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Nyirakanani C, Tamisier L, Bizimana JP, Rollin J, Nduwumuremyi A, Bigirimana VDP, Selmi I, Lasois L, Vanderschuren H, Massart S. Going beyond consensus genome sequences: An innovative SNP-based methodology reconstructs different Ugandan cassava brown streak virus haplotypes at a nationwide scale in Rwanda. Virus Evol 2023; 9:vead053. [PMID: 37692897 PMCID: PMC10491861 DOI: 10.1093/ve/vead053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/14/2023] [Accepted: 08/20/2023] [Indexed: 09/12/2023] Open
Abstract
Cassava Brown Streak Disease (CBSD), which is caused by cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), represents one of the most devastating threats to cassava production in Africa, including in Rwanda where a dramatic epidemic in 2014 dropped cassava yield from 3.3 million to 900,000 tonnes (1). Studying viral genetic diversity at the genome level is essential in disease management, as it can provide valuable information on the origin and dynamics of epidemic events. To fill the current lack of genome-based diversity studies of UCBSV, we performed a nationwide survey of cassava ipomovirus genomic sequences in Rwanda by high-throughput sequencing (HTS) of pools of plants sampled from 130 cassava fields in thirteen cassava-producing districts, spanning seven agro-ecological zones with contrasting climatic conditions and different cassava cultivars. HTS allowed the assembly of a nearly complete consensus genome of UCBSV in twelve districts. The phylogenetic analysis revealed high homology between UCBSV genome sequences, with a maximum of 0.8 per cent divergence between genomes at the nucleotide level. An in-depth investigation based on Single Nucleotide Polymorphisms (SNPs) was conducted to explore the genome diversity beyond the consensus sequences. First, to ensure the validity of the result, a panel of SNPs was confirmed by independent reverse transcription polymerase chain reaction (RT-PCR) and Sanger sequencing. Furthermore, the combination of fixation index (FST) calculation and Principal Component Analysis (PCA) based on SNP patterns identified three different UCBSV haplotypes geographically clustered. The haplotype 2 (H2) was restricted to the central regions, where the NAROCAS 1 cultivar is predominantly farmed. RT-PCR and Sanger sequencing of individual NAROCAS1 plants confirmed their association with H2. Haplotype 1 was widely spread, with a 100 per cent occurrence in the Eastern region, while Haplotype 3 was only found in the Western region. These haplotypes' associations with specific cultivars or regions would need further confirmation. Our results prove that a much more complex picture of genetic diversity can be deciphered beyond the consensus sequences, with practical implications on virus epidemiology, evolution, and disease management. Our methodology proposes a high-resolution analysis of genome diversity beyond the consensus between and within samples. It can be used at various scales, from individual plants to pooled samples of virus-infected plants. Our findings also showed how subtle genetic differences could be informative on the potential impact of agricultural practices, as the presence and frequency of a virus haplotype could be correlated with the dissemination and adoption of improved cultivars.
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Affiliation(s)
- Chantal Nyirakanani
- Plant Genetics and Rhizosphere Processes Laboratory, TERRA Teaching and Research Center, University of Liège, Gembloux Agro-Bio Tech, Gembloux 5030, Belgium
- Department of Crop Sciences, School of Agriculture and Food Sciences, College of Agriculture, Animal Sciences and Veterinary Medicine, University of Rwanda, Musanze 210, Rwanda
| | - Lucie Tamisier
- Integrated and Urban Plant Pathology Laboratory, TERRA Teaching and Research Center, University of Liège, Gembloux Agro-Bio Tech, Gembloux 5030, Belgium
| | - Jean Pierre Bizimana
- Plant Genetics and Rhizosphere Processes Laboratory, TERRA Teaching and Research Center, University of Liège, Gembloux Agro-Bio Tech, Gembloux 5030, Belgium
- Department of Research, Rwanda Agriculture and Animal Resources Development Board, Huye 5016, Rwanda
| | - Johan Rollin
- Integrated and Urban Plant Pathology Laboratory, TERRA Teaching and Research Center, University of Liège, Gembloux Agro-Bio Tech, Gembloux 5030, Belgium
- Department of Research, DNAVision, Gosselies, Charleroi 6041, Belgium
| | - Athanase Nduwumuremyi
- Department of Research, Rwanda Agriculture and Animal Resources Development Board, Huye 5016, Rwanda
| | - Vincent de Paul Bigirimana
- Department of Crop Sciences, School of Agriculture and Food Sciences, College of Agriculture, Animal Sciences and Veterinary Medicine, University of Rwanda, Musanze 210, Rwanda
| | - Ilhem Selmi
- Integrated and Urban Plant Pathology Laboratory, TERRA Teaching and Research Center, University of Liège, Gembloux Agro-Bio Tech, Gembloux 5030, Belgium
| | - Ludivine Lasois
- Plant Genetics and Rhizosphere Processes Laboratory, TERRA Teaching and Research Center, University of Liège, Gembloux Agro-Bio Tech, Gembloux 5030, Belgium
| | - Hervé Vanderschuren
- Plant Genetics and Rhizosphere Processes Laboratory, TERRA Teaching and Research Center, University of Liège, Gembloux Agro-Bio Tech, Gembloux 5030, Belgium
- Tropical Crop Improvement Laboratory, Department of Biosystems, Katholieke Universiteit Leuven, Heverlee, Leuven 3001, Belgium
| | - Sébastien Massart
- Integrated and Urban Plant Pathology Laboratory, TERRA Teaching and Research Center, University of Liège, Gembloux Agro-Bio Tech, Gembloux 5030, Belgium
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Godding D, Stutt ROJH, Alicai T, Abidrabo P, Okao-Okuja G, Gilligan CA. Developing a predictive model for an emerging epidemic on cassava in sub-Saharan Africa. Sci Rep 2023; 13:12603. [PMID: 37537204 PMCID: PMC10400665 DOI: 10.1038/s41598-023-38819-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 07/15/2023] [Indexed: 08/05/2023] Open
Abstract
The agricultural productivity of smallholder farmers in sub-Saharan Africa (SSA) is severely constrained by pests and pathogens, impacting economic stability and food security. An epidemic of cassava brown streak disease, causing significant yield loss, is spreading rapidly from Uganda into surrounding countries. Based on sparse surveillance data, the epidemic front is reported to be as far west as central DRC, the world's highest per capita consumer, and as far south as Zambia. Future spread threatens production in West Africa including Nigeria, the world's largest producer of cassava. Using innovative methods we develop, parameterise and validate a landscape-scale, stochastic epidemic model capturing the spread of the disease throughout Uganda. The model incorporates real-world management interventions and can be readily extended to make predictions for all 32 major cassava producing countries of SSA, with relevant data, and lays the foundations for a tool capable of informing policy decisions at a national and regional scale.
