yvm of okra

8/8/2019 YVM of Okra

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YELLOW VEIN MOSAIC OFYELLOW VEIN MOSAIC OF

OKRAOKRA

PRESENTED BY:PRESENTED BY:--

HANSRAJ SINGH(2005HANSRAJ SINGH(2005--AJAJ--44)44)

KUKIL SARMAH( 2005KUKIL SARMAH( 2005--AJAJ--55)55)


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INTRODUCTIONINTRODUCTION

The effect of virus and virusThe effect of virus and virus--like diseases on thelike diseases on the

aboveabove--ground morphological yield componentsground morphological yield components

of okra was determined in farmers fields in Juneof okra was determined in farmers fields in June

2001.2001.

Compared to healthy ones, diseased plant heightCompared to healthy ones, diseased plant heightwas reduced by 19.5%, number of fruits bywas reduced by 19.5%, number of fruits by

34.7% and petiole length by 32.1% .34.7% and petiole length by 32.1% .


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The first time it has been identified in the LakeThe first time it has been identified in the Lake

Victoria basin of Tanzania.Victoria basin of Tanzania.

Synonyms:Synonyms:--virus de la mosaique du Gombovirus de la mosaique du Gombo..

Acronym :Acronym :--

OkMVOkMV


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Virus identificationVirus identification

The samples were tested by doubleThe samples were tested by double--antibodyantibody--

sandwich enzymesandwich enzyme--linked immunosorbent assaylinked immunosorbent assay

(DAS ELISA) using antiserum specific for(DAS ELISA) using antiserum specific for

OMV essentially as described by [OMV essentially as described by [Clark andClark and

Adams, 1977Adams, 1977].].

The remaining 3% reacted negatively to the

antiserum by producing no visible colour

development.


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Virion PropertiesVirion Properties::--

1)1) Virions consist of a capsid.Virions consist of a capsid.

2)2) Virus capsid is not envelopedVirus capsid is not enveloped

3)3) Round with icosahedral symmetry.Round with icosahedral symmetry.

4)4) The isometric capsid has a diameter of 28 nm.The isometric capsid has a diameter of 28 nm.

5)5) Capsids appear round.Capsids appear round.

6)6) The capsomer arrangement is clearly visible.The capsomer arrangement is clearly visible.

Nucleic Acid:Nucleic Acid:-- Only one particle size of linear, singleOnly one particle size of linear, single--strandedstranded

RNA is recovered.RNA is recovered.


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Proteins:Proteins:--

Proteins constitute about 68% of the particle weight.Proteins constitute about 68% of the particle weight.

The viral genome encodes structural proteins andThe viral genome encodes structural proteins andnonnon--structural proteins.structural proteins.

Lipids:Lipids:-- Lipids are not reported.Lipids are not reported.

Transmission and Vector Relationships:Transmission and Vector Relationships:--Virus is transmitted by a vector. Virus is transmittedVirus is transmitted by a vector. Virus is transmitted

by mechanical inoculation; transmitted by grafting; notby mechanical inoculation; transmitted by grafting; nottransmitted by seeds.transmitted by seeds.


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Natural host range:Natural host range:--..

1)1) HibiscusHibiscus sppspp

2)2) AbelmoscosAbelmoscos esculentusesculentus

3)3)Abutilon hirtumAbutilon hirtum

4)4)Adansonia digitataAdansonia digitata

5)5)Apium graveolensApium graveolens

6)6)Amaranthus retroflexusAmaranthus retroflexus

7)7) ChenopodiumChenopodium amaranticoloramaranticolor

8)8) Cucumis sativusCucumis sativus

9)9) Vigna unguiculataVigna unguiculata


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SYMPTOMSYMPTOM

VeinVein clearing followed by veinal chlorosis ofclearing followed by veinal chlorosis ofleavesleaves

The yellow network of vein is veryThe yellow network of vein is very

conspicuous and vein and veinlets areconspicuous and vein and veinlets arethickened.thickened.

All the infected plants had height of betweenAll the infected plants had height of between

10 and 40 cm.10 and 40 cm. Infected plants remain stunted and bear veryInfected plants remain stunted and bear very

few deformed and small fruits.few deformed and small fruits.


