Analysis and Mapping of the Spatial Spread of African Cassava Mosaic Virus Using Geostatistics and the Kriging Technique

Lecoustre, René; Fargette, Denis; Fauquet, Claude; Reffye, Philippe de

doi:10.1094/phyto-79-913

Cited by 39 publications

(27 citation statements)

References 12 publications

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“…The development and recent application of geographical information systems, geostatistics, and the Kriging technique to plant pathology offer an alternative approach to predict and monitor changes in plant pathogen populations (12,17). For the future it is important to develop a spatial simulation model to understand the influence of various ecological and genetic factors on the distribution and potential change of X. axonopodis pv.…”

Section: Vol 70 2004 Xanthomonas Genetic Structure and Population Dmentioning

confidence: 99%

Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

Restrepo

Vélez

Duque

et al. 2004

Appl Environ Microbiol

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Restriction fragment length polymorphisms (RFLPs) were used to study the population genetics and temporal dynamics of the cassava bacterial pathogen Xanthomonas axonopodis pv. manihotis. The population dynamics were addressed by comparing samples collected from 1995 to 1999 from six locations, spanning four different edaphoclimatic zones (ECZs). Forty-five different X. axonopodis pv. manihotis RFLP types or haplotypes were identified between 1995 and 1999. High genetic diversity of the X. axonopodis pv. manihotis strains was evident within most of the fields sampled. In all but one site, diversity decreased over time within fields. Haplotype frequencies significantly differed over the years in all but one location. Studies of the rate of change of X. axonopodis pv. manihotis populations during the cropping cycle in two sites showed significant changes in the haplotype frequencies but not composition. However, variations in pathotype composition were observed from one year to the next at a single site in ECZs 1 and 2 and new pathotypes were described after 1997 in these ECZs, thus revealing the dramatic change in the pathogen population structure of X. axonopodis pv. manihotis. Disease incidence was used to show the progress of cassava bacterial blight in Colombia during the 5-year period in different ecosystems. Low disease incidence values were correlated with low rainfall in 1997 in ECZ 1.Cassava, Manihot esculenta Crantz, is a starchy root crop that is among the most important tropical foods. About 80% of the cassava produced is consumed in developing countries and constitutes the principal carbohydrate source for more than 500 million people (14). Cassava bacterial blight (CBB) has caused extensive damage to the crop during the past 2 decades (6, 14, 30). The causal agent, Xanthomonas axonopodis pv. manihotis, can induce a wide variety of symptoms, including angular leaf spots, blight, gum exudation, stem cankers, shoot wilt, vascular necrosis, and dieback (15). Resistance, which has been identified in M. esculenta and the wild relative Manihot glaziovii, is thought to be polygenic and additively inherited (9). Molecular markers have been employed to construct a genetic map of the cassava genome consisting of several hundred markers (8). The mapping of CBB resistance has recently been reported both in controlled conditions and in the field (10, 11). Resistance to X. axonopodis pv. manihotis strains is controlled by several quantitative trait loci (QTL) located in different linkage groups, suggesting a specific interaction between the plant and the pathogen. Some of these QTL are specific to one strain, showing the complexity of this host plant-pathogen interaction (10). Since 1983, the entire cassava breeding strategy has been based on improving varieties for different edaphoclimatic zones (ECZs) (1). The ECZs were defined according to the importance of cassava production in that region, climatic conditions, predominant soil type, and pest and disease problems (2). Seven zones exist: ECZ 1, subhumid tropics;...

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Section: Vol 70 2004 Xanthomonas Genetic Structure and Population Dmentioning

confidence: 99%

Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

Restrepo

Vélez

Duque

et al. 2004

Appl Environ Microbiol

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“…Geostatistics were first applied to analyzing patterns of CMD spread in the early 1990s in Ivory Coast (Lecoustre et al 1989), although this comprised a field-level study and did not involve mapping. Kriging and map-based spatial analysis were first used for CMD in a study that compared the results of three different types of survey in Rwanda and Burundi conducted between and 2008(Bouwmeester et al 2012.…”

mentioning

confidence: 99%

Spatial Analysis of Temporal Changes in the Pandemic of Severe Cassava Mosaic Disease in Northwestern Tanzania