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Affiliation(s)
- David Godding
- Epidemiology and Modelling Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK.
| | - Richard O J H Stutt
- Epidemiology and Modelling Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Titus Alicai
- National Crops Resources Research Institute, P. O. Box 7084, Kampala, Uganda
| | - Phillip Abidrabo
- National Crops Resources Research Institute, P. O. Box 7084, Kampala, Uganda
| | - Geoffrey Okao-Okuja
- National Crops Resources Research Institute, P. O. Box 7084, Kampala, Uganda
| | - Christopher A Gilligan
- Epidemiology and Modelling Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
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Chikoti PC, Tembo M. Expansion and impact of cassava brown streak and cassava mosaic diseases in Africa: A review. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2022. [DOI: 10.3389/fsufs.2022.1076364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Africa produces over half of global cassava; however, the continent's average yield is below the potential yields achieved under experimental conditions. Many factors contributing to low yield include lack of quality varieties, poor soils, limited access to capital, competition for labor, as well as pests and diseases. Plant diseases are the major biotic constraints to cassava production and have caused considerable food insecurity in Africa. Although there has been some level of disease management which has contributed to the increase in cassava production, the two viral diseases: cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) still claim between 30–40% and upto 70%, respectively of Africa's cassava harvest. Given the importance of the two diseases in Africa, we review the expansion of CBSD and CMD; impacts of the two diseases on food security and how they can be managed. We provide insights in the spread of the two diseases, management efforts, and future directions.
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Shirima RR, Wosula EN, Hamza AA, Mohammed NA, Mouigni H, Nouhou S, Mchinda NM, Ceasar G, Amour M, Njukwe E, Legg JP. Epidemiological Analysis of Cassava Mosaic and Brown Streak Diseases, and Bemisia tabaci in the Comoros Islands. Viruses 2022; 14:v14102165. [PMID: 36298720 PMCID: PMC9608219 DOI: 10.3390/v14102165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/15/2022] [Accepted: 09/28/2022] [Indexed: 01/20/2023] Open
Abstract
A comprehensive assessment of cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) was carried out in Comoros where cassava yield (5.7 t/ha) is significantly below the African average (8.6 t/ha) largely due to virus diseases. Observations from 66 sites across the Comoros Islands of Mwali, Ngazidja, and Ndzwani revealed that 83.3% of cassava fields had foliar symptoms of CBSD compared with 95.5% for CMD. Molecular diagnostics confirmed the presence of both cassava brown streak ipomoviruses (CBSIs) and cassava mosaic begomoviruses (CMBs). Although real-time RT-PCR only detected the presence of one CBSI species (Cassava brown streak virus, CBSV) the second species (Ugandan cassava brown streak virus, UCBSV) was identified using next-generation high-throughput sequencing. Both PCR and HTS detected the presence of East African cassava mosaic virus (EACMV). African cassava mosaic virus was not detected in any of the samples. Four whitefly species were identified from a sample of 131 specimens: Bemisia tabaci, B. afer, Aleurodicus dispersus, and Paraleyrodes bondari. Cassava B. tabaci comprised two mitotypes: SSA1-SG2 (89%) and SSA1-SG3 (11%). KASP SNP genotyping categorized 82% of cassava B. tabaci as haplogroup SSA-ESA. This knowledge will provide an important base for developing and deploying effective management strategies for cassava viruses and their vectors.
