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THE CROP DISEASES OF SIKKIM
HIMALAYAS |
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CROP: GINGER
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Scientific Name |
Zingiber officinale Rosc. |
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State/World wide |
Sikkim, Darjeeling, Arunachal Pradesh,
Asia and South East Asia
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Common Name of Disease:
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2.
BACTERIAL WILT |
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Local Name of Disease |
-Ohelini bimar or’Prem rog |
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Causal Organism |
-Ralstonia
solanacearum |
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Distribution of Disease in Sikkim
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-Disease incidence in maximum in high rainfall areas of
North, East, and some areas of West Sikkim and less in South
Sikkim.
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Disease Incidence |
-Moderate to high |
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Site of Infection |
- The bacteria
find their way to the roots of ginger by swimming in soil
water. They enter the roots through the wound caused by
nematode or mau extraction. Once inside the roots, they
enter the water conducting tissues and via these they travel
to the rhizome and the stem.
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Dissemination of the Disease |
- It is a seed-borne and
soil borne disease. |
Symptoms
Symptom is noticed
during July-August in Sikkim. In severe
cases result in total loss of crop.The
disease is characterized by drooping and
wilting of leaves even in early morning. The
base of the pseudostem turns grey to dark
and soft. The cut ends of the pseudostem or
rhizomes when pressed exude a milky
substance. The leaf margin of the affected
plants exhibits yellow bronze coloured
symptom and they curl backward. Ooze test
positive confirms that it is bacterial wilt.
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Favourable environmental condition for
disease
Water stagnation in the field during rainy
season.Hot and humid weather condition favours the disease
incidence. Injury caused to the rhizome during mau
extraction makes the plant susceptible to the disease.
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Mode of
Transmission
Disease is
transmitted to a healthy plot through infected planting
material, mechanical transmission through human activities.
Drainage / run off water flowing across the diseased plot
carrying fungal spores to a non-contaminated plot at the
lower elevation.
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Life cycle of
Organism
Plant Protection Measures: Seed
should be selected from a diseased free source. Fresh land
free from disease inoculums should be selected based on
previous history. Crop rotation of 4-5 years should be
followed to avoid disease incidence.
Crop rotation should not be done with solanacous crop like
tomato, potato, chilly, brinjal etc. Rather growing
Cruciferous crop like mustard, radish would suppress the
pathogen.Planting should be done on raised bed with proper drainage.
Thick mulching should be provided to check weed growth and
to conserve moisture. FYM should be well decomposed to avoid
white grub infestation. Planting of ginger should be done on
sloppy land to avoid water stagnation. Seed treatment with
Trichoderma spp.+Pseudomonas florescens before sowing can
control disease.
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Brief
history of the disease
Pseudomonas
solanacearum (Smith) (which is now renamed as Ralstonia
solanacearum) Smith 1914 is a soil borne pathogen which
typically invade a host via root injuries or at the point of
emergence of the root hairs and lateral roots. Some evidence
has been presented of the organism’s ability to enter leaves
of certain host via stomata. Bryan (1915) infected
nasturtium leaves with a suspension of R. solanacearum and
recently we showed that naturally occurring leaf spots of
capsicum was caused by R. solanacearum (Hayward & Moffett
1978).In India, rotation with finger millet or maize was effective
in reducing wilt of eggplant and tomato (Shoe et al 1981).In china, 3 years of rice cultivation reduced bacterial wilt
incidence of ground nut from 83% to1.5% (Wang et al 1983).
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| Bioinformatics Sub- DISC, SSCS&T |
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