Purpose of Soil Sampling: To accurately determine nematode species, population distributions and densities in a specific area.
Factors Influencing Distribution and Density: Time of year, previous crop, soil texture, soil moisture, and nematode management practices used. If nematodes are present, distribution is generally patchy in a field.
Best Time to Collect Soil Samples: Guidelines vary between states however, summer or late fall is recommended. Populations are usually low in spring and build through the growing season to reach peak densities at harvest. Soil samples should be taken before cultivation when rows are still in place because nematodes concentrate around the root zone.
Number of Samples to be Collected: The number of samples to be taken is usually based on the value of the information to be gained compared to the cost of collecting the samples, plus laboratory fees for extracting the nematodes.The greater the number of samples collected, the more accurate and reliable the estimate will be.
Plans Prior to Collecting Soil Samples: It is important to look for clues that may be present in the field prior to sampling.
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Review previous cropping patterns and yield maps.
- Assess soil texture and changes in the field.
- Identify weak spots in the field and look for plant symptoms.
- Divide the field into areas based on crop history and soil type to increase cost effectiveness of sampling. Sampling is more valuable in a divided field, because the final estimate is more accurate and reliable.
- After the field is divided into areas based on crop history soil type, and yield maps, then subdivide these areas into blocks of about 10 acres. Treat each area where growth has been poor as a separate block, even if it is smaller than other blocks.
Zone Sampling: Zones are a means of breaking the field down based on soil texture. The use of ECa and the Veris Soil EC Mapping System are used to develop zones. Veris machine using GPS provide an accurate estimate of soil texture across the field. A map can be made showing the areas of the field with the lightest to heaviest soil. The field can be broken down into a number of zones but usually three to seven based on soil variability present within the field. Once an EC map has been developed, each zone can be sampled separately. A total of 10-15 soil cores can be systematically collected from each zone to thoroughly represent it. If a field is very large or zones separated within the field, then additional samples should be collected from these areas.
Collecting Soil Samples: Each sample should represent approximately 10 acres or a zone of a similar soil type and should consist of at least 20 individual soil cores. Soil probes, which are steel tubes about one-inch in diameter, are commonly used to extract soil cores. Each core should be taken to a depth of at least 6 to 12 inches. Place soil cores in a bucket and thoroughly mix. Place about a quart of mixed soil in a plastic bag and seal it to prevent drying.
Caring for Soil Samples: Soil samples require SPECIAL care to assure survival of the living nematodes in the soil. Laboratory information on a dried soil sample will not accurately reflect the true field condition.
- Handle each nematode soil sample like a carton of milk.
- Keep the sample cool, but not frozen. During collection of samples, keep them in an ice chest in the shade.
- Transport samples in a pre-cooled ice chest to prevent overheating.
- Deliver samples to the diagnostic laboratory as soon as possible. Use overnight delivery if possible.
Provide Diagnostic Laboratory with All Pertinent Information about the Situation:
- Current crop, past crop, intended crop, date of sampling, location, grower name.
- Description of all specific problems. List nematode(s) suspected in the area.
State Nematode Diagnostic Laboratories for Soil Sample Analyses: (For costs of analyses, contact the laboratory or your county agent).
AlabamaThe Plant and Nematode Diagnostic Laboratory
164C ALFA Agricultural Services and Research Building
961 South Donahue Drive
Auburn University
Auburn, AL 36849
Arkansas
Nematode Diagnostic Laboratory
Southwest Research and Extension Center
362 Highway 174 North
Hope, AR 71801
Arizona
Department of Plant Pathology
University of Arizona
204 Forbes Building
Tucson, AZ 85721
California
For the commercial laboratory nearest you, contact your local University of California Cooperative Extension Office.
Florida
IFAS Nematode Assay Lab,
University of Florida,
Building 78, Mowry Rd.,
Gainesville, FL 32611.
352- 392-1994
nemalab@ifas.ufl.edu
Georgia
University of Georgia
Nematode Assay Laboratