Presentation on theme: "Plant Virus Diseases in Nepal: Current Status and Future Strategies"— Presentation transcript:
1Plant Virus Diseases in Nepal: Current Status and Future Strategies Dr. RD. Timila , S. Joshi and Dr. BN. MahtoPlant Pathology Division,Nepal Agriculture Research Institute,Nepal Agricultural Research CouncilKhumaltar
2Contents Background Information Economic Significance Prevalent plant virus diseases in Nepal and their distributionCurrent status of major virus diseases in vegetable cropsSeed-borne virus diseases of vegetable cropsDiagnostic MethodologiesConstraintsFuture Strategies and Needs
3IntroductionCultivation of various vegetables is one of the most potential income generating sources for the livelihood of the majority of the farmersHigh value cropsVegetable cultivation:Area under = hProduction = mtProductivity= mt/h(Source: Vegetable Development Directorate, Annual Report, 2011/12)
4Diseases are one of the major constraints of successful cultivation Epidemic of some of the diseases are causing havoc with negative impact on the economy of the farmersIn recent years, viral disease problem appearing as the most important diseases for some of the major vegetable crops.
5It induces broad range of symptoms affecting growth, yield and quality of the produce Its incidence and severity is increasingNew virus like diseases are also emergingResearch and studies on plant viruses are limited in Nepal
6Economic Significance . Crop loss estimated 15-20% due to disease alone (Rajbhandary and Shrestha, 1992)In recent years, ‘virus diseases‘ caused significant Yield lossesPosed a threat for production and productivity of important crop plants especially vegetablesDeteriorate both quality and quantity of produce and ultimately reduces market price
7Its economic importance has been realized since past many years. Crop or yield losses incurred due to specific virus in specific crop in Nepal is not yet studied.However, some seed borne viruses could cause yield loss (Shrestha and Albrechtsen,1992) depending on type of virus and the crop.PSbMV in pea: up to 36%SBMV in cowpea: up to 59%CAMV in cowpea: up to 87%
8Prevalent plant virus diseases in Nepal and their distribution Cereals and Legumes:CropVirus diseaseDistribution/inc.RiceRice Tungro Virus, Rice dwarf VirusEastern & Central terai, KathMaizeMaize Leaf Fleck Mosaic VirusRampurWheatBarley Yellow Dwarf VirusBhairahawa (Terai)SoybeanSoybean Mosaic Virus, Tobacco Ring Spot Virus, Mungbean Yellow Mosaic VirusTerai and mid-hillsCowpeaCowpea Aphid-borne Mosaic Virus, Cowpea Mosaic VirusChitwan,Pea and Broad beanPea Seed- borne Mosaic Virus(in seed samples)
9Prevalent plant virus diseases in Nepal ………(contd.) Cereals and Legumes (contd.):CropVirus diseaseDistributionLentilPea Seed- borne Mosaic VirusMid-hills (In seed)Pigeon peaSterility Mosaic Virus, Yellow Mosaic VirusTerai and inner terai, (15-50% inc.)BlackgramBean Common Mosaic Virus(in seed)MungbeanMungbean Yellow Mosaic VirusTeraiGroundnutTomato Spotted Wilt Virus (Bud necrosis)
10Prevalent plant virus diseases in Nepal …….(Contd) Vegetables crops:CropVirus diseaseDistributionTomatoTomato Mosaic Virus, Tomato Leaf Curl Virus, Cucumber Mosaic VirusTerai, inner terai and mid-hillsPepper (Chili and capsicum)Tomato Leaf Curl Virus, Chili Veinal Mottle Virus, Cucumber Mosaic VirusCucumber and Zucchini squashCucumber Mosaic Virus, Zucchini Yellow Mosaic Virus, Watermelon Mosaic Virus 1 and 2, Squash Mosaic virus, Cucumber Green Mottle Mosaic VirusMid-hills, terai
11Prevalent plant virus diseases in Nepal …….(Contd) Vegetables crops:CropVirus diseaseDistributionBroad leaf mustard, Turnip, RadishTurnip Mosaic VirusMid-hillsOkraYellow Vein Mosaic VirusTerai, inner terai and mid-hillsBeanBean Common Mosaic Virus,Mid-hills,Y. Long beanSouthern Bean Mosaic VirusMid-hill and Terai
12Prevalent Plant virus diseases in Nepal…. (contd.) Fruits and cash crops:CropVirus diseaseDistributionPotatoPotato Leaf Roll Virus*, Potato Virus X, Potato Virus Y*, Potato Virus A, Potato Virus S, Potato Virus M*Terai, Mid-hills and high hillsLarge cardamomLarge Cardamom Chirkey Virus Chirkey), Cardamom Bushy Dwarf Virus (Foorkey)Ilam, Panchthar, Taplejung,CitrusCitrus Tristeza VirusMid-hills: Kaski, Dhankuta and DailekhPapayaPapaya Ring Spot VirusTerai, Inner terai and foot-hillsTobaccoTobacco Mosaic Virus, Tobacco Leaf Curl, Cucumber Mosaic Virus (Strain)Terai and inner terai
13Current status of major virus diseases in vegetable crops: TomatoTLCVFirst reported in 1994 (Timila and Joshi, 1994) after diagnosis using cDNA hybridization in collaboration with Dr. Maxwell (Univ. of Wisconsin) and AVRDC.The virus is distributed in terai, inner terai, valleys and foothills.