et al. 2017

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To improve understanding of the dynamics of the cassava mosaic disease (CMD) pandemic front, geospatial approaches were applied to the analysis of 3 years' data obtained from a 2-by-2°(approximately 222-by-222 km) area of northwestern Tanzania. In total, 80 farmers' fields were assessed in each of 2009, 2010, and 2011, with 20 evenly distributed fields per 1-by-1°q uadrant. CMD-associated variables (CMD incidence, CMD severity, vector-borne CMD infection, and vector abundance) increased in magnitude from 2009 to 2010 but showed little change from 2010 to 2011. Increases occurred primarily in the two westernmost quadrants of the study area. A pandemic "front" was defined by determining the values of CMD incidence and whitefly abundance where predicted disease gradients were greatest. The pandemic-associated virus (East African cassava mosaic virus-Uganda) and vector genotype (Bemisia tabaci sub-Saharan Africa 1-subgroup 1) were both present within the area bounded by the CMD incidence front but both also occurred ahead of the front. The average speed and direction of movement of the CMD incidence front (22.9 km/year; southeast) and whitefly abundance front (46.6 km/year; southeast) were calculated, and production losses due to CMD were estimated to range from US$4.3 million to 12.2 million.Cassava mosaic disease (CMD) is one of the most important constraints to cassava production in sub-Saharan Africa, and causes more than US$1 billion of losses annually (Legg et al. 2006;Thresh et al. 1997). The disease is caused by several species of cassava mosaic begomoviruses (CMB) (family Geminiviridae, genus Begomovirus) (Bock and Woods 1983), which are propagated through planting infected stem cuttings and transmitted persistently by the whitefly Bemisia tabaci (Genn.) (Dubern 1994). In the late 1980s and early 1990s, an epidemic of unusually severe CMD emerged in Uganda ) and subsequently spread to affect a large area of East and Central Africa (Legg 1999;Legg et al. 2006;Otim-Nape et al. 1997). A novel virus recombinant, East African cassava mosaic virus-Uganda (EACMV-UG) was shown to be associated with this "pandemic" (Zhou et al. 1997) and gave rise to unusually severe disease symptoms through a synergistic interaction with a second CMB, African cassava mosaic virus (ACMV). Severe CMD spread rapidly at estimated speeds of 20 to 30 km/year (Otim-Nape et al. 1997), driven by superabundant populations of B. tabaci (Legg and Ogwal 1998). Almost 30 years after the first reports of severe CMD from Uganda, the severe CMD pandemic continues to spread, currently advancing southward through eastern Democratic Republic of Congo and westward through central Cameroon. The pandemic of severe CMD continues to pose a threat to the world's largest producer of cassava, Nigeria, lying immediately to the west of Cameroon.Monitoring and surveillance activities have played a vital role in the CMD management effort as newly affected areas have been identified, facilitating the targeting of control interventions. An important aspect...

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“…This precise management makes it possible to reduce pesticide use (Weisz et al, 1996) and delay the onset of pesticide resistance by creating temporary dynamic shelters (Fleischer et al, 1999), thus allowing for economic savings. Carvalho and Ampélio (2010) indicate that the maps obtained by kriging are appropriate for disease monitoring and management and useful for detecting changes in spatial disease patterns through time (Lecoustre et al, 1989). The results of this study, in which spatial distribution of S. reilianum are represented in the study maps, were non-uniform in 100% of the area of the sampled locality, which is consistent with the distribution of Colletotrichum kahawae in coffee, as obtained by Mouen-Bedimo et al (2007), and in olive trees (Verticillium dahlia), as studied by Rodríguez et al (2009).…”

Section: Discussionmentioning

confidence: 99%

Determination of spatiotemporal stability of corn head smut(Sporisorium reilianum) by SADIE

et al. 2012

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Knowledge about the spatiotemporal stability and distribution of the disease is important for the development of integrated management programs. The present study was performed to model the spatial distribution of S. reilianum from 2006 to 2009 using geostatistic techniques and to determine the spatiotemporal stability of corn head smut via a spatial analysis by distance indices (SADIE) and the Cramer-von Mises test. The incidence of the disease was determined in 100 corn parcels located in Santa Magdalena Valle de Bravo Municipality, and the parcel locations were determined with dGPS. The spatial distribution analysis was performed using spatial statistics (Geostatistic and SADIE). Aggregation maps were developed; and the long term spatiotemporal stability was determined with the Cramer-von Mises test and the SADIE association index. The results showed that geostatistics were able to establish S. reilianum spatial patterns, visualizing its centers of aggregation through elaborated maps. Such aggregation enables adequate management actions in terms of points or specific sites. The association index of SADIE (I m ) and the bi-variable Cramer-von Mises (Ψ) proof make it possible to determine the spatiotemporal stability of the disease over the four years of the study.

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Analysis and Mapping of the Spatial Spread of African Cassava Mosaic Virus Using Geostatistics and the Kriging Technique

Cited by 39 publications

References 12 publications

Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

Spatial Analysis of Temporal Changes in the Pandemic of Severe Cassava Mosaic Disease in Northwestern Tanzania

Determination of spatiotemporal stability of corn head smut(Sporisorium reilianum) by SADIE

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