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FAQ on Sugarcane Diseases

Disease symptoms

Symptoms of sugarcane diseases

Different kinds of pathogens viz. fungi, bacteria, viruses and phytoplasma cause diseases in sugarcane. More than 50 diseases were reported in the country. We had severe outbreaks of different diseases in the past and incurred heavy losses. Still diseases pose a challenge to sugarcane cultivation  in different parts of the country. Diseases such as red rot, smut, wilt and sett rot are the important diseases causing yield loss in different states, diseases caused by bacterial, viral and phytoplasmal agents pose serious threat to the crop under specific situations. Sugarcane pathogens systemically infect sugarcane and over the years the varieties degenerate due to the systemic colonization of different pathogens. Vegetative propagation favours carry over of the pathogen to the new crop; and cultivation of the crop throughout the year favour infection of one or other pathogens. Although there are common symptoms pronounced by various pathogenson in sugarcane, they can be easily distinguished by following a scientific approach to diagnosis. The following sections are meant to clarify doubts of the sugar industry personnel and farmers on sugarcane diseases to easily identify the diseases and to take up immediate management strategies.

  • Yellowing of foliage is the first symptom to be noticed by a grower when the stalk or leaves are infected by the pathogen(s).
  • If Yellowing in germinated shoots is noticed, then it may be due to sett rot or red rot.
  • In case of sett rot, setts would be rotten with reddish discolouration of internal tissues and emitting a rotten pineapple odour. Blackening of the affected setts would also be noticed. 
  • In case of red rot, the shoots will be intact with lesions in the whirl and setts of such canes do not emit the pineapple odour.
  • Early shoot borer infestation also shows drying of spindle leaves with dead-heart symptoms. Unlike red rot the damaged spindle can easily be pulled out in this case.

More on Symptoms

Sugarcane disease symptoms (contd..)

  • Yellowing of leaves during cane formation stage and later red rot and wilt affected canes would show initially yellow or orange discolouration of entire leaves of 3 to 5 position from the top and later all the leaves in a cane (or clumps depending on the severity) would show such discolouration. Only after splitting the canes with such foliar discolouration exact identity of the disease can be established. 
  • In case of red rot, reddening of ground tissue with characteristic white spots will be there 
  • In case of wilt, the white spots as in red rot will be absent. Further, wilt affected cane would show pithiness with boat shaped cavities with reddish brown discolouration of internal tissues. 
  • If yellow leaf disease (syndrome) is there, yellowing of mid ribs in the 3 to 5 leaves from top during and after cane formation stages will be noticed. Later laminar yellowing along the discoloured mid rib and drying of leaf along the mid rib from the tip will be observed. Further in the affected canes internodal elongation gradually decrease and show bunching of leaves in the apex. 
  • In case of leaf scald, a bacterial disease, whitish yellow or white coloured pencil line-like longitudinal streaks running to entire leaf length of the leaf is seen. Usually these lines will be parallel to midrib and subsequently drying of leaves along the discoloured region will be there. 
  • In all these diseases marginal drying of leaves will not be seen as in the case of physiological disorders. 
  • In case of severe mosaic, entire laminar region turn pale yellow with pale or dark green islands. Often, these leaves also show gradual drying. Sometimes, root borer or termite infestation also show drying of entire cane with foliage. Here the pulled out canes would reveal the borer / termite damage. 

Red rot

FAQ- Red rot disease

Photo Gallery of Red Rot Disease (Click this link)

  1. At what stages of the crop the disease is expected?
    • The disease occurs in all the stages of crop in the field from germination to harvest.
  2. What are the typical symptoms?
    • Orange / yellow discolouration of leaves followed by drying of canes in a clump. External rind discolouration as dull brown patches on nodes and internodes. Splitting of the canes reveal the typical reddening of internodal tissues with intermittent white spots. At later stage mycelial growth is seen in pith region.
  3. What type of symptoms can be seen on leaves?
    • Usually leaves in the infected canes show orange to yellow discolouration before drying. In highly susceptible varieties reddish brown lesions on the mid ribs can be seen.
  4. How it affects the crop yield?
    • Infected stalks result in death of canes, leading to reduced cane yield. Inversion of sucrose into glucose and  fructose due to pathogenic invertases cause loss in sugar recovery.
  5. How to identify disease infection in seed canes?
    • While cutting partially infected canes cut ends will show reddening and nodal region may show nectotic patches.

More FAQs on red rot...

