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Agricultural crops :: Cash crops :: Sugarcane
Sugarcane Diseases

Red Rot - Colletotrichum falcatum

Sett Rot or Pine Apple Disease - Ceralocystis paradoxa, Ceratostomella paradoxa

Grassy Shoot Disease - Virus

Ratoon Stunting - Bacterium

Mosaic Disease - Sugarcane Mosaic Virus



Red Rot : Colletotrichum falcatum

Symptom
Healthy leaf 
Red rot affected leaf 
Infected sett
  • The first symptom of red rot in the field is discolouration of the young leaves. The margins and tips of the leaves wither and the leaves droop.
  • The discolouration and withering continues from the tip to the leaf base until the whole crown withers and the plant dies, within 4 to 8 days.
  • In a single stool, most of the stalks may wither almost simultaneously.
  • As the disease advances the entire stem rots and the central tissues become pithy.
  • The tissues are reddened throughout the basal portion, especially the vascular bundles, which are intensely red; there may be cross-wise white patches interrupting the reddened tissues.
  • The internodes may shrink and when such canes are split open large cavities may be found in the centre and the pithy tissues may appear brown. Often a profuse whitish growth of the fungal mycelium may be found in the brown background of the host tissue.
  • In some cases, black, minute, velvety bodies, representing the acervuli of the fungus, may also be seen Since reddening is a common symptom of other diseases of sugarcane, the white patch symptom is an important diagnostic characteristic of red rot.
  • In the infected plants the leaves may show symptoms in the form of dark red lesions in the mid-rib, which may elongate, turning blood-red with dark margins and later on with straw-coloured centres.
  • In the older lesions minute black dots, representing the acervuli, can be seen. Often the infected leaves may break at the lesions and hand down

Management
  • Following good cultural practices such as clearing fields of excessive trash and ensuring efficient drainage.
  • Healthy setts only are to be planted to avoid poor plant stand due to rotting.
  • Affected fields should be isolated through bunding to prevent movement of water to adjacent fields.
  • Rattooning of infected fields should be strictly avoided.
  • Crop rotation in the affected fields could reduce disease inoculum.
  • Sett treatment with 0.1% Carbendazim or 0.05% Triademefon for 15 min.
  • By far the most effective measure for management of red rot is use of resistant varieties for cultivation. Varieties viz. Co 62198, Co 7704 (Resistant), CoC 8001, Co 8201 (moderately resistant).




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Sett rot or Pine Apple disease: Ceralocystis paradoxa,Thielaviopsis paradoxa

Symptom
Infected crop
Healthy crop
Chemical for sett treatment 
  • The disease primarily affects the sugarcane setts.
  • When diseased setts are planted they may rot before germination, or the shoots may die after reaching a height of about 6-12 inches.
  • If infected shoots survive, they are very much stunted and chlorotic.
  • Eventually the leaves may wither and the shoots wilt.
  • If the affected shoots and setts are examined the central portion of the shoots will be seen discoloured red and the contents of the sett rotting.
  • A characteristic pineapple smell is associated with the rotting and hence the name.

Management
  • Healthy setts should be obtained from disease-free field.
  • They should be carefully selected and treated with 0.1% Carbendazim before planting, to protect the cut-ends from invasion by the fungus.



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Grassy Shoot:Virus

Symptom
  • The disease is characterized by proliferation of vegetative buds from the base of the cane giving rise to crowded bunch of tillers bearing narrow leaves.
  • The tillers bear pale yellow to completely chlorotic leaves.
  • Cane formation rarely takes place in affected clumps and if formed the canes are thin with short internodes.
  • The virus is readily transmitted by sap inoculation and in the field it is transmitted through infected setts and perpetuated through crop ratooning. The aphids are the vectors for this disease.


Management
  • The disease is controlled by eradication of diseased parts as soon as symptoms are noticed
  • Avoid selection of setts from diseased area
  • Pre-treating the setts with aerated steam at 50o C for 1 hour before planting



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Ratoon Stunting: Clavibacre xyli sp. xyli

Symptom
  • This is a xylem limited bacterial diseases of sugarcane found in some parts of India in recent years.
  • The affected plants are stunted, the stunting being most severe in stubble and ratoon crops.
  • The setts taken from diseased plants germinate poorly and the few shoots that emerge grow very slowly.
  • RSD bacterium spreads through infected setts and harvesting implements.

Healthy plant 

Infected leaf


Management
  • The disease spreads mainly through planting material, setts should be selected from healthy plants.
  • Treating the setts in hot water at  50C for about 2 hours.



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Mosaic: :Sugarcane mosaic virus (SCMO)

Symptom


  • Mosaic patterns with contrasting shades of dark and light green patches appear on leaf.

Healthy plant 

Infected leaf


Management
  • Roguing infected plants and chemical sprays to kill the insect vectors are also advocated.
  • However, the most practical method of controlling the disease is to grow mosaic-resistant or, at least, tolerant varieties.


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