- Initial visible symptoms of the disease are the yellowing of spindle leaf.
- As the disease advances, the spindle loses its green colour and turns yellow and later changes to brown and droop down.
- The disease also spreads to younger leaves around the spindle.
- The tender leaf tissues and leaf sheath show water soaked lesions that later turn brown in colour.
- In advanced stages of disease, the spindle can be drawn out of the crown with a slight pull.
- Water soaked lesions can be traced to the underlying primordial tissues of the petioles.
- The leaf sheath and tender leaf tissues below the spindle as well as the soft tissues of the bud become infected and destroyed.
- Withering of leaves progress further leaving a few fully expanded outer leaves on the crown.
- Even after the death of the central spindile nuts that are retained on the palm may grow to maturity.
- This disease proves fatal if not checked at early stages before the damage of the bud.
- When infection is severe, the entire crown degenerates into a slimy mass, emitting foul smell.
- After a few months the entire crown falls leaving only a barren stem.
Conduct regular survey of the garden especially during rainy season. Mark the trees showing yellowing of leaves surrounding the central spindle. Confirm the disease after inspecting the central spindle leaf.
Mere presence of the symptoms
Disease development coincides with the prevalence of high humidity and low temperature. The young palms are more susceptible to this disease. The fungus survives in the disease affected crown tissues during summer months and multiplies during the ensuing season. The fungus has a wide host range like palmyrah, arecanut, oil palm, rubber, citrus, cocoa, black pepper, cardamom, bougainvillea, hibiscus, jack, etc. Heavy rainfall,high relative humidity of 94-100% and temperature below 240C are highly favourable for disease spread.
- This disease can be effectively controlled if it is detected early.
- Strict phytosanitary measures are to be adopted for effective prevention of the disease.
- Palms killed due to bud rot along with decayed tissues should be removed and burnt.
- The infected tissues in the crown are to be removed and the wound dressed with 10% Bordeaux paste and covered with perforated polythene sheet till the next leaf emerges.
- Prophylactic spraying with 1% Bordeaux mixture should be carried out to all the trees around the infected palm.
- Apply salt and ash mixture or paddy husk after removing the affected portion in the crown and subsequently cover with mud pot.
- This will absorb moisture and keep the protected portion dry.
- Apply bleaching powder on the affected portion after removing the infected tissues.
- Drench the crown with 2 %Pseudomonas fluorescence or PGPR Mix 2 as a prophylactic measure before the onset of monsoon in endemic areas.
- Place perforated polythene sachets containing an aqueous paste of mancozeb (@2g/sashets) in the 2-5 top most leaf axils of palms with the onset of monsoon.
- Adopt control measures for Rhinoceros beetle which act as a predisposing factor for infection.