Rhizome rot / soft rot (ginger & turmeric)
A warm-season, waterlogged soft rot of the rhizome and stem base — pseudostems yellow and collapse and the rotted rhizome smells foul.
- Pathogen
- Fungus (Pythium) + Fusarium/bacteria
- Spreads by
- Infected seed rhizomes; soil & water
- Favoured by
- Warm, wet, waterlogged soil
- Main risk
- Rhizomes rot; clumps collapse in patches
Overview
Rhizome rot (soft rot) is the most serious and destructive disease of ginger, and an important one of turmeric. It is mainly caused by the soil- and water-borne fungus Pythium, often joined by Fusarium and soft-rot bacteria. The first sign above ground is a pale, water-soaked yellowing of the lower leaves and pseudostem, which spreads up so the pseudostem becomes soft and watery at the base, and the shoot topples and collapses.
Below ground the rhizome turns into a soft, watery, foul-smelling rot; the outer tissue sloughs off leaving only the fibres. It spreads fast in patches during warm, wet, waterlogged conditions and is carried on infected seed rhizomes and in the soil and irrigation water. Because it is driven by waterlogging and infected seed, management is built on good drainage, disease-free seed rhizomes, seed treatment and raised beds rather than any rescue after the rot sets in.
How to identify it
- Pale, water-soaked yellowing of the lower leaves and pseudostem, spreading upward.
- A soft, watery rot at the base of the pseudostem, so the shoot topples and collapses.
- A soft, watery, foul-smelling rot of the underground rhizome, the outer tissue sloughing off to leave fibres.
- Clumps dying and spreading in patches, worst in warm, wet, waterlogged parts of the field.
What causes it and when
- Mainly the soil- and water-borne fungus Pythium, often with Fusarium and soft-rot bacteria.
- Favoured by warm, wet, waterlogged soil and high rainfall — a monsoon and low-lying-field disease.
- Carried on infected seed rhizomes and in soil and irrigation water; spreads fast once established.
- Made worse by poor drainage, low-lying land and continuous ginger/turmeric on the same land.
Cultural & organic control
- Plant only healthy, disease-free seed rhizomes from a clean crop; discard any soft or discoloured setts.
- Grow on raised beds with excellent drainage — never in low-lying, waterlogged land.
- Rotate away from ginger/turmeric, and rogue out and remove affected clumps with the soil around them.
- Treat seed rhizomes and soil with a bio-agent (e.g. Trichoderma) where recommended.
Chemical control
- Treat seed rhizomes before planting with a recommended fungicide dip (e.g. mancozeb or metalaxyl+mancozeb).
- At the first appearance in the field, drench the affected patch and surroundings with a CIB&RC-registered fungicide and stop the water.
- Improve drainage immediately — chemicals do little while the soil stays waterlogged.
- Confirm the current seed-treatment and drench product for your crop with your local KVK.
Prevent it coming back
- Base the crop on disease-free seed rhizomes, raised beds and excellent drainage.
- Rotate with non-hosts, treat seed and soil, and establish Trichoderma in the bed.
- Rogue and remove affected clumps early, and never save seed from a rot-affected crop.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
My ginger/turmeric shoots are yellowing and collapsing and the rhizome is soft and smelly. What is it?
That water-soaked yellowing, a soft watery base to the pseudostem, and a foul-smelling soft rot of the rhizome is rhizome rot (soft rot) — the most serious disease of ginger, mainly caused by Pythium. It races through warm, waterlogged soil. Stop the water and improve drainage at once, rogue out affected clumps, and next season plant disease-free seed rhizomes on raised, well-drained beds after a fungicide dip.
Why is drainage so important for rhizome rot?
Because the fungus that causes it (Pythium) is water-borne and thrives in warm, waterlogged soil — the rot spreads fastest exactly where water stands. Growing on raised beds with excellent drainage, and avoiding low-lying land, denies the fungus the standing water it needs. That is why drainage, rather than any spray, is the backbone of control; a drench does little while the soil stays saturated.
Can I use seed rhizomes from an affected crop if they look fine?
No — it is one of the main ways the disease carries over. Rhizomes from an affected crop can carry the fungus even if they look sound, and planting them re-sows the rot. Always take seed rhizomes from a healthy, disease-free crop, discard any soft or discoloured setts, and treat the seed with a recommended fungicide dip before planting on raised, well-drained beds. Confirm the treatment with your KVK.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.