14Incidence ranged from40-70% (Joshi et al.1997) .Yield loss estimation in tomato was 50% (Joshi and Shrestha, 1999), 40% in Western hills (Ghimire et al., 2000).In recent years also, the disease is severe in western terai.Tomato mosaic virus (ToMV): Prevalent in tomato growing areas causing poor plant growth and also appeared in combination with other viruses.
15Cucumber mosaic virus (CMV): Widely distributed in tomato growing areas of the mid-hills. Observed to be major. Severely affected in some of the fields.CMV in TomatoCMV with other virus comlex
17Pepper:Virus complex varied from 30-90%. (joshi and Shrestha, 2001, AVRDC)TLCV: Distributed in terai, inner terai, valleys and foothills. Incidence ranged from 20-80% (Chilli) (Joshi et al.1997) .Chilli veinal mottle virus (CVMV): Higher Incidence and severity in pepper has been observed at Kathmandu valley (mid hills). Virus infected plants were more than 80% recorded (Shrestha and Albrechtsen, 1992). In recent years also, the disease status remaining the same.
18Cucumber mosaic Virus (CMV): Widely distributed in terai, inner terai and midhills. The incidence ranged from 50-80% (SAVERNET II, midterm report. 1999). Presently also the disease is problematic.
19Cucurbit:CMV in cucumber , distributed throughout cucumber cultivated areas of mid-hills in severe form as revealed by sample received at PPD, Khumaltar and as observed in the farmers’ fields, causing considerable losses (PPD, ).Complex infection of CMV, ZYMV, SqMV, WMV 1 and 2, and CGMMV in zucchini squash. Infection in some of the fields, up to 100% incidence at Kath. valley causing total crop failure (PPD, 2006).
20Various virus (Complex) disease symptoms in Zucchini squash Bottle gourd
21Broad leaf mustard:Turnip mosaic virus (TuMV): Observed mainly in broad leaf mustard but radish and turnip also affected. Widely distributed in the mid hills. Incidence up to 100%, causing total crop failure in some of the fields.
22Beans:Bean common mosaic virus (BCMV) has been observed in Bean fields in low incidence. Its distribution mainly in the mid-hills (as observed in the field visits)Bean common mosaic necrosis virus (BCMNV) recently reported from Kaski and Chitwan in Sweet bean with incidence ranging from 60-70% (Pudasaini et al., 2013).
23Okra:Mainly distributed in terai, inner terai and valleys of the mid hills. up to 70% incidence observed (Dahal, 1990). At present this disease is under high priority also.
24Potato: reported six viruses Potato leaf roll virus and potato virus y: distribution high in terai and moderate in midhills. They could cause yield loss 12-50% and 80% respectively.PVX, PVA, PVS and PVM, their distribution ranged from 24-27% higher in the Terai (24, 25, 27, 25%) but lesser than PLRV and PVY), Comparatively, PVX andPVS higher in high hills also.(Source, Dhital et al., 2010)
25Cardamom:Prevalence of Large cardamom chhirke virus (LCCV) and Cardamom bushy dwarf virus (CBDV) have been reported in the eastern hills with incidence ranging from 15-20% and 10% repectively (Srivastav, 2012). Low incidence of CBDV observed in our survey.(These viruses used to be the issues for cardamom crop, & losses not estimated yet)
26Some important identified seed-borne viruses in vegetable crops in Nepal Tomato mosaic virus (Tomato)Cucumber mosaic virus (Tomato, Pepper, Cucumber)Cucumber green mottle mosaic virus (Zucchini squash, Cucumber)Bean common mosaic virus (Common beans)Cowpea aphid borne mosaic virus (Cowpea)Southern bean mosaic virus (Yard- long bean)Pea seed-borne mosaic virus (Pea)Field tolerance limit of infected plants for BCMV has been fixed for seed production of bean crop Foundation seed: 0.1% and for certified seed: 0.2%
27Diagnostic Methodology adopted Growing on testIndicator host plant testSerological test (ELISA): based on the availability of antiserumcDNA hybridization test for TLCV: only during SAVERNET project period at AVRDC and Univ. of Wisconsin
28Previous Collaboration with International Intitutions Training, Technical back-up, Small Lab equipments and little suppliesDanish Seed Health Center for Developing Countries ( Previous DGISP)World Vegetable Center (AVRDC)ICRISAT
29ConstraintsLack of adequate laboratory facilities for virological ResearchLack of controlled condition Green house facilityLack of trained and adequate manpowerLack of logistic facilities (Vehicle) for survey and monitoringInadequate availability of other lab suppliesLack of continuous power supplyLack of incentive
30Future StrategyRegular survey and surveillance of virus diseases in different crop plants through out Nepal.Detection and diagnosis of viruses in major vegetable cropsEpidemiological and yield loss studies on important virus diseases of crop plantsSeed transmission studies on seed-borne virus diseases of vegetable crops in particularHost resistance screeningAlternative management tools for Integrated management
31Felt Needs For smooth running of Plant virus Research: Establishment of molecular laboratory at plant Pathology Division, NARCEstablishment of controlled condition green house.Collaboration with International IntitutionsStrengthening existing green and screen housesAdequate Human resource for virus workCapacity enhancement :Training for personnel in detection, diagnosis, vector virus relationship and etcExposure visits for scientists/techniciansContinuous power supply.
32ConclusionPast and the present virus disease scenario indicated that the occurrence of several viruses on cucurbits, legumes and solanaceous vegetables and other crops in epidemic form in the country.Virus suspected diseases observed, yet to be confirmedEmphasis should be given in conducting research and studies on different aspects of virus diseases to develop management tools.