4.2 Disease Control and Pest Management in Cassava Production by Kumar, IITA

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Transcript of 4.2 Disease Control and Pest Management in Cassava Production by Kumar, IITA

  • Disease Control and Pest Management in Cassava ProductionLava Kumar, R. Hanna, P. Kulakow, J. Legg, E. Kanju, P. Ntuhunguru and N. Mahungu

  • IntroductionNeed for cassava intensificationTo meet the demands of increasing population growthIncrease in demand for alternative uses - bioenergy

    Way forwardIncrease in yields in the same unit area in traditional growing areasCultivation in new niches

    ChallengesPoor adoption of improved varieties and crop management practices.

    Threats from established and emerging pests and diseases in traditional and new cassava niches.

    Climate change effect on host, pathogens and pests.

    Lack of enabling environment (inadequate financial, policy and political support)

  • Cassava productivity

    EA = 8.8 MtCA =8.9 mtNA=1.6 MtWA=11.5 mtCA=11.9 mtSA=13.5 mtSA=32.5 mtEA=16.6 mtSEA=19.3 mtLatin AmericaTraditional cultivationPests and diseases

    AsiaAdoption of improved varieties and technologies from the outsetLow pests and diseases

    AfricaSubsistence agriculturePoor adoption of improved varieties Diseases (CMD & CBSD) and pests

  • GenotypeEnvironmentManagementBiotic stressesAbiotic stressesGEM factor on cassava yieldPestsDiseasesPlanting material

  • Exotic pestsGreen spider mite (Mononychellus tanajoa) Cassava mealy bug, (Phenacoccus manihoti) Cassava Bacterial Blight (Xanthomonas axonopodis) Indian cassava mosaic virus

    Pests of regional importance Cassava brown streak virus East African cassava mosaic virus Uganda (EACMV-UG)

    Cassava pests in AfricaIndigenous pestsAfrican cassava mosaic virusEast African cassava mosaic virus complexSouth African cassava mosaic virusWhiteflies, fungal diseases, root scales etc

  • Pests not present in the continent Cassava common mosaic virusCassava green mosaic virus Cassava vein virus Cassava X virusFrog Skin Disease Cassava antholysis Cassava witches broomSuper Elongation (Sphaceloma manihoticola)

    Quarantine pests of cassava in Africa

  • Cassava die-back caused by Collectotricum gloeosporioides

    Leaf spots caused by Collectotricum gloeosporioides

  • Cassava bacterial blight (CBB) Xanthomonas axonopodis pv manihotis Leaf spots caused by Cercospora caribea

  • Brown leaf spot Cercospora henigsii

    Super Elongation (Sphaceloma manihoticola- Elsinoe brasilensis)


  • Severe mottling and leaf distortion on indicator clone Secundina grafted on infected stake (leaves from buds on rootstock show no symptoms) Source: Dr L.A. Calvert, CIATFrog skin disease (FSD)

  • Cassava green mite (Mononychellus tanajoa)Predatory mite -- Typhlodromalus aripo feeds on cassava green miteIntroduced to Africa from Brazil in 1993 for biological control of cassava green mite Mononychellus tanajoa

    and biocontrol

  • Whitefly (Bemisica tabaci)Pest and important virus vectorSooty mould

  • The viruses of cassava in AfricaAfrican cassava mosaic virus (ACMV) Indian cassava mosaic virus

    East African cassava mosaic virus (EACMV)South African cassava mosaic virus (SACMV) East African cassava mosaic Cameroon virus East African cassava mosaic Malawi virusEast African cassava mosaic Zanzibar virus East African cassava mosaic Kenya virus EACMV-Uganda (recombinant virus)

    Cassava brown streak virus (Ipomovirus)Cassava brown streak Uganda virus

    Cassava Ivorian bacilliform virus* Cassava Kumi virus*Cassava Q virus*Cassava common mosaic virus* (Potexvirus)CMGsCBSV



  • Movement of CMBVs in SSASource: Ndunguru et al. 2005

  • Viruses cannot move, they are movedThey move with host (propagation material)

    They are transmitted by vectors

    Cassava virus spreadWhitefliesStem cuttingsIn vitro cultures

  • CMG Distribution - 2004

  • CMG DistributionIncrease in incidence of mixed infections in West Central Africa

  • Tracking the spread of EACMV-UGAs of 2005, Spread in 2.6 million sq. km causing an estimated loss of 47% in affected countries.

