Spatial and Spatiotemporal Pattern Analysis of Coconut Lethal Yellowing in Mozambique

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dc.contributor.authorBonnot, F.
dc.contributor.authorde Franqueville, H.
dc.contributor.authorLourenco, E.
dc.date.accessioned2014-05-19T09:14:29Z
dc.date.available2014-05-19T09:14:29Z
dc.date.issued2010
dc.description.abstractCoconut lethal yellowing (LY) is caused by a phytoplasma and is a major threat for coconut production throughout its growing area. Incidence of L Y was monitored visually on every coconut tree in six fields in Mozambique for 34 months. Disease progress curves were plotted and average monthly disease incidence was estimated. Spatial patterns of disease incidence were analyzed at six assessment times. Aggregation was tested by the coefficient of spatial autocorrelation of the l1-binomial distribution of diseased trees in quadrats. The binary power law was used as an assessment of overdispersion across the six fields. Spatial autocorrelation between symptomatic trees was measured by the BB join count statistic based on the number of pairs of diseased trees separated by a specific distance and orientation, and tested using permutation methods. Aggregation of symptomatic trees was detected in every field in both cumulative and new cases. Spatiotemporal patterns were analyzed with two methods. The proximity of symptomatic trees at two assessment times was investigated using the spatiotemporal BB join count statistic based on the number of pairs of trees separated by a specific distance and orientation and exhibiting the first symptoms of L Y at the two times. The semivariogram of times of appearance of L Y was calculated to characterize how the lag between times of appearance of L Y was related to the distance between symptomatic trees. Both statistics were tested using permutation methods. A tendency for new cases to appear in the proximity of previously diseased trees and a spatially structured pattern of times of appearance of L Y within clusters of diseased trees were detected, suggesting secondary spread of the disease.en_US
dc.identifier.citationPHYTOPATHOLOGY Vol. 100, No.4, 2010,pp300-312en_US
dc.identifier.urihttp://hdl.handle.net/123456789/1466
dc.language.isoenen_US
dc.subjectspatial pattern analysis
dc.subjectspatiotemporal pattern analysis
dc.subjectcoconut
dc.subjectlethal yellowingl
dc.titleSpatial and Spatiotemporal Pattern Analysis of Coconut Lethal Yellowing in Mozambiqueen_US

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