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Affiliation(s)
- Rudolph Rufini Shirima
- International Institute of Tropical Agriculture (IITA-Tanzania), P.O. Box 34441, Dar es Salaam 14112, Tanzania
- Correspondence: ; Tel.: +25-52-2270-0092
| | - Everlyne Nafula Wosula
- International Institute of Tropical Agriculture (IITA-Tanzania), P.O. Box 34441, Dar es Salaam 14112, Tanzania
| | - Abdou Azali Hamza
- Institut National de Recherche pour L’Agriculture, La Pêche et L’Environnement (INRAPE), Moroni BP 1406, Comoros
| | - Nobataine Ali Mohammed
- Institut National de Recherche pour L’Agriculture, La Pêche et L’Environnement (INRAPE), Moroni BP 1406, Comoros
| | - Hadji Mouigni
- Institut National de Recherche pour L’Agriculture, La Pêche et L’Environnement (INRAPE), Moroni BP 1406, Comoros
| | - Salima Nouhou
- Institut National de Recherche pour L’Agriculture, La Pêche et L’Environnement (INRAPE), Moroni BP 1406, Comoros
| | - Naima Mmadi Mchinda
- Institut National de Recherche pour L’Agriculture, La Pêche et L’Environnement (INRAPE), Moroni BP 1406, Comoros
| | - Gloria Ceasar
- International Institute of Tropical Agriculture (IITA-Tanzania), P.O. Box 34441, Dar es Salaam 14112, Tanzania
| | - Massoud Amour
- International Institute of Tropical Agriculture (IITA-Tanzania), P.O. Box 34441, Dar es Salaam 14112, Tanzania
| | - Emmanuel Njukwe
- West and Central African Council for Agricultural Research and Development (CORAF), Dakar CP 18523, Senegal
| | - James Peter Legg
- International Institute of Tropical Agriculture (IITA-Tanzania), P.O. Box 34441, Dar es Salaam 14112, Tanzania
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Casinga CM, Wosula EN, Sikirou M, Shirima RR, Munyerenkana CM, Nabahungu LN, Bashizi BK, Ugentho H, Monde G, Legg JP. Diversity and Distribution of Whiteflies Colonizing Cassava in Eastern Democratic Republic of Congo. INSECTS 2022; 13:849. [PMID: 36135550 PMCID: PMC9504715 DOI: 10.3390/insects13090849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 08/31/2022] [Indexed: 06/16/2023]
Abstract
The present study characterizes Bemisia tabaci and Bemisia afer from cassava in eastern Democratic Republic of Congo (DRC). The Mitochondrial COI sequencing revealed the occurrence of six cassava B. tabaci mitotypes, which were designated into four haplogroups (SSA-ECA, SSA-CA, SSA2, and SSA-ESA) using KASP SNP genotyping. SSA-ECA (72%) was the most prevalent and occurred in the northern part of the surveyed area, in the Ituri and Nord/Sud-Kivu provinces, whilst SSA-CA (21%) was present in the south, primarily in Haut-Katanga. SSA-ECA was predominant in the areas of north-eastern DRC most severely affected by cassava brown streak disease and was also reported in the new outbreak area in Pweto territory, Haut-Katanga, in the south. Bemisia afer comprised two major clusters with 85.5% of samples in cluster one, while the rest were in cluster two, which has no reference sequence in GenBank. This study provides important information on the genetic diversity of B. tabaci and B. afer in eastern DRC. This knowledge will be used as a basis for further studies to understand and to identify the role of whitefly haplogroups, their population densities and consequences for virus epidemics and spread as well as leading to improved vector and virus management strategies.
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Affiliation(s)
- Clérisse M. Casinga
- International Institute of Tropical Agriculture, Bukavu-Kalambo, Bukavu, Democratic Republic of the Congo
- Department of Environmental Sciences, Université du Cinquantenaire de Lwiro, Kabare, Bukavu, Democratic Republic of the Congo
| | - Everlyne N. Wosula
- International Institute of Tropical Agriculture, Dar es Salaam, Tanzania
| | - Mouritala Sikirou
- International Institute of Tropical Agriculture, Kinshasa, Democratic Republic of the Congo
| | - Rudolph R. Shirima
- International Institute of Tropical Agriculture, Dar es Salaam, Tanzania
| | - Carine M. Munyerenkana
- International Institute of Tropical Agriculture, Bukavu-Kalambo, Bukavu, Democratic Republic of the Congo
| | - Leon N. Nabahungu
- International Institute of Tropical Agriculture, Bukavu-Kalambo, Bukavu, Democratic Republic of the Congo
| | - Benoit K. Bashizi
- International Institute of Tropical Agriculture, Bukavu-Kalambo, Bukavu, Democratic Republic of the Congo
| | - Henry Ugentho
- Programme National Manioc, Institut National d’Etude et de Recherche Agronomiques de Mulungu, Bukavu-Mulungu, Democratic Republic of the Congo
| | - Godefroid Monde
- Department of Plant Virology, Institut Facultaire des Sciences Agronomiques, Kisangani-Yangambi, Kisangani, Democratic Republic of the Congo
| | - James P. Legg
- International Institute of Tropical Agriculture, Dar es Salaam, Tanzania
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Gaba S, Varma A, Prasad R, Goel A. Exploring the Impact of Bioformulated Copper Oxide Nanoparticles on Cytomorphology of Alternaria brassicicola. Curr Microbiol 2022; 79:244. [PMID: 35796840 DOI: 10.1007/s00284-022-02927-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/07/2022] [Indexed: 11/03/2022]
Abstract
Black leaf spot of Brassica species is caused by a foliar pathogen Alternaria brassicicola (A. brassicicola), the noxious killer of mustard, cabbage, and cauliflower crops. The current investigation involved the synthesis of copper oxide nanoparticles (CuO NPs) from potential strain of Trichoderma harzianum (T. harzianum). Characterization of CuO NPs was performed by UV-vis, FTIR, XRD, SEM-EDX, and HR-TEM studies. UV-visible spectra showed an absorption peak at 275 nm. FTIR study revealed the presence of N-H bonds which could be due to the presence of enzymes and secondary metabolites released in the filtrate of T. harzianum. SEM and HR-TEM revealed the cube shape CuO NPs formed and average particle size was in the range of 31-45 nm. Poisoned food technique was used to check the antifungal efficacy of CuO NPs against A. brassicicola at various concentrations (0.025, 0.050, 0.1, and 0.15 mg/mL). In vitro assays carried on potato dextrose agar showed maximum antifungal activity at 0.15 mg/mL. The control sample have cylindrical and oblong shape conidia, while transverse septation was 2-4 in untreated population. The lower concentrations of CuO NPs (0.025 and 0.050 mg/mL) caused malformed spherical shape conidia with excessive septation, while its higher concentrations (0.1 and 0.15 mg/mL) leads to viability loss in fungal culture. Results indicated that a higher concentration of CuO NPs serve as an effective biocidal concentration for the control of phytopathogens.
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Affiliation(s)
- Swati Gaba
- Amity Institute of Microbial Technology, Amity University, Noida, 201303, India
| | - Ajit Varma
- Amity Institute of Microbial Technology, Amity University, Noida, 201303, India
| | - Ram Prasad
- Department of Botany, Mahatma Gandhi Central University, Motihari, Bihar, 845801, India.
| | - Arti Goel
- Amity Institute of Microbial Technology, Amity University, Noida, 201303, India.