  • Farmer yields of improved and local varieties by state in SS and SE Nigeria

  • Cassava Mosaic Disease SeverityYear of cloningMean log(CMD severity)Genetic gain/year = 0.44%

  • *Better management of cassava mosaic diseaseAdditional production of 11.4 million tonsAdditional value of US$ 798.6 millions

    Production (Million Mt)Value (million US$)15% increase*(million Mt)Additional value (million US$)Nigeria45.723200.56.86480.1DRC14.971048.22.25157.2Ghana9.64674.71.45101.2Benin2.52176.70.3826.5Ivory Coast2.20154.00.3323.1Total76.065324.011.41798.61

  • Cassava brown streak virusFirst recognized in 1920s.Occurs in Kenya, Uganda, Tanzania, Malawi and Mozambique.Suspected in DRC, Congo, Burundi and Rwanda. Evidence of westward spread

  • Cassava brown streak disease

  • C3P ProjectReports prior to 2004 (since 1920s)CBSD distributionTracking CBSD distribution and spread

    Since 2008, its occurrence in Rwanda, Burundi and Eastern DRC confirmed.

  • CBSDCBSD disguise ready detection

  • Near normal tubers, but server damage to root quality

  • CBSVCBSUVTwo viruses

  • Difficult to diagnose CBSD

  • Cassava brown streak disease

  • Simple diagnostics developed at IITA for simultaneous diagnosis of CMD and CBSD

  • USAID project

  • CBSD management Cultivation of tolerant varietiesClean planting material

    CBSD is a serious threat to cassava worldwide. Consorted efforts are required to pre-emptive management of CBSD

  • Spiraling whitefly (Aleurodicus dispersus) Watch-out for new pests

  • Cassava mealybug (Phenococcus manihoti) well established in Latin America and SSA.

    New outbreak in 200,000 ha in Thai Land

    (CIAT Alert, 2010)

    Threat to other Asian countries.

    Watch-out for new outbreaksAnagyrus lopezi Biological control using natural enemy, a wasp, A. lopezi.

  • Cassava bacterial blight in Vietnam.

    New Phytoplasma disease in South-East Asia

    Watch-out for new outbreaks

  • Training in field surveillance and laboratory diagnosis

    Training & capacity building

  • Awareness creation

  • Planting materialTubersStarchEthanolQuality planting material is fundamental to increase cassava productivityQuality planting material to manage biotic threats

  • Challenges due to clonal propagationVery low multiplication ratio (1:8), bulky & Perishable

    Multiplication and distribution of stems are more expensive than conventional seed (grain based)

    Farmers do not specifically multiply stems for propagation, but use stems from harvested plants.

    Lack of incentive for the private sector to invest, and lack of markets (due to low affordability by farmers)



  • Challenges due to clonal propagation (2)Spread of pathogens particularly viruses (introduction and perpetuation)



  • Few actors involved in cassava stem multiplication Private non-profit organizations (e.g. NGOs, foundations);Public institutions (e.g. extension services, research institutions)Community organizations (CBOs)

    Depends on donor investmentsLack of sustainabilityCultural issues sometimes affect multiplication projects

    Weak seed sector, Expansion of area (intensification)

    High demand for planting materialShort supply of planting material


  • Massive multiplication & exchange programs Demand met through massive multiplication projectsMassive movement of planting material within & between countries

    Inherent risk of pathogen exchange through planting material

    Particular problem with viruses

    - Cassava mosaic disease - Cassava brown streak diseasePlanting material could carry pathogens harmful pests and pathogens.


  • Knowledge on pathogens and their distributionEssential needs for germplasm monitoring Availability of diagnostic toolsCapacity (human skills and infrastructure)Guidelines: FAO, IPPC, IAPSC, NPPO

  • Production of clean planting materialMaterial from the field:Insects NematodesFungiBacteria Viruses

    Elimination of pests and pathogens through tissue culture, but not viruses.

  • Scheme for CBSD-free planting material

    VarietyNo. of testedNumber CBSV-free1MM06/001120TC15 2MM06/002420TC10 3MM06/013820TC3 4MM06/013120TC3 5MM06/001920TC9 6MM06/007920TC11 7MM06/001320TC1 8MM06/004520TC20 9MM06/001220TC20 10MM06/0023B20TC8 11MM06/013920TC2 12MM06/012420TC4 13MM06/011220TC3 14MM06/007620TC6

  • Provide adequate supply of cassava products at economically affordable prices through availability of improved cassava varieties, production processes and farm gate processing in seven countries.

    Together with national programs and CSOs

    Unleashing the Power of Cassava in Africa UPoCA(USDA project in response to food crisis)

  • To distribute clean planting material to 1.15 million ho