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Agricultural crops :: Cash crops :: Sugarcane

Red rot: Glomerella tucumanensis

Symptoms:            
  • The affected canes exhibit leaf colour change, from green to orange and then to yellow in the third or fourth leaf. Then the leaves start drying from bottom to top.
  • If the fungal spores enter the leaf sheath through the leaf midrib, then reddish spots can be seen on the back side of the leaf midrib also.
  • The external symptoms appear only after16 - 21 days after infection and drying of entire cane takes another 10 days time.
  • When the affected cane is split opened, the inner region is reddish in colour with intermittent white tinges across the cane length.
  • Sometimes, the pith inside the cane is filled with blackish brown liquid and exhibited alchohol odour.
     
 

Reddish lesion on leaf midrib

  Orange to yellow leaf   Inner region with reddish colour
Pathogen:
  • Red rot disease is caused by the fungus Glomerella tucumanensis. An older name, Colletotrichum falcatum, is still preferred by some pathologists.
  • Pathogen present on leaf sheaths and blades, solitary or aggregated, often forming short lines between vascular bundles, globose, immersed, dark brown to black 65-250 µm dia.; wall up to 8 cells thick, sclerotia on outside, pseudoparenchymatous within, ostiole slightly papillate, circular.

Management strategies:

Cultural method:

  • The best way to control red rot is to select setts for planting from healthy plants in a disease- free area.
  • The red rot affected field must be rotated with rice for one season and other crops for two seasons.
  • Growing of recommended resistant and moderately resistant varieties viz., Co 86032,  Co 86249, CoSi 95071, CoG 93076, CoC 22, CoSi 6 and CoG 5
   
  Glomerella tucumanensis  

Physical method:

  • Removal of the affected clumps at an early stage and soil drenching with  Carbendazim 50 WP (1 gm in 1 litre of water)
  • The cut ends and entire setts should be dipped in a fungicide solution, such as one per cent Bordeaux mixture.
  • If the disease is noticed in the field, the leaves and canes should be collected and destroyed by burning.

Chemical method:

  • Adopt sett treatment with Carbendazim before planting (Carbendazim 50 WP (0.5 gm in 1 litre of water) or Carbendazim 25 DS (1gm in 1 litre of water) along with 2.5 kg of Urea in 250 litre of water
  • Use fungitoxic chemicals like Bavistan, Benomyl, Topsin and Aretan at 0.1 per cent for 18 min. at 52ºC for dipping setts which gave almost complete elimination of rot infection.
Content validators: 
Dr. T. Ramasubramanian, Senior Scientist, Sugarcane Breeding Institute, Coimbatore-641007.
Dr.V. Jayakumar, Senior Scientist, Sugarcane Breeding Institute, Coimbatore-641007. 
Dr.M. Ravi, Assistant Professor, Sugarcane Research Station, Sirugamani, Trichy- 639115.

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