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Amelework AB, Bairu MW. Advances in Genetic Analysis and Breeding of Cassava ( Manihot esculenta Crantz): A Review. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11121617. [PMID: 35736768 PMCID: PMC9228751 DOI: 10.3390/plants11121617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 05/30/2023]
Abstract
Cassava (Manihot esculenta Crantz) is the sixth most important food crop and consumed by 800 million people worldwide. In Africa, cassava is the second most important food crop after maize and Africa is the worlds' largest producer. Though cassava is not one of the main commodity crops in South Africa, it is becoming a popular crop among farming communities in frost-free areas, due to its climate-resilient nature. This necessitated the establishment of a multi-disciplinary research program at the Agricultural Research Council of South Africa. The objective of this review is to highlight progress made in cassava breeding and genetic analysis. This review highlights the progress of cassava research worldwide and discusses research findings on yield, quality, and adaptability traits in cassava. It also discusses the limitations and the prospects of the cassava R&D program towards development of the cassava industry in South Africa.
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Affiliation(s)
- Assefa B. Amelework
- Agricultural Research Council, Vegetable and Ornamental Plants, Private Bag X293, Pretoria 0001, South Africa;
| | - Michael W. Bairu
- Agricultural Research Council, Vegetable and Ornamental Plants, Private Bag X293, Pretoria 0001, South Africa;
- Faculty of Natural & Agricultural Sciences, School of Agricultural Sciences, Food Security and Safety Focus Area, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
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Nyirakanani C, Bizimana JP, Kwibuka Y, Nduwumuremyi A, Bigirimana VDP, Bucagu C, Lassois L, Malice E, Gengler N, Massart S, Bragard C, Habtu M, Brostaux Y, Thonar C, Vanderschuren H. Farmer and Field Survey in Cassava-Growing Districts of Rwanda Reveals Key Factors Associated With Cassava Brown Streak Disease Incidence and Cassava Productivity. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2021. [DOI: 10.3389/fsufs.2021.699655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cassava (Manihot esculenta Crantz) is a vital crop in Rwanda where it ranks as the third most consumed staple. However, cassava productivity remains below its yield potential due to several constraints, including important viral diseases, such as cassava brown streak disease (CBSD). Because various factors can be addressed to mitigate the impact of viral diseases, it is essential to identify routes of virus contamination in the cassava agrosystems from the seed system to farmer's practices and knowledge. The present study aimed at (1) assessing the current cassava seed system and farmers' practices and their knowledge of the biotic constraints to cassava production, (2) determining the status of CBSD as well as critical factors associated with its spread through the seed system channels, and (3) determining factors that influence cassava productivity in Rwanda. A cross-sectional study was carried out from May to September 2019 in 13 districts of Rwanda. A total of 130 farmers and cassava fields were visited, and the incidence and severity of CBSD were evaluated. CBSD was detected in all cassava-producing districts. The highest field incidence of CBSD was recorded in the Nyanza district (62%; 95% CI = 56–67%) followed by the Bugesera district (60%; 95% CI = 54–65%), which recorded the highest severity score of 3.0 ± 0.6. RT-PCR revealed the presence of CBSD at the rate of 35.3%. Ugandan cassava brown streak virus was predominant (21.5%) although cassava brown streak virus was 4% and mixed infection was 10%. An informal cassava seed system was dominant among individual farmers, whereas most cooperatives used quality seeds. Cassava production was found to be significantly influenced by the use of fertilizer, size of the land, farming system, cassava viral disease, and type of cassava varieties grown (p < 0.001). Disease management measures were practiced by a half of participants only. Factors found to be significantly associated with CBSD infection (p < 0.05) were the source of cuttings, proximity to borders, age of cassava, and knowledge of CBSD transmission and management.
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Szyniszewska AM, Chikoti PC, Tembo M, Mulenga R, Gilligan CA, van den Bosch F, McQuaid CF. Smallholder Cassava Planting Material Movement and Grower Behavior in Zambia: Implications for the Management of Cassava Virus Diseases. PHYTOPATHOLOGY 2021; 111:1952-1962. [PMID: 33856231 DOI: 10.1094/phyto-06-20-0215-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Cassava (Manihot esculenta) is an important food crop across sub-Saharan Africa, where production is severely inhibited by two viral diseases, cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), both propagated by a whitefly vector and via human-mediated movement of infected cassava stems. There is limited information on growers' behavior related to movement of planting material, as well as growers' perception and awareness of cassava diseases, despite the importance of these factors for disease control. This study surveyed a total of 96 cassava subsistence growers and their fields across five provinces in Zambia between 2015 and 2017 to address these knowledge gaps. CMD symptoms were observed in 81.6% of the fields, with an average incidence of 52% across the infected fields. No CBSD symptoms were observed. Most growers used planting materials from their own (94%) or nearby (<10 km) fields of family and friends, although several large transactions over longer distances (10 to 350 km) occurred with friends (15 transactions), markets (1), middlemen (5), and nongovernmental organizations (6). Information related to cassava diseases and certified clean (disease-free) seed reached only 48% of growers. The most frequent sources of information related to cassava diseases included nearby friends, family, and neighbors, while extension workers were the most highly preferred source of information. These data provide a benchmark on which to plan management approaches to controlling CMD and CBSD, which should include clean propagation material, increasing growers' awareness of the diseases, and increasing information provided to farmers (specifically disease symptom recognition and disease management options).[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
| | - Patrick Chiza Chikoti
