Split a stalk lengthwise and look. If it is red inside with white patches across it and a mild sour smell, it may be red rot. Do not take setts from such a field, do not keep a ratoon, do not let its water go into another field, and show it to an agriculture officer right away.
First job: split a stalk and look
Walk through the field and look for clumps that are turning yellow or drying. Cut 2 to 3 stalks from those clumps and split them lengthwise. Check the waterlogged part first.
- Leaves: Leaves turn yellow, dry and die.
- Leaf midrib: Small brown to red spots on the upper and lower sides.
- Inside the stalk: Red colour with white patches running across it. This is the main sign.
- Smell: On splitting, a mild sour, starch-like smell may come.
- Late stage: Stalks break easily at the nodes.
How does red rot spread?
According to a review by ICAR-SBI scientist R. Viswanathan, infected setts are the main source. Even in a stalk that looks healthy from outside, infection can stay dormant in the node and pass to the next crop. The fungus can also survive in soil, stubble and crop residue. It spreads through the field by rain, irrigation water and wind. Cool, wet weather, heavy soil, waterlogging and growing the same variety again and again raise the risk. Water shortage can also weaken the crop further.
What to do now if you suspect it?
- Setts: Do not take seed from this field at all. Do not give it to another farmer either.
- Ratoon: Do not keep a ratoon in a diseased field.
- Water: Take care that its water does not go into another field. Keep drainage good.
- Stubble and trash: Clean the field. Ask an agriculture officer how to dispose of the residues.
- Crop rotation: Take another crop for at least 2 years, and plough to expose the soil to the sun.
- Variety: Find out from an agricultural university which current variety for your area can withstand red rot. Because there are different types of the fungus, a variety's resistance can change.
Can chemicals save the field?
Do not rely on chemicals for red rot in a standing crop. The Pacific Pests, Pathogens and Weeds guide does not consider chemical control economical. The main remedies from scientists are healthy seed, avoiding waterlogging and resistant varieties. For sett treatment and choice of pesticide, ask your local agriculture officer.
Before the next planting
Take setts only from a healthy, checked field. For details, read Sugarcane planting.
Questions and answers
Can a ratoon be kept in a field with red rot?
No, the advice is not to keep a ratoon in a diseased field, because fungus in the stubble can infect the new shoots.
Is all red sugarcane red rot?
No. If the red colour comes with white patches across it and a sour smell, the suspicion is stronger. Get it confirmed by an agriculture officer or agricultural university.
Sources: Viswanathan R. (ICAR-SBI): Red rot of sugarcane, CAB Reviews 16(023), 2021 · Pacific Pests, Pathogens and Weeds: Sugarcane red rot
*Farmers' results are their own experience, not a guarantee. Results change with soil, water, weather and care.
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