TABLE CONTENTS

Practical Site-specific Nematicide Delivery on Cotton Farms in the Mid-
South USA
Monfort, W.S. (1), T.L. Kirkpatrick (2), A.H. Khalilian (3) & J.D. Mueller (3)
(1) University of Arkansas, Lonoke Extension Center, Lonoke, AR 72086, USA; (2) University of Arkansas,
Southwest Research and Extension Center, Hope, AR 71801, USA; (3) Clemson University, Edisto Research
and Education Center, Blackville, SC 29817, USA.
Cotton growers in the southern U.S. routinely include the application of either 1,3-
dichloropropene (Telone II) or aldicarb (Temik) in their farming operations for nematode
management. The most economically important nematodes in cotton are Meloidogyne
incognita and Rotylenchulus reniformis. Nematicide applications are made at a single rate on
a whole-field basis, and decisions to apply these chemicals are usually based on assay of a
single composite soil sample arbitrarily collected from each field. However, nematode
distributions and associate damage are not typically uniform in most fields. Soil texture is a
key factor influencing the reproductive success and damage potential of these nematode
species and on the crop. An understanding of soil textural changes within individual fields
could allow more efficient sampling for nematode detection and quantification and provide a
platform for determining strategies for site-specific nematicide placement. In field
investigations (2005 & 2007), mobile soil electrical conductivity (EC) meters (Veris
Technologies) were used to estimate and map site-specific soil textural variations within a
production field in Northeast Arkansas. The soil EC maps were used to identify soil textural
regions (zones) that were sampled individually for nematodes. Nematode population
densities from each zone were then compared with known damage threshold values, and
prescription application maps for site-specific placement of 1,3-dichloropropene were
developed. Site-Specific applications of 1,3-dichloropropene were compared to an untreated
control and a single 3 gal/acre rate of 1,3-dichloropropene. Results in this field indicated that
cotton yield was comparable in zones receiving site-specific nematicide application to that
where a single rate was applied, but 37 to 42 percent less chemical was applied with the sitespecific
approach. Both approaches resulted in significantly greater yield than where no
nematicide was applied.
Considering Field Physical Characteristics in Assessing Risk and
Delineating Nematode Management Zones
Davis, R.F. (1), B.V. Ortiz (2), C. Perry (2), D. Sullivan (3), B. Kemerait (4), G. Vellidis (2)
& K. Rucker (5)
(1) USDA-ARS, CPMRU, Tifton, GA 31793, USA; (2) Dept. of Biological and Agricultural Engineering, Univ.
of Georgia, Tifton, GA 31793, USA; (3) USDA-ARS, SEWRU, Tifton, GA 31793, USA; (4) Dept. of Plant
Pathology, Univ. of Georgia, Tifton, GA 31793, USA; (5) Univ. of Georgia, Cooperative Extension Service,
Tifton, GA 31793, USA.
Site-specific management (SSM) of nematodes requires identifying factors affecting
nematode distribution, nematode population density, and nematode-induced yield losses, and
then using that information to predict where nematode management will cost-effectively
reduce yield loss. Using cotton (Gossypium hirsutum) as a model system, we accomplished
this by 1) using multiple regression analysis to evaluate the relationship between cotton yield,
soil physical and chemical properties, and southern root-knot nematode (RKN, Meloidogyne
incognita) population density to identify factors most strongly affecting yield; 2) using the
most important factors affecting yield to create a logistic regression model which predicts the
5 th International Congress of Nematology, 2008 136