TABLE CONTENTS

probability of yield loss due to RKN (assess risk); and 3) translating the model predicting the
probability of yield loss into field maps which delineate areas with different levels of
probability (risk) of yield loss which can then be used as management zones (MZ) for SSM.
The factors most useful for delineating MZ were soil electrical conductivity (EC, a proxy for
soil texture), elevation, slope, and normalized difference vegetation index (NDVI), though
soil EC was the single most important factor. Models created from multiple fields in 2005
and 2006 were used to create a MZ map for a field in 2007. Nematicide treatments were
randomized and replicated in each MZ, and nematicides were shown to have a much greater
effect in MZ predicted to have the greatest risk for loss to RKN. Though the most expensive
nematicide treatments generally led to the greatest yield increases in all MZ, they were the
most cost-effective treatments only in MZ identified as higher risk for yield loss from RKN;
in lower risk MZ, less expensive treatments were the most cost-effective. Therefore, MZ
based on field physical characteristics will allow SSM of nematodes in some fields.
Cost Effectiveness of Precision Nematode Management
Mueller, J., A. Khalillain & W. Henderson
Edisto R.E.C., Clemson University, Blackville, South Carolina, 29817
Precision nematode management systems can be cost efficient in a number of interlocking
ways. First they can apply nematicides in a more precise manner than older gravity flow
material. Systems developed at Clemson University can apply 1,3-dichloropene with a
maximum absolute error rate of 6.7% and an average overall error rate of -2.1%. A newly
developed aldicarb applicator can operate with measurement errors of -3 to 4.2 with a mean
error of 1.1%. Aldicarb application error rates on older equipment can exceed 10%.
Traditional grid sampling can be replaced with nematode distribution maps based on models
relating nematode distribution to soil types determined using a soil electrical conductivity
(EC) meter. Instead of taking, processing and paying for 10 to 20 samples per hectare a single
pass with an EC meter can map an entire field for the cost of collecting and processing 2 to 3
traditional samples. By combining EC based maps with site specific application techniques
precision nematicide application can be cost effective. An example of site specific
application is a test conducted in 2002 in South Carolina. In a 10 acre field infested with H.
columbus utilizing map based variable rate aldicarb applications based on % sand generated
using an EC meter resulted in a 5% higher yield and 34% lower nematicide usage compared
to a single rate application. Variable rate applications of 1,3-dicloropropene also increased
yield 5% while decreasing nematicide usage 78% compared to a single rate application.
Projects are currently underway to create lower cost application systems that are also simpler
to operate.
5 th International Congress of Nematology, 2008 137