- Zambia Agriculture Research Institute, Plant Protection and Quarantine Division, Mt. Makulu Research Station, Chilanga, Zambia
| | - Mathias Tembo
- Zambia Agriculture Research Institute, Plant Protection and Quarantine Division, Mt. Makulu Research Station, Chilanga, Zambia
| | - Rabson Mulenga
- Zambia Agriculture Research Institute, Plant Protection and Quarantine Division, Mt. Makulu Research Station, Chilanga, Zambia
| | | | - Frank van den Bosch
- Department of Environment & Agriculture, Centre for Crop and Disease Management, Curtin University, Bentley, Perth, WA 6102, Australia
| | - Christopher Finn McQuaid
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, WC1E 7HT London, United Kingdom
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Casinga CM, Shirima RR, Mahungu NM, Tata-Hangy W, Bashizi KB, Munyerenkana CM, Ughento H, Enene J, Sikirou M, Dhed'a B, Monde G, Kumar PL, Legg JP. Expansion of the Cassava Brown Streak Disease Epidemic in Eastern Democratic Republic of Congo. PLANT DISEASE 2021; 105:2177-2188. [PMID: 33258425 DOI: 10.1094/pdis-05-20-1135-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Cassava plays a key role in ensuring food security and generating income for smallholder farmers throughout Central Africa, particularly in the Democratic Republic of Congo (DRC). This status is threatened, however, by cassava brown streak disease (CBSD), which has expanded its incidence and range in eastern DRC. The study described here comprises the first extensive assessment of temporal change in the occurrence of CBSD and its causal viruses in DRC, based on surveys conducted during 2016 and 2018. Cassava fields were inspected in Ituri, Nord-Kivu, Sud-Kivu, Tanganyika, and Haut-Katanga provinces within eastern DRC to record foliar incidence and severity of CBSD. Leaf samples were collected for virus detection and species-level identification. New occurrences of CBSD, confirmed by virus diagnostic tests, were recorded in two provinces (Haut-Katanga and Sud-Kivu) and nine previously unaffected territories, covering an area of >62,000 km2, and at up to 900 km from locations of previously published reports of CBSD in DRC. Overall, average CBSD incidence within fields was 13.2% in 2016 and 16.1% in 2018. In the new spread zone of Haut-Katanga, incidence increased from 1.7 to 15.9%. CBSD is now present in provinces covering 321,000 km2, which is approximately 14% of the total area of DRC. This represents a major expansion of the CBSD epidemic, which was only recorded from one province (Nord-Kivu) in 2012. Both Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus were detected in Ituri, Nord-Kivu, and Sud-Kivu, but only CBSV was detected in Haut-Katanga. Overall, these results confirm the increasing threat that CBSD poses to cassava production in DRC and describe an important expansion in the African pandemic of CBSD.
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Affiliation(s)
- C M Casinga
- International Institute of Tropical Agriculture, Kalambo, Bukavu, Democratic Republic of Congo
- Université de Kisangani, Tshopo, Democratic Republic of Congo
| | - R R Shirima
- International Institute of Tropical Agriculture, Dar es Salaam, Tanzania
| | - N M Mahungu
- International Institute of Tropical Agriculture, Kinshasa, Democratic Republic of Congo
| | - W Tata-Hangy
- International Institute of Tropical Agriculture, Kinshasa, Democratic Republic of Congo
| | - K B Bashizi
- International Institute of Tropical Agriculture, Kalambo, Bukavu, Democratic Republic of Congo
| | - C M Munyerenkana
- International Institute of Tropical Agriculture, Kalambo, Bukavu, Democratic Republic of Congo
| | - H Ughento
- Institut National pour l'Etude et la Recherche Agronomique, Bukavu, Democratic Republic of Congo
| | - J Enene
- International Institute of Tropical Agriculture, Kinshasa, Democratic Republic of Congo
| | - M Sikirou
- International Institute of Tropical Agriculture, Kinshasa, Democratic Republic of Congo
| | - B Dhed'a
- Université de Kisangani, Tshopo, Democratic Republic of Congo
| | - G Monde
- Institut Facultaire des Sciences Agronomiques, Yangambi, Democratic Republic of Congo
| | - P L Kumar
- International Institute of Tropical Agriculture, Ibadan, Nigeria
| | - J P Legg
- International Institute of Tropical Agriculture, Dar es Salaam, Tanzania
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Amelework AB, Bairu MW, Maema O, Venter SL, Laing M. Adoption and Promotion of Resilient Crops for Climate Risk Mitigation and Import Substitution: A Case Analysis of Cassava for South African Agriculture. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2021. [DOI: 10.3389/fsufs.2021.617783] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cassava is an important starchy root crop grown globally in tropical and subtropical regions. The ability of cassava to withstand difficult growing conditions and long-term storability underground makes it a resilient crop, contributing to food security. Historically, small-scale farmers have grown cassava as a minor crop in the far north-eastern part of the country. However, there is an initiative to scale up cassava production, with two discrete areas of interest: large-scale production for industrial starch, and expanding its footprint as a food security crop for small-scale farmers, especially in the context of climate change. In this scoping study, production, processing and marketing data for cassava were accessed from the FAO and US Commercial trade databases. Other domestic market and demand analysis case studies were also explored. There is no cassava data available for South Africa. The study indicated that South Africa imports more than 66,000 tons of starch annually, of which 33% is cassava starch, showing the availability of a local market. The potential of cassava for the South African economy is discussed. Significant industrial opportunities exist for the production and use of cassava in South Africa. However, the realization of these opportunities will depend on the reliable supply of good quality cassava roots. However, the lack of a well-established cassava research program, and a lack of an existing value chain for the industrial scale cassava production and processing are barriers to the development of cassava industry in South Africa. As the initial step to the development of a successful cassava industry, high potential germplasm is imported, characterized and bred for local conditions to ensure the sustainable primary production of cassava. Subsequently, industrial value chains will need to be developed as the optimization of the breeding and agronomy of the crop are completed, and yield potentials are quantified in the different regions of the country.
