What are Nematodes?

Nematodes are microscopic pathogens that live in the soil and attack a plants root system. In Georgia, the root knot nematode (RKN) is considered one of the most critical pest problems facing producers today.

Where are Nematodes found?
Nematodes are found all across the U.S. Cotton Belt.  In GA, RKN have been found to infest 68% of sampled fields in all 67 cotton producing counties.  Research by nematologists have shown that RKN prefer sandy soils and consequently aggregate in sandy patches of fields. 

What are the effects of Nematodes?
RKN damage the roots of cotton plants by forming knots on the roots.  These knots interfere with the plants’ ability to take up water and nutrients and result in stunted plant growth and reduced yields.

 What type of Nematode research is going on at UGA-Tifton?
As part of a large project funded in part by Cotton Inc. and the Georgia Cotton Commission, the Precision Farming Team at the University of Georgia has been evaluating a number of techniques for delineating areas within fields at high risk for RKN.  Because traditional sampling for RKN is expensive, the project has focused on identifying field properties which can easily and economically measure RKN and also serve to identify high risk areas.

The fact that RKN prefer sandy areas has encouraged us and other research teams to find ways to rapidly measure soil texture – either directly or indirectly.  One of the most promising techniques is to directly measure soil electrically conductivity (soil EC).  Soil electrical conductivity is a function of soil texture and soil moisture.  Sandy soils produce low soil EC while heavier soils result in higher values of soil EC.  Different instruments have been developed to measure soil EC but one of the most popular is the VERIS® 3100.  The VERIS® 3100 instrument has six coulter-electrodes (disks) mounted on a toolbar (Figure 2).  As the veris is pulled through the field, one pair of disks transmits an electrical current into the soil while another pair of disks measures the drop in voltage.  The separation between the disks determines the depth to which soil EC can be measured.  In the most commonly used configuration, soil EC is measured simultaneously from 0-1 ft (shallow) and 0-3 ft (deep).

 In addition to directly measuring soil EC, we are also evaluating other promising methods for indirectly measuring soil texture.  These include:

  1. Using real time kinematic (RTK) GPS to rapidly create detailed topographic maps of fields.  Elevation and slope of the terrain frequently dictate where coarse textured soil particles are deposited by erosion. 
  2. Soil color is generally associated with differences in soil texture.  Bare soil aerial photographs or images taken from satellites can be used to identify these features.


Product names are provided for information only and do not imply endorsement by the University of Georgia or the United States Department of Agriculture – Agricultural Research Service.

Project Leader: Calvin Perry
Contact Info:
Affiliation: University of Georgia
Stripling Irrigation Research Park
8207 Hwy 37
Camilla, GA 31730

Project Leader: Brenda V. Ortiz
Contact Info:
Affiliation: Auburn University
204 Extension Hall
Auburn University, AL 36849