More FAQs on Red rot disease

  1. Will it cause more damages in ratoon?
    • Yes. Since the initial inoculum to cause the disease is high, more damage to the crop is noticed in ratoon crop than in plant crop. However, in case of epidemic situations plant crop also suffers more damage.
  2. Does the pathogen survive in the soil?
    • Yes. It survives for a limited period in the soil, but in the leftover infected stubbles it  survives for many months.
  3. In which season the disease spread fast?
    • During monsoon seasons the spread is more
  4. What are the factors enhancing disease severity?
    • Monsoon months with cyclonic winds favour spread of the disease very fast. Flooding of  sugarcane fields over large areas favour dispersal of inoculum through flood water. Even a limited seed cane infection favours disease build up in plant and ratoon crops.
  5. What are the resistant varieties available for cultivation?
    • Co 86032, Co 86249, Co 93009, Co 94008, Co 97008, Co 99004 and Co 99006.

More FAQs on red rot...

More FAQs on Red rot disease..

  1. Is it advisable to plant sugarcane in red rot affected fields?
    • No. Once red rot infection is noticed, plantihg of susceptible sugarcane varieties should not be done. If resistant varieties are available planting can be taken up.
  2. What is to be done after noticing the first symptoms?
    • The infected dumps should be uprooted and burnt imme,diately to prevent spread of inoculum. Uprooted areas should be drenched with 0.05% Carbendazim to arrest the inoculum spread.
  3. What is the effectiveness of fungicide control?
    • Spraying of fungicides is not effective since the pathogen is deep seated in the cane. Dipping of setts in systemic fungicides before planting will help to prevent soil-borne infection in causing disease in the germination phase.
  4. Can we cultivate red rot susceptible  varieties with proper plant protection methods?
    • Yes. It can be cultivated in red rot free areas. By practicing integrated approaches of clean seed, field hygiene, disease surveillance and water management it can be controlled  effectively. However it is suggested to avoid susceptible varieties in epidemic situations.
  5. What care can to be taken in seed nurseries?
    • The nursery crop should be raised in red rot free area. In any case red rot infected fields should not considered for seed purpose. The seed crop should be monitored regularly to ascertain that it free from the disease.


FAQ - Smut disease

Photo Gallery of Smut Disease (Click this link)

  1. What are the diagnostic symptoms in the field?
    • Conversion of growing apex region into a blackish whip-like structure containing millions of black powdery spores covered by translucent white silvery membrane.
  2. When the symptoms will be manifested?
    • The symptoms can be seen at all the stages.  More symptoms can be seen during cane formation. In ratoons symptoms can be seen much earlier. In severe cases sprouts from the ratoon would show whips.
  3. Why the smut affected canes show whips?
    • Smut fungus infects the cane systematically including apical meristem. After infecting apical meristem, the fungus converts the growing shoot into a whip-like structure with millions of smut spores covered with silvery membrane.
  4. How does the disease spread?
    • Primary transmission takes place through infected seed canes. In the field through air the spores from the whips are transmitted from cane to cane in the field.
  5. Why do the affected canes turn bushy?
    • Since the pathogen infection in the meristem breaks the apical dominance numerous side shoots are induced in the smut infected plant, which gives the bushy appearance.
  6. At what situations smut causes severe yield losses?
    • When severe smut infection occurs during early stage of the crop of the ratoon, significant yield reduction is expected.
  7. Is it amenable for heat therapy?
    • Yes. Hot water combined with fungicide (Tridimefon 0.1%) at 52oC; 30 min effective in eliminating pathogen infection in the setts.
  8. Can the affected crop be ratooned?
    • Crop showing more than 2.0% of smut infection should not be ratooned.
  9. Up to what level of disease seed selection can be permitted?
    • Up to 1% smut infection level the seed selection can be permitted.


FAQ - Wilt diseases

  1. What are the diagnosable symptoms?
    • External - gradual yellowing and drying of foliage,shrinkage and withering of canes.
    • Internal - infected canes show light to dark reddish brown discolouration of ground tissue, pithiness and boat shaped cavities in the middle of the internode.
  2. How to differentiate the stalk symptoms with red rot?
    • Reddening of ground tissue with characteristic white spots as red rot are absent in case of wilt. Further wilt affected cane would show pithiness with boat shaped cavities with reddish brown discolouration.
  3. Whether sugarcane is infected by both red rot and wilt same time?
    • Yes. Such canes show symptoms of both the diseases.
  4. What aggravates wilt severity?
    • Extended drought in the summer followed by water logging in the monsoon. Damages to roots, especially by root borer and other root pests increase wilt severity.
  5. How to control wilt?
    • Healthy seed, crop rotation, optimizing soil moisture status and reducing root borer infestation are recommended to control wilt in an integrated approach.

