Submitted by kanchannainwal1 on Wed, 19/08/2009 - 10:06
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Ratoon Stunting Disease:
- Ratoon stunting disease has been considered to be an important cause for sugarcane varietal degeneration.
- Primary spread of disease is through infected setts.
- Secondary spread is through contaminated harvesting implements.
- Ratoon crop suffers more damage due to RSD than the plant crop.
- Disease is known to reduce germination and yield.
Fig: Ratoon stunting Disease
Symptoms:
- The presence of pin head like orange coloured dots of bacteria on the internal soft tissue in the nodal region.
- Stunted growth, thin stalks with short internodes; pale yellowish foliage and rapid tapering of the stem towards the top are other symptoms.
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Ratoon stunting disease of sugarcane
This disease appeared as ‘Q 28 syndrome’ in Australia in 1944-45 (a collection of Q28 gave better ratoon whereas another collection failed miserably, as if it was mixture of two genotypes). Initially, it was thought of viral origin but researches have conclusively demonstrated its bacterial etiology. It is caused by a fastidious xylem limited Gram positive bacterium Leifsonia xyli subsp. xyli (=Clavibacter xyli sub sp. xyli).
In India, the presence of the disease was felt only when Prof. Chilton, who visited India as a delegate to attend IX ISSCT Congress (1956), detected it in CoS 510 at Jamnabad farm, Golagokarnath However, its presence in India was actively debated as most of the experiments conducted subsequently in India was not of affirmative nature and the nodal symptoms were elusive/ephemeral. Later on, Dr. Kisan Singh confirmed the presence of RSD from a collection of deteriorating Co 290, obtained from Jaora Sugar Mill area, Jaora (M.P.). He splited the affected canes vertically and treated one half with hot air treatment at 540C for 8 hours and untreated half acted as control. This conclusively demonstrated the curing effect of heat treatment and the presence of RSD. Hereafter, a number of genotypes including the wonder cane Co 419, Co 453, Co 213, Co 312, Co 740, Co 997, CoL 9, BO 22 etc., were reported to be inflicted with the disease. Of late, it has been observed that most of the popular cane genotypes are in cultivation are carrying substantial amount of RSD bacterium. The predominant varieties of subtropical India like BO 91, Co 1148, Co 1158, Co 62399, CoH 56, CoH 72, CoJ 64, CoJ 84291, CoS 767, CoS 88216, CoS 90269, CoS 95255, CoLk 7901, CoPant 84211, CoPant 84212, CoPant 90222, CoSe 92423, etc. are in the clutch of RSD. In fact, no cane area in India is free from the RSD menace; wherever a conscious search was made, its presence was immediately become apparent. This disease is now recognized as the most important bacterial disease of sugarcane in India causing substantial loss in cane yield.
The name ‘ratoon stunting disease’ is a misnomer as it is not restricted to the ratoon crop. The disease affects both plant and ratoon crops but its detrimental effect is more pronounced in the latter. In the absence of proper symptoms of the disease, diagnosis of the disease at the field level is exceedingly difficult. In some varieties/clones, pink/orange coloured vascular bundles appear at the nodes, when canes are sliced longitudinally with a sharp knife. The pin-head type symptoms appear reddish coloured on the yellowish white background of the nodal tissues. The damaging nature of the disease is not fully appreciated because the diseased plants look apparently healthy and, in most cases, healthy plants are not available for comparison. The pathogen spreads through the infected setts. Mechanical transmission by the sett cutting and harvesting implements is mainly responsible for the spread of this pathogen. As the disease cannot be detected by the external symptoms, the bacterium spreads surreptitiously defying all the barriers.