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An Expert System for Disorder Diagnosis in Sugarcane Crop


Sugarcane Disease Symptoms

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, GSD, RSD and sett rot are the important diseases causing yield loss of varying magnitude in different states. 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 support 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.
  • 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. 

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