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Genetic Diversity of Mitochondrial DNA of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Associated with Cassava and the Occurrence of Cassava Mosaic Disease in Zambia. INSECTS 2020; 11:insects11110761. [PMID: 33167394 PMCID: PMC7694332 DOI: 10.3390/insects11110761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 11/30/2022]
Abstract
Simple Summary Bemisia tabaci is an important vector that transmits cassava brown streak viruses and cassava mosaic begomoviruses that cause cassava brown streak and cassava mosaic diseases, respectively. In 2013 and 2015 we carried out a study to determine the genetic variability within the Bemisia tabaci complex associated with cassava in Zambia. This investigation made use of mitochondrial cytochrome oxidase I gene sequences of samples collected from selected provinces of Zambia. We found three population subgroups (SGs): SSA1-SG1, SSA1-SG2 and SSA1-SG3 within the sub-Saharan Africa 1 (SSA1) genetic group. Whitefly abundance and the incidence of cassava mosaic disease were both greatest in Western Province, in which the SSA1-SG1 subgroup predominated. Establishing which genetic groups and populations of the B. tabaci species complex are associated with cassava mosaic disease and their distribution in the country is key to guiding the strategic deployment of resources to monitor disease spread and ensure food security for millions of cassava-dependent households. Abstract Bemisia tabaci is an important vector of cassava brown streak viruses and cassava mosaic begomoviruses, the causal agents of cassava brown streak disease and cassava mosaic disease (CMD), respectively. A study was carried out to determine the genetic variability of B. tabaci associated with cassava and the occurrence of CMD in Zambia in 2013 and 2015. Phylogenetic analysis showed the presence of only the sub-Saharan Africa 1 (SSA1) genetic group in Zambia. The SSA1 population had three population subgroups (SGs): SSA1-SG1, SSA1-SG2 and SSA1-SG3. All three SSA1 population subgroups occurred in Western Province. However, only SSA1-SG3 occurred in Eastern Province, while only SSA1-SG1 occurred in North Western and Luapula Provinces. Adult B. tabaci were most abundant in Western Province in 2013 (11.1/plant) and 2015 (10.8/plant), and least abundant (0.2/plant) in Northern Province in both 2013 and 2015. CMD was prevalent in all seven provinces surveyed, with the highest incidence recorded in Lusaka Province in both 2013 (78%) and 2015 (83.6%), and the lowest in Northern Province in both 2013 (26.6%) and 2015 (29.3%). Although SSA1-SG1 occurred at greater abundances than the other subgroups, there was no direct association demonstrated between whitefly subgroup and incidence of CMD. Establishing which B. tabaci genetic groups and populations are associated with CMD and their distribution in the country is a key factor in guiding the development of CMD control strategies for cassava-dependent households.
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Shirima RR, Legg JP, Maeda DG, Tumwegamire S, Mkamilo G, Mtunda K, Kulembeka H, Ndyetabula I, Kimata BP, Matondo DG, Ceasar G, Mushi E, Sichalwe K, Kanju E. Genotype by environment cultivar evaluation for cassava brown streak disease resistance in Tanzania. Virus Res 2020; 286:198017. [PMID: 32461191 PMCID: PMC7450270 DOI: 10.1016/j.virusres.2020.198017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/17/2020] [Accepted: 05/05/2020] [Indexed: 10/25/2022]
Abstract
Cassava brown steak disease (CBSD), caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), is the most important biotic constraint to cassava production in East and Central Africa. Concerted efforts are required to prevent further spread into West Africa as well as to reduce losses in areas already affected. The study reported here was part of a five-country (Kenya, Malawi, Mozambique, Tanzania and Uganda) programme that aimed to identify superior cassava cultivars resistant to CBSD and to disseminate them widely in the region. Seventeen tissue-cultured and virus-tested cultivars were evaluated in Tanzania across nine sites with diverse CBSD inoculum conditions. Experiments were planted using an alpha-lattice design and assessments were made of surrounding inoculum pressure, CBSD foliar and root incidence and root yield at harvest. There were large differences in CBSD infection between sites, with greatest spread recorded from the north-western Lake (Victoria) zone. Differences were driven by Bemisia tabaci whitefly vector abundance and CBSD inoculum pressure. Both CBSV and UCBSV were almost equally represented in cassava fields surrounding experimental plots, although CBSV predominated in the north-west whilst UCBSV was more frequent in coastal and southern sites. However, the incidence of CBSV was much greater than that of UCBSV in initially virus-free experimental plots, suggesting that CBSV is more virulent. Cultivars could be categorised into three groups based on the degree of CBSD symptom expression in shoots and roots. The seven cultivars (F10_30R2, Eyope, Mkumba, Mkuranga1, Narocass1, Nase3 and Orera) in the most resistant category each had shoot and root incidences of less than 20%. Fresh root yield differed between sites and cultivars, but there was no genotype by environment interaction for this trait, probably attributable to the large fertility and soil moisture differences between sites. Susceptible cultivars and the local check performed well in the absence of CBSD pressure, highlighting the importance of exploiting quality and yield traits of local landraces in breeding programmes. Overall, our results emphasized the importance of applying a balanced strategy for CBSD management. This should use both improved and local germplasm resources to generate high yielding cultivars for specific end-user traits, and combine the deployment of improved cultivars with phytosanitary control measures including the use of healthy planting material and planting during periods of reduced CBSD infection.
