Geospatial Solutions For Precision Management Of Cotton Root Knot Nematodes

Abstract

A central issue in cotton ( Gossypium) production is the reduction of yield by root knot nematodes (Meloidogyne incognita). Typically, nematode density is normally estimated by taking soil samples. However this method is expensive, and in some cases the samples taken from the fields do not accurately represent the spatial variability in nematode distributions. The main goal of this paper is to delineate nematode management zones and reduce field scale variability in nematodes for improved site specific management. The density of cotton root knot nematodes (RKN) in five cotton fields was measured four times during the growing season in 2005. Soil electrical conductivity (ECa), elevation, and remotely sensed data were collected as indirect indicators of nematode spatial distributions. A canonical analysis was used to determine which variables explained the greatest amount of variability in root knot nematodes. These variables were entered into a fuzzy clustering algorithm and used to delineate management zones. NDVI and elevation showed significant advantages in reducing the RNK within-zone variability compared to the whole field. However, in more uniform fields, zone delineation was less successful. Future research will evaluate this methodology over more variable soils and elevations and determine the utility of this methodology for the development of a risk index as well as for site-specific soil sampling and variable rate nematicide treatments.