Phosphonate Balances Cost and Eco-Safety, Matching Conventional Fungicide Efficacy in Potato Late Blight Management, But with Agroecology-Specific Response

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cg.authorship.typesCGIAR and developing country institute
cg.contributor.affiliationInternational Potato Center
cg.contributor.affiliationHaramaya University
cg.contributor.affiliationUniversity of Nairobi
cg.contributor.donorFederal Ministry for Economic Cooperation and Development, Germany
cg.contributor.programAcceleratorBreeding for Tomorrow
cg.contributor.programAcceleratorSustainable Farming
cg.coverage.countryKenya
cg.coverage.iso3166-alpha2KE
cg.coverage.regionAfrica
cg.creator.identifierkalpana sharma: 0000-0002-4104-8671
cg.creator.identifierElly Atieno: 0000-0002-4354-1785
cg.creator.identifierShadrack Nyawade: 0000-0003-4113-3400
cg.creator.identifierElmar Schulte-Geldermann: 0000-0003-1784-4333
cg.howPublishedFormally Published
cg.identifier.doihttps://doi.org/10.1016/j.cropro.2025.107499
cg.isijournalISI Journal
cg.issn1873-6904
cg.journalCrop Protection
cg.number107499
cg.reviewStatusPeer Review
cg.subject.actionAreaSystems Transformation
cg.subject.cipPOTATO AGRI-FOOD SYSTEMS
cg.subject.cipPOTATOES
cg.subject.cipCROP PROTECTION
cg.subject.cipCLIMATE CHANGE
cg.subject.cipIMPACT ASSESSMENT
cg.subject.impactAreaNutrition, health and food security
cg.subject.sdgSDG 3 - Good health and well-being
cg.subject.sdgSDG 4 - Quality education
cg.subject.sdgSDG 2 - Zero hunger
cg.volume202
dc.contributor.authorSharma, K.
dc.contributor.authorAtieno, E.
dc.contributor.authorNyawade, S.
dc.contributor.authorKumar, A.
dc.contributor.authorSchulte-Geldermann, Elmar
dc.date.accessioned2026-02-12T15:37:43Z
dc.date.available2026-02-12T15:37:43Z
dc.identifier.urihttps://hdl.handle.net/10568/181494
dc.titlePhosphonate Balances Cost and Eco-Safety, Matching Conventional Fungicide Efficacy in Potato Late Blight Management, But with Agroecology-Specific Responseen
dcterms.abstractPotato late blight caused by Phytophthora infestans imposes persistent yield and income losses in sub-Saharan Africa, requiring fungicide strategies tailored to agroecological and varietal contexts. This study assessed the efficacy, profitability, and environmental toxicity of three fungicides-metalaxyl-M + mancozeb (Ridomil Gold MZ (R)), mono- and di-potassium phosphite (phosphonate), and ametoctradin + dimethomorph (Orvego (R)). Metalaxyl-M + mancozeb (Metalaxyl-M + mancozeb) served as the commercial standard, with a no-spray control included as a baseline. Trials were conducted in Kenyan highland (>2100 m a.s.l.) and midland (1800-2000 m a.s.l.) zones, using 19 potato cultivars classified by susceptibility as Susceptible, Moderate, or Resistant. Fungicides were applied every 7 days, averaging 11 and 9 sprays per season at the highland and midland sites, respectively. Disease was quantified using the relative area under the disease progress curve (rAUDPC), environmental toxicity using the Environmental Impact Quotient (EIQ), and profitability through net returns and benefit-cost ratios (BCRs). Ametoctradin + dimethomorph achieved the greatest rAUDPC reduction over no spray (-0.738), followed by metalaxyl-M + mancozeb (-0.598) and phosphonate (-0.491). Compared to metalaxyl-M + mancozeb, ametoctradin + dimethomorph was more effective (-0.140), while phosphonate showed near-identical efficacy (+0.001). Yield gains over no spray were +24.4 t/ha with ametoctradin + dimethomorph, +20.7 t/ha with phosphonate, and +17.8 t/ha with metalaxyl-M + mancozeb. Against commercial standard, ametoctradin + dimethomorph yielded a significant +7.1 t/ha gain, but a non-significant yield loss (-1.1 t/ha) with phosphonate. Net returns ranged from USD 7950-9500/ha (ametoctradin + dimethomorph), 6100-8600/ha (phosphonate), and 5500-8000/ha (metalaxyl-M + mancozeb), with BCRs of 19.8-20.8, 12.7-13.7, and 9.2-10.2. Phosphonate had the lowest environmental impact (150-183 EIQ/ha), cutting toxicity by 253-310 units relative to metalaxyl-M + mancozeb and 156-127 compared to ametoctradin + dimethomorph. Phosphonate showed a zone-specific response relative to metalaxyl-M + mancozeb, with reduced efficacy in the Highland (-14.76 %, p = 0.0071) and increased efficacy in the Midland (+12.91 %, p = 0.0282). These findings position phosphonate as a cost-effective, eco-safer option and ametoctradin + dimethomorph as more effective but costlier, with a moderate environmental impact. The zone-specific performance of phosphonate highlights trade-offs in its effectiveness and suitability across locations, shaping both farmer and policy decisions.en
dcterms.accessRightsLimited Access
dcterms.audienceAcademics
dcterms.audienceCGIAR
dcterms.audienceDevelopment Practitioners
dcterms.audienceDonors
dcterms.audienceExtension
dcterms.audienceFarmers
dcterms.audienceGeneral Public
dcterms.audienceNGOs
dcterms.audiencePolicy Makers
dcterms.audienceScientists
dcterms.available2025-12
dcterms.bibliographicCitationSharma, K.; Atieno, E.; Nyawade, S.; Kumar, A.; Schulte-Geldermann, E. 2025. Phosphonate balances cost and eco-safety, matching conventional fungicide efficacy in potato late blight management, but with agroecology-specific response. Crop Protection. ISSN 1873-6904. 202, 107499. https://doi.org/10.1016/j.cropro.2025.107499
dcterms.issued2026-04
dcterms.languageen
dcterms.licenseCopyrighted; all rights reserved
dcterms.publisherElsevier
dcterms.subjectphytophthora infestans
dcterms.subjectfungicides
dcterms.subjectenvironmental impact
dcterms.subjectintegrated pest management
dcterms.typeJournal Article

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