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Affiliation(s)
| | | | | | | | | | - Kiddo Mtunda
- Tanzania Agricultural Research Institute, Tumbi, Tanzania
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Muzhinji N, Ntuli V. Genetically modified organisms and food security in Southern Africa: conundrum and discourse. GM CROPS & FOOD 2020; 12:25-35. [PMID: 32687427 PMCID: PMC7553747 DOI: 10.1080/21645698.2020.1794489] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The importance of food security and nourishment is recognized in Southern African region and in many communities, globally. However, the attainment of food security in Southern African countries is affected by many factors, including adverse environmental conditions, pests and diseases. Scientists have been insistently looking for innovative strategies to optimize crop production and combat challenges militating against attainment of food security. In agriculture, strategies of increasing crop production include but not limited to improved crop varieties, farming practices, extension services, irrigation services, mechanization, information technology, use of fertilizers and agrochemicals. Equally important is genetic modification (GM) technology, which brings new prospects in addressing food security problems. Nonetheless, since the introduction of genetically modified crops (GMOs) three decades ago, it has been a topic of public discourse across the globe, conspicuously so in Southern African region. This is regardless of the evidence that planting GMOs positively influenced farmer’s incomes, economic access to food and increased tolerance of crops to various biotic and abiotic stresses. This paper looks at the issues surrounding GMOs adoption in Southern Africa and lack thereof, the discourse, and its potential in contributing to the attainment of food security for the present as well as future generations.
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Affiliation(s)
- Norman Muzhinji
- Department of Natural and Applied Sciences, Namibia University of Science and Technology , Windhoek, Namibia
| | - Victor Ntuli
- Department of Biology, National University of Lesotho , Roma, Lesotho
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Muhindo H, Yasenge S, Casinga C, Songbo M, Dhed’a B, Alicai T, Pita J, Monde G. Incidence, severity and distribution of Cassava brown streak disease in northeastern Democratic Republic of Congo. COGENT FOOD & AGRICULTURE 2020; 6:1789422. [PMID: 33718519 PMCID: PMC7909215 DOI: 10.1080/23311932.2020.1789422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 06/20/2020] [Indexed: 06/12/2023]
Abstract
Cassava fields were prospected from two provinces of the Democratic Republic of Congo (Ituri and Haut Uélé) to evaluate the ampleness of Cassava brown streak disease (CBSD) infection. CBSD pressure was determined by assessing the incidence, severity, whitefly abundance and distribution of the disease viruses in the surveyed provinces. A duplex RT-PCR was performed for the simultaneous detection of Ugandan Cassava brown streak virus (UCBSV) and Cassava brown streak virus (CBSV) on 56 cassava leaves sampled in the study area. Our results show a high field CBSD incidence contrasted to a low severity in both provinces. CBSD severity was similar in both provinces (mean disease severity 2). High densities of whitefly were recorded in Ituri province (10 adult whiteflies plant-1) than in Haut Uélé where density was 5 adults plant-1. However, no relation has been found between whitefly density and CBSD incidence and severity on cassava leaf, root and stems. Molecular analysis showed the incidence of single infections of UCBSV was greater than single infections of CBSV and mixed infections of UCBSV and CBSV. Disease incidence was greater in Ituri than in Haut Uélé; molecular incidence was lower than field incidence. Our results raise the need for appropriate CBSD control strategies in DRC.
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Affiliation(s)
- Honoré Muhindo
- Laboratory of Plant Virology & West African Virus Epidemiology (WAVE-East DR Congo), Institut Facultaire des Sciences Agronomiques de Yangambi (IFA-Yangambi), Kisangani, BP 1232 Kisangani, DRC
| | - Sabrine Yasenge
- Faculty of Sciences, Department of Plant Biotechnology, University of Kisangani, BP 2012 Kisangani, DRC
| | - Clérisse Casinga
- International Institute of Tropical Agriculture, IITA-Kalambo, Bukavu, DRC
| | - Médard Songbo
- Laboratory of Plant Virology & West African Virus Epidemiology (WAVE-East DR Congo), Institut Facultaire des Sciences Agronomiques de Yangambi (IFA-Yangambi), Kisangani, BP 1232 Kisangani, DRC
| | - Benoît Dhed’a
- Faculty of Sciences, Department of Plant Biotechnology, University of Kisangani, BP 2012 Kisangani, DRC
| | - Titus Alicai
- National Agriculture Research Organization (NARO), National Crops Resources Research Institute (NaCRRI), Uganda
| | - Justin Pita
- West African Virus Epidemiology (WAVE-Abidjan), Université Félix Houphouët-Boigny (UFHB), BP V34 Abidjan 01, Côte d’Ivoire
| | - Godefroid Monde
- Laboratory of Plant Virology & West African Virus Epidemiology (WAVE-East DR Congo), Institut Facultaire des Sciences Agronomiques de Yangambi (IFA-Yangambi), Kisangani, BP 1232 Kisangani, DRC
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Ferris AC, Stutt ROJH, Godding D, Gilligan CA. Computational models to improve surveillance for cassava brown streak disease and minimize yield loss. PLoS Comput Biol 2020; 16:e1007823. [PMID: 32614829 PMCID: PMC7331984 DOI: 10.1371/journal.pcbi.1007823] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 03/24/2020] [Indexed: 11/19/2022] Open
Abstract
Cassava brown streak disease (CBSD) is a rapidly spreading viral disease that affects a major food security crop in sub-Saharan Africa. Currently, there are several proposed management interventions to minimize loss in infected fields. Field-scale data comparing the effectiveness of these interventions individually and in combination are limited and expensive to collect. Using a stochastic epidemiological model for the spread and management of CBSD in individual fields, we simulate the effectiveness of a range of management interventions. Specifically we compare the removal of diseased plants by roguing, preferential selection of planting material, deployment of virus-free ‘clean seed’ and pesticide on crop yield and disease status of individual fields with varying levels of whitefly density crops under low and high disease pressure. We examine management interventions for sustainable production of planting material in clean seed systems and how to improve survey protocols to identify the presence of CBSD in a field or quantify the within-field prevalence of CBSD. We also propose guidelines for practical, actionable recommendations for the deployment of management strategies in regions of sub-Saharan Africa under different disease and whitefly pressure. Cassava is the second largest source of calories in sub-Saharan Africa and is particularly important for the poorest farmers in the region. Cassava brown streak disease is a viral disease that causes cassava tubers to rot, rendering the roots inedible. Recently, the disease has begun to spread towards major cassava growing regions in West Africa from East Africa, where it continues to cause significant yield losses. Improved approaches for disease control are needed to enable small-holder farmers to prepare for and minimize the impact of the disease when their fields become infected. Using a combination of computational methods and mathematical models enables us to screen a much larger range of potential treatments for their likely effectiveness in managing disease and reducing crop loss than would be possible in conventional field trials, which are expensive and logistically difficult to conduct. Our results indicate that regularly planting part of the field with virus-free cassava greatly improves the yield. Removing visibly infected plants and replanting using visibly uninfected plants also improves yield, even when some of these plants may be infected but not yet showing symptoms. We also show how the survey protocol can be optimized to improve estimates of disease severity leading to more effective tailored advice to farmers in regions with different disease pressures.
