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Leaf scald disease in sugarcane

Submitted by kanchannainwal1 on Wed, 19/08/2009 - 10:20
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Leaf Scald

Causal organism: Xanthomonas albileneans

  • It is a bacterial disease, widely spread in many countries.
  • Disease is favoured by wet seasons, water stress due to drought, water logging and low temperatures.

Symptoms:

  • Disease symptoms appear in two phases, the chronic and acute phases.
  • In the chronic phase, "white pencil line" extending entire length of lamina reaching the margin of young leaves and stripes diffuse later resulting in leaf etiolation. Drying from tip onwards presents a scalded appearance. Different degrees of chlorosis from total albinism to interveinal chlorosis in young leaves during summer, germination of buds in acropetal manner with bushy appearance in standing cane, cut open stalks showing dark red vascular strands, prominent streaks at node invariably in the side shoots, are other prominent symptoms of chronic phase.
  • In the acute phase the symptoms appear suddenly and die without any major leaf symptoms. The masking of symptoms is more common during monsoon and symptoms may appear suddenly any time during crop growth.
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 Leaf scald disease of sugarcane

Submitted by duttamajumder on Mon, 17/12/2012 - 12:17.

 Leaf scald is a bacterial disease that has made its impact in the country in recent years. In India, it was first recorded in April 1961 by Egan during his short stay at I.A.R.I., New Delhi. However, this disease remained almost unnoticed till 1974 when it was reported from Anakapalle (A.P.). Hereafter, the disease has been recorded from different north Indian States, like Punjab, Haryana, Bihar, Uttar Pradesh, Uttarakhand and natural occurrence of this disease was noticed in several commercial genotypes. Prominent among the susceptible genotypes are BO 17, BO 70, BO 90, BO 109, Co 419, Co 1158, Co 62399, Co 7301, Co 8312, Co 8315, Co 8334, Co 93016, CoS 767, CoS 90269, CoLk 7710, CoLk 7901, CoLk 8001, CoLk 8102, CoLk 8901, CoJ 64, CoJ 81, CoH 56, CoH 72, CoH 92201, CoH 94201, CoPant 84211, CoPant 84212, CoPant 84213, ISH 40, etc. The disease is caused by the bacterium Xanthomonas albilineans. There are two distinct phases of the disease viz. (i) chronic phase – the most common phase, (ii) acute phase/ wilting phase – it is of rare occurrence. The distinguishing symptom of chronic phase appears on the leaf as a ‘white pencil line’. The white lines are prominent in young leaves. Usually one or two vascular bundles turn albino and appear as white line. This is due to the effect of toxin ‘albicidin’ produced by this pathogen. The ‘white pencil line’ increase sideways with age and depending on the prevailing weather conditions scalding/drying of the leaves takes place. Occasionally some patches of red area may occur on the white pencil line. The other most conspicuous symptom of the disease is the development of side shoots (germination of buds) in an acropetal fashion. The crown of the affected plants show inward curling of leaves and in canes having severe infection die prematurely.

The disease spreads mainly through the infected setts. Xanthomonas albilineans is notorious for its latency and has spread surreptitiously in different areas defying even the most ‘vigilant eye’. Mechanical transmission by harvesting and sett cutting implements is the most important mode of dissemination of this pathogen. Transmission through fluff (true seed) has also been reported. Depending on the intensity and type of infection the disease may assume serious proportion.