and the whole inflorescence show ‘die back’ symptom.
- The fruiting bodies of the fungus, (conidia ) appear as concentric rings in the discoloured areas.
- The disease is severe mostly during dry condition. (February – March)
Management:
- Spraying with COC 0.25% or Mancozeb 0.2%
Source-
- TamilNadu Agritech Portal