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Leaves of the diseased plants had diffuse mosaicLeaves of the diseased plants had diffuse mosaic

appearance .appearance .

veinal mottling and vein banding.veinal mottling and vein banding.

severely affected plants appeared stunted asseverely affected plants appeared stunted as

compared to the healthy ones.compared to the healthy ones.

Diseased plants showed reduction of19.5% inDiseased plants showed reduction of19.5% in

plant height, 34.7% in number of fruits per plantplant height, 34.7% in number of fruits per plant

and 32.1% in leaf petiole lengthand 32.1% in leaf petiole length


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The lowest reduction (11.3%) was in fruit length.The lowest reduction (11.3%) was in fruit length.

No flower was observed at the time of thisNo flower was observed at the time of thisassessment in all the fields.assessment in all the fields.

stem girth was 27% larger in diseased asstem girth was 27% larger in diseased ascompared to the healthy plants.compared to the healthy plants.

In the diseased plants fruits per plant ranged fromIn the diseased plants fruits per plant ranged from

zero to 9.zero to 9.

Leaf width ranged from 4.5 to 24 cm in diseasedLeaf width ranged from 4.5 to 24 cm in diseased

and 18.0and 18.035 cm in healthy plants35 cm in healthy plants


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Twisted leaves with reduced sizeTwisted leaves with reduced size..

In extreme cases, the infected leavesIn extreme cases, the infected leaves

become totally yellow or cream colour.become totally yellow or cream colour.

The disease causes heavy loss in yield if theThe disease causes heavy loss in yield if the

plants get infected within 20 days afterplants get infected within 20 days after

germination.germination.

Most of infected plants expressed downwardMost of infected plants expressed downward

curling of older leavescurling of older leaves


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Transmission:Transmission:--

Virus is not sap transmiable but it transmiable throughVirus is not sap transmiable but it transmiable through

the agency of white flies.the agency of white flies.

Transmitted byTransmitted byAphis gossypiiAphis gossypiioror BemisiaBemisia tabacitabaci

vectors.vectors.

Not seedNot seed--borne in okra .borne in okra .


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Healthy InfectedHealthy Infected


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Disease incidence:Disease incidence:--

Virus disease infection proportions averaged 55% andVirus disease infection proportions averaged 55% and

ranged from 30 to 89%.ranged from 30 to 89%.


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Management and Control:Management and Control:--

1) The vector population and disease incidence can1) The vector population and disease incidence can

be reduced by application of 4 to 5 foliar sprays ofbe reduced by application of 4 to 5 foliar sprays ofeither Dimethoate (0.05%) or Metasystoxeither Dimethoate (0.05%) or Metasystox

(0.02%) or Monocrotophos (0.05%) , followed by(0.02%) or Monocrotophos (0.05%) , followed by

1 or 2 sprays of mineral oil (2%).1 or 2 sprays of mineral oil (2%).2)2) One soil application of Furadon @ 1.5 kg a.i./haOne soil application of Furadon @ 1.5 kg a.i./ha

at the time of sowing seeds is also recommended.at the time of sowing seeds is also recommended.

3) Infected plants must be removed from the field3) Infected plants must be removed from the field4). Some okra lines have been evolved at IIHR4). Some okra lines have been evolved at IIHR

Bangalore, which are completely resistant toBangalore, which are completely resistant to

yellowvein mosaic of okra.yellowvein mosaic of okra.


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TOLERANT VARIETY:TOLERANT VARIETY:--

Subz, Pari, Pahuja, IPSA OKRA 1,Subz, Pari, Pahuja, IPSA OKRA 1,

SLSL--4444

MODERATELY RESISTANT VARIETY:MODERATELY RESISTANT VARIETY:--

Safal,Safal,


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ReferencesReferences::--Atiri and Fayoyin, 1989.Atiri and Fayoyin, 1989. G.I. Atiri and G.A. Fayoyin,G.I. Atiri and G.A. Fayoyin,

Horizontal resistance to okra leaf curl virus in okraHorizontal resistance to okra leaf curl virus in okra

germplasm.germplasm.Ann. Appl. Biol.Ann. Appl. Biol. 144144 (1989), pp. 152(1989), pp. 152153.153.

www.forestryimages.orgwww.forestryimages.orgVirus and Mycoplasma disease of plants in India :Virus and Mycoplasma disease of plants in India :--

By S.P. RaychaudhuriBy S.P. Raychaudhuri

T.K. NarianiT.K. Nariani


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yvm of okra

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