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Title: Geostatistical Analysis of the Spatial Variability of Cotton-Parasitic Nematodes and the Factors Favoring its Occurrence

Author
item ORTIZ, B - UNIVERSITY OF GEORGIA
item Sullivan, Dana
item PERRY, C - UNIVERSITY OF GEORGIA
item VELLIDIS, G - UNIVERSITY OF GEORGIA

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/9/2007
Publication Date: 1/9/2007
Citation: Ortiz, B.V., Sullivan, D.G., Perry, C., Vellidis, G. 2007. Geostatistical Analysis of the Spatial Variability of Cotton-Parasitic Nematodes and the Factors Favoring its Occurrence [abstract]. 2007 National Cotton Council Beltwide Cotton Conference.

Interpretive Summary: Delineation of management zones for a site-specific management of cotton-parasitic nematodes requires the study of their spatial and temporal variability. If field-scale distributions of nematodes spatially correlate with specific biotic or abiotic conditions present in the field, those conditions can be used as surrogate data to identify risk areas of cotton yield reduction due to nematode infection. A systematic sampling design with square grids of 0.20 ha in size was applied on 10 cotton fields in South Georgia in 2005 and 2006. The study involved mapping the spatial variability of southern root knot nematode (Melodogyne incognita) relationships with soil texture, soil electrical conductivity, elevation, slope, and canopy spectral reflectance from multispectral images collected every month during the growing season. Areas having a high probability of nematode infestation will be identified.

Technical Abstract: Delineation of management zones for a site-specific management of cotton-parasitic nematodes requires the study of their spatial and temporal variability. If field-scale distributions of nematodes spatially correlate with specific biotic or abiotic conditions present in the field, those conditions can be used as surrogate data to identify risk areas of cotton yield reduction due to nematode infection. A systematic sampling design with square grids of 0.20 ha in size was applied on 10 cotton fields in South Georgia in 2005 and 2006. The study involved the analysis of the spatial variability of the southern root knot nematode (Melodogyne incognita) sampled three times during every growing season, distributions and its relationship with soil texture, soil electrical conductivity, elevation, slope, and canopy spectral reflectance from multispectral images collected every month during the growing season. The study of the spatial variability based on geostatistical analyses involved the calculation of semivariograms, identification of the degree of spatial structure, kriging interpolations, and the validation of the kriging estimations using a random selection of a subset of data points from every variable under study. Areas having a high probability of nematode populations greater than established threshold populations will be identified via indicator and disjunctive kriging.