Coconut root wilt disease

Context: Coconut Root Wilt Disease is in the news due to its rapid spread across major coconut-growing regions of Kerala, Tamil Nadu and Karnataka, affecting lakhs of palms.

About Coconut root wilt disease:

What it is?

• A debilitating, non-fatal disease of coconut caused by a phytoplasma (phloem-limited pathogen), leading to chronic decline and major yield loss.
• Infected palms often remain alive but become long-term inoculum sources, enabling continued spread through vectors.

Origin and spread:

• First reported over 150 years ago from Erattupetta (Kerala) and has remained a persistent endemic problem.
• Spread is vector-borne, and is accelerated by continuous coconut belts, wind-assisted vector movement, and rising abiotic stress (temperature extremes) plus biotic stress (new sucking pests like whiteflies) that increase palm susceptibility.

Vector:

• Transmitted through sap-sucking insect vectors; commonly cited vectors in endemic areas include Stephanitis typica and Proutista moesta.

Key symptoms:

• Leaves look weak and droopy: The small leaf strips lose stiffness and hang down instead of standing firm — this is usually the first visible sign.
• Leaves turn yellow from the tips: Yellowing starts at the ends of leaves and slowly spreads inward; in later stages, parts of the leaves dry up and die.
• Leaves curl and cup inward: The leaf strips bend inward, making the whole leaf look ribbed or cup-shaped.
• Poor flowering and nut fall: The tree produces fewer flowers, nuts fall prematurely, and overall yield drops sharply.
• Tree slowly weakens: Roots start decaying, growth becomes poor, and in some cases the top of the trunk becomes thin and tapered.

Solutions and management:

• Select and multiply tolerant palms: Palms that continue to yield well despite disease pressure should be identified in farmers’ fields, scientifically confirmed, and multiplied through local nurseries.
• Good field and crop management: Remove badly affected, low-yielding palms to reduce disease spread. Improve soil health using green manure crops, ensure regular irrigation, proper drainage, and follow suitable intercropping to reduce stress on coconut palms.
• Strengthen palms with organic nutrition: Apply farmyard manure or green manure along with neem cake every year. Healthy soil and strong roots help palms tolerate disease better even if infection occurs.