Sett rot

FAQ - Sett rot disease

  1. Why the germination phase is vulnerable to sett rot infection?
    • Surviving pathogen in the soil enters the sett tissue through cut ends and causes rotting if they are not protected with fungicide. Delay in germination due to deep-planting or water stagnation in the field enhance the chances of pathogen entry into the setts and pathogenesis.
  2. Is sett rot amenable for fungicide control ?
    • Yes. Dipping of setts in the fungicide solution (Carbendazim, 0.05%) protects the cut ends from the surviving fungus in the soil.
  3. How to prevent sett rot disease?
    • Avoiding deep planting during monsoon and preventing water stagnation during germination phase. Dipping of setts in fungicide has to be done as a prophylactic measure before planting.

Grassy Shoot

FAQ - Grassy shoot disease

  1. What pathogen is responsible for the grassy shoot disease?
    • Phytoplasmas.
  2. What are the characteristic symptoms of grassy shoot disease?
    • Profuse tillering with lean, lanky and chlorotic tillers. Stunting of affected canes with axillary bud sprouting.
  3. How to differentiate grassy shoot disease symptoms with other common deficiency symptoms?.
    • Excess tillering with chlorotic leaves (partial or complete) is the typical symptom of GSD. In deficiency symptoms the excess tillering will not be seen. Further the axillary buds show sprouting only in GSD affected canes. Chlorosis due to iron show recovery of symptoms when sprayed with ferrous sulphate whereas in case of GSD no recovery will be there. Further, GSD appears in isolated clumps whereas chlorosis due to deficiencies appears in patches.
  4. Why is grassy shoot disease more severe in ratoons?
    • Due to low pathogen load in plant crop, the crop suffers less. Once ratooned, the pathogen in the stubbles initiates disease in the newly emerging shoots and such clumps will not any millable canes.
  5. How does the pathogen of grassy shoot disease spread?
    • Infected seed cane serves as primary source and insect vectors spread the pathogen cane to cane in the field.
  6. Is grassy shoot disease amenable for heat therapy?
    • Yes. Aerated steam therapy (AST) eliminates the pathogen in the seed canes.


FAQ - Yellow Leaf Disease(syndrome)

  1. What are characteristic symptoms of yellow leaf disease (syndrome)?
    • Yellowing of mid ribs in the 3 to 5 leaves during and after cane formation stages. Laminar yellowing along the discoloured midrib and drying of leaf along the midrib from the tip.
  2. Will yellow leaf disease (syndrome) affect the crop yield? If so to what extent?
    • The disease affects cane yield significantly in susceptible varieties as well as in uncared fields. Expression of the disease in the early stage would cause more damages to the crop. In the affected canes inter-nodal elongation gradually decrease and show bunching of leaves in the apex. In addition to loss in cane yield, sugar recovery is also affected in the infected canes.
  3. How does the yellow leaf disease spread?
    • Through infected seed canes and insect vectors.
  4. How to control the yellow leaf disease (syndrome)?
    • Through meristem tip culture, the virus can be eliminated from the cane. Later proper seed nursery programmes are to be followed to ensure supply of disease free seed canes.


FAQ - Ratoon Stunting disease (RSD)

  1. Does ratoon stunting affect ratoon crop only?
    • No. It also affects plant crop. But the severity is more in ratoons.
  2. How the ratoon stunting disease (RSD) can be recognized in the field
    • Slow decline of varietal performance with cane thinness and poor vigour.
  3. Is there any diagnosable symptoms of ratoon stunting disease?
    • Reddening of nodal tissue (internal) in the form of streaks, dots or commas. No symptoms can be seen in internodes.
  4. Why the canes become thin due to RSD?
    • The pathogenic bacterium systemically colonizes the xylem vessels. If the same seed source is used for many years the pathogen titre increases and causes decline in varietal performance.
  5. How does the ratoon stunting disease spread?
    • Through infected seed canes and left over crop debris in the field.
  6. What are the suggested control measures for ratoon stunting disease?
    • Aerated steam therapy (AST) eliminates the pathogen from the infected canes. Use of disinfectants to clean seed cane cutting tools would reduce chances of spread of pathogen from infected to healthy setts.


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ICAR-Sugarcane Breeding Institute
Sugarcane Institute Rd,
Karumalai Chettipalayam, Veerakeralam,
Coimbatore 641007
Tamil Nadu

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2023-01-30 18:15