Ratoon stunting (sugarcane)
A hidden bacterial disease that stunts and thins the cane with almost no outward symptoms — seen only as steadily falling ratoon yields.
- Pathogen
- Bacterium (Leifsonia xyli)
- Spreads by
- Cutting knife/harvester sap; infected setts
- Favoured by
- Infected seed; ratooning; shared tools
- Main risk
- Hidden stunting; steadily declining yields
Overview
Ratoon stunting disease (RSD) is one of the most economically important yet most easily missed diseases of sugarcane, caused by the bacterium Leifsonia xyli subsp. xyli, which lives in the water-conducting tissue. Its hallmark is the absence of clear external symptoms: affected stools are simply stunted, with thinner, shorter canes and reduced tillering and vigour, so the crop looks generally poor rather than diseased — and the loss builds up as ratoon after ratoon yields less.
The one internal clue is tiny orange-to-reddish dots or short commas in the nodal tissue when a cane is cut, but confirmation really needs a lab test. It is spread mechanically — mainly by the cutting knife/harvester moving sap from plant to plant, and by planting infected setts; it is not spread by insects or soil. Because it is seed- and knife-borne and hidden, control rests entirely on hot-water-treated, disease-free seed, disinfecting cutting tools, and not endlessly ratooning an infected crop.
How to identify it
- General stunting — thinner, shorter canes, reduced tillering and vigour — with almost no clear external symptom.
- A crop that just looks poor and yields less, especially in successive ratoons, rather than obviously diseased.
- Tiny orange-to-reddish dots or short commas in the nodal tissue when a cane is cut across (a hint, not proof).
- Reliable confirmation needs a laboratory test — it is easy to mistake for poor management.
What causes it and when
- The bacterium Leifsonia xyli subsp. xyli, living in the vascular tissue of the cane.
- Spread mechanically — mainly by the cutting knife or harvester carrying infected sap from plant to plant, and by planting infected setts.
- Not spread by insects or soil, so tool and seed hygiene are what matter.
- Builds up through successive ratoons of an infected crop, causing a steady yield decline.
Cultural & organic control
- Plant only healthy, disease-free seed cane from a certified/clean seed nursery.
- Do not keep ratooning a suspected infected crop indefinitely — restart from clean, treated seed.
- Maintain a three-tier healthy seed programme so clean seed is available.
- Rogue obviously poor, stunted stools and keep records of seed sources.
Seed & tool treatment
- Treat seed setts by hot water treatment (HWT) at the recommended temperature and time to free them of the bacterium — the key control.
- Disinfect the cutting knife/harvester blades regularly between stools/fields so they do not carry sap-borne infection.
- There is no curative spray — control is entirely seed- and hygiene-based.
- Confirm the current HWT schedule and seed programme for your area with your local KVK/cane research station.
Prevent it coming back
- Base every planting on hot-water-treated, disease-free seed from a clean seed nursery.
- Disinfect cutting tools routinely and limit the number of ratoons from any seed source.
- Maintain the healthy seed programme so RSD does not silently erode yields over the years.
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 sugarcane yields keep falling in successive ratoons with no obvious disease. Why?
A steady, hidden decline in ratoon yields with thin, stunted canes and no clear external symptom is the classic sign of ratoon stunting disease (RSD), a bacterium that lives inside the cane and shows almost nothing outside. It spreads by the cutting knife and infected setts. Restart from hot-water-treated, disease-free seed, disinfect your cutting tools, and don’t keep ratooning an infected crop — that is how RSD is broken.
How can a disease with no symptoms cause big losses?
Precisely because it is hidden. RSD stunts the cane and thins the crop without the obvious spots, wilting or rots of other diseases, so growers mistake it for poor soil or management and keep ratooning — while the bacterium spreads through the knife and setts and the yield quietly declines ratoon after ratoon. The cumulative loss can be large. That invisibility is why hot-water-treated clean seed and tool hygiene, not visual scouting, are the control.
Why does hot water treatment help against ratoon stunting?
Because the RSD bacterium lives inside the seed setts’ vascular tissue, and hot water treatment (HWT) at the recommended temperature and duration frees the setts of it before planting. Since the disease is spread mainly through infected seed and the cutting knife — not insects or soil — starting from HWT-treated seed from a clean nursery, and disinfecting cutting tools, is the whole basis of control. Confirm the HWT schedule 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.