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Affiliation(s)
- Alex C. Ferris
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
- * E-mail:
| | | | - David Godding
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
- Farming Data, Cambridge, United Kingdom
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Alicai T, Szyniszewska AM, Omongo CA, Abidrabo P, Okao-Okuja G, Baguma Y, Ogwok E, Kawuki R, Esuma W, Tairo F, Bua A, Legg JP, Stutt ROJH, Godding D, Sseruwagi P, Ndunguru J, Gilligan CA. Expansion of the cassava brown streak pandemic in Uganda revealed by annual field survey data for 2004 to 2017. Sci Data 2019; 6:327. [PMID: 31852893 PMCID: PMC6920376 DOI: 10.1038/s41597-019-0334-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 11/26/2019] [Indexed: 11/26/2022] Open
Abstract
Cassava brown streak disease (CBSD) is currently the most devastating cassava disease in eastern, central and southern Africa affecting a staple crop for over 700 million people on the continent. A major outbreak of CBSD in 2004 near Kampala rapidly spread across Uganda. In the following years, similar CBSD outbreaks were noted in countries across eastern and central Africa, and now the disease poses a threat to West Africa including Nigeria - the biggest cassava producer in the world. A comprehensive dataset with 7,627 locations, annually and consistently sampled between 2004 and 2017 was collated from historic paper and electronic records stored in Uganda. The survey comprises multiple variables including data for incidence and symptom severity of CBSD and abundance of the whitefly vector (Bemisia tabaci). This dataset provides a unique basis to characterize the epidemiology and dynamics of CBSD spread in order to inform disease surveillance and management. We also describe methods used to integrate and verify extensive field records for surveys typical of emerging epidemics in subsistence crops.
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Affiliation(s)
- Titus Alicai
- National Crops Resources Research Institute, Kampala, Uganda
| | - Anna M Szyniszewska
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | | | | | | | - Yona Baguma
- National Crops Resources Research Institute, Kampala, Uganda
| | - Emmanuel Ogwok
- National Crops Resources Research Institute, Kampala, Uganda
| | - Robert Kawuki
- National Crops Resources Research Institute, Kampala, Uganda
| | - Williams Esuma
- National Crops Resources Research Institute, Kampala, Uganda
| | - Fred Tairo
- Mikocheni Agricultural Research Institute, Dares Salaam, Tanzania
| | - Anton Bua
- National Crops Resources Research Institute, Kampala, Uganda
| | - James P Legg
- International Institute of Tropical Agriculture, Dares Salaam, Tanzania
| | - Richard O J H Stutt
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - David Godding
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
- Farming Data, Cambridge, United Kingdom
| | - Peter Sseruwagi
- Mikocheni Agricultural Research Institute, Dares Salaam, Tanzania
| | - Joseph Ndunguru
- Mikocheni Agricultural Research Institute, Dares Salaam, Tanzania
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Chikoti PC, Mulenga RM, Tembo M, Sseruwagi P. Cassava mosaic disease: a review of a threat to cassava production in Zambia. JOURNAL OF PLANT PATHOLOGY : AN INTERNATIONAL JOURNAL OF THE ITALIAN PHYTOPATHOLOGICAL SOCIETY 2019; 101:467-477. [PMID: 31983872 PMCID: PMC6951474 DOI: 10.1007/s42161-019-00255-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/30/2019] [Indexed: 05/18/2023]
Abstract
Cassava (Manihot esculenta Crantz) is one of the most important root staple crops in Zambia. An estimated 30% of Zambians, over 4 million people, consume cassava as part of their daily diet. Cassava is mostly grown by subsistence farmers on fields of less than 1 ha. Cultivation of cassava is hampered by several biotic constraints, of which cassava mosaic disease (CMD) is currently the most important factor limiting cassava production in Zambia. CMD occurs in all the cassava-growing provinces and accounts for 50% to 70% of yield losses countrywide. Strategies to counter CMD were initiated in the early 1990s and included the release of CMD-resistant cassava cultivars. However, efforts to control CMD are limited because few growers plant these cultivars. More recently, to address the CMD problem, regular disease monitoring and diagnostic capabilities have been strengthened, and there is increased support for screening breeders materials. CMD is a rising threat to cassava production in Zambia. This review of CMD research on disease surveillance, CMD spread, yield losses, awareness campaigns and control options in Zambia over the past 25 years informs future control efforts and management strategies.
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Affiliation(s)
- Patrick Chiza Chikoti
- Zambia Agriculture Research Institute, Mt. Makulu Central Research Station, P/B 7, Chilanga, Zambia
| | - Rabson Mpundu Mulenga
- Zambia Agriculture Research Institute, Mt. Makulu Central Research Station, P/B 7, Chilanga, Zambia
| | - Mathias Tembo
- Zambia Agriculture Research Institute, Mt. Makulu Central Research Station, P/B 7, Chilanga, Zambia
| | - Peter Sseruwagi
- Mikocheni Agricultural Research Institute, P.O. Box 6226, Dar es Salaam, Tanzania
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