Grassy shoot (sugarcane)
The clump becomes a mass of thin, white-to-pale, grassy tillers with no cane — a seed-borne phytoplasma stopped by clean seed and heat treatment.
- Pathogen
- Phytoplasma (grassy shoot)
- Spreads by
- Infected seed setts; some insect vectors
- Favoured by
- Planting infected setts; diseased ratoons
- Main risk
- Grassy tillers, little or no millable cane
Overview
Grassy shoot disease (GSD) is an important phytoplasma disease of sugarcane. Its signature is a dramatic change in the clump: instead of a few thick canes, the stool throws up a mass of thin, weak, profusely-tillering shoots with narrow, chlorotic (white to pale yellow or cream) leaves, giving a grass-like or bushy appearance. Such stools form little or no millable cane, so the loss is direct and severe.
It is spread mainly through infected seed setts (the phytoplasma is carried in the planting material), and can also be transmitted by certain sap-sucking insect vectors. Because the primary spread is seed-borne, control rests on healthy, disease-free seed, seed treatment by moist hot air or hot water (MHAT/HWT) to free the setts of the phytoplasma, roguing affected clumps, and not ratooning or taking seed from a diseased crop. There is no curative spray for an affected stool.
How to identify it
- A stool throwing up a mass of thin, weak, profusely-tillering shoots instead of a few thick canes.
- Narrow, chlorotic leaves — white to pale yellow or cream — giving a grass-like, bushy look.
- Little or no millable cane formed from affected stools.
- Affected clumps standing out as pale, grassy patches among healthy dark-green cane.
What causes it and when
- A phytoplasma, carried mainly in infected seed setts (planting material) and also transmitted by some sap-sucking insect vectors.
- Planting setts from a diseased crop is the main way it enters and spreads a new planting.
- Ratooning a diseased crop carries the phytoplasma forward into the next crop.
- Once a stool is affected it stays diseased — there is no recovery of that clump.
Cultural & organic control
- Take seed setts only from a healthy, disease-free crop/seed nursery; never from a grassy-shoot field.
- Rogue out and destroy affected clumps as soon as seen, and do not ratoon a diseased crop.
- Grow tolerant varieties where available and maintain a certified healthy seed nursery.
- Manage sap-sucking insect vectors as part of the package.
Chemical / seed treatment
- Treat seed setts by moist hot air treatment (MHAT) or hot water treatment (HWT) at the recommended temperature and time to free them of the phytoplasma — the key control.
- There is no curative spray for an already-affected stool — control is preventive and seed-based.
- Manage insect vectors with recommended insecticides where they contribute to spread.
- Confirm the current MHAT/HWT schedule and variety recommendation for your area with your local KVK/cane research station.
Prevent it coming back
- Base every planting on healthy, heat-treated seed from a clean seed nursery.
- Do not ratoon or take seed from a grassy-shoot-affected field, and rogue affected clumps promptly.
- Maintain the three-tier healthy seed programme and manage vectors to keep new plantings clean.
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
Some of my sugarcane stools are all thin white grassy shoots with no cane. What is it?
That mass of thin, weak, profusely-tillering shoots with white-to-pale leaves and no millable cane is grassy shoot disease, caused by a phytoplasma. It is spread mainly through infected seed setts. There is no cure for an affected stool, so rogue and destroy them, do not ratoon or take seed from that field, and next season plant heat-treated (MHAT/HWT) seed from a healthy seed nursery.
Why does hot-water / MHAT seed treatment help against grassy shoot?
Because the phytoplasma that causes grassy shoot is carried inside the seed setts, and moist hot air (MHAT) or hot water (HWT) treatment at the recommended temperature and duration frees the setts of it before planting. Since the disease spreads mainly through seed, treating the setts — and taking them from a healthy seed nursery in the first place — is the single most effective control, because there is no cure once a stool is affected.
Can I ratoon a field that has some grassy shoot?
It is best not to. Ratooning a diseased crop carries the phytoplasma forward, so the next crop starts already infected and the disease builds up. Instead, rogue and destroy affected clumps, avoid ratooning a diseased field, and replant with heat-treated, disease-free seed from a healthy seed nursery. Combine that with managing insect vectors and growing tolerant varieties for lasting control.
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.