Diseases of Fruit Plantation Medicinal and Aromatic Crops

Leaf scorch decline

Leaf scorch decline is a disorder of coconut palms, first detected in Sri Lanka as early as 1955. The volume of inflorescence sap collected from LSD-affected palms was much reduced as compared to healthy palms, but the composition of the sap remained unaltered.
Soil Condition:
Rapid tappering associated with Leaf Scorch Decline occurs under adverse soil and environmental conditions. The growth is adversely affected, root system severely damaged, tapped continuously and succumb. In laterite and gravelly soils, impeded drainage through hard pan beneath, may be an adverse soil physical factor in Leaf Scorch Decline. A relatively high rate of tappering has been noticed in shallow and compact soils that have not been fertilized regularly.
Symptoms

Necrosis of lower whorl of fronds of grown up palms and downwards curling of leaflets are the main characteristics,of Leaf Scorch Decline. After a short period, crown is reduced in size and the trunk begins to tap and as result the formation of inflorescence may cease completely. Extensive damage of root system and root decay are found to be common in infected palms. This malady is often associated with cracking of heavy clay soil and visible magnesium deficiency symptoms on leaves.

Management

• Structural improvement of laterite/gravelly soil with addition of organics may improve the condition of affected palms.
• Round bench terracing at a height of 0.5 m with coconut husks, 1 m away from the base of the palm and filling the space with porous soil, helps to induce new root formation.
• Balanced soil manuring, including application of magnesium sulphate @ 1 kg/palm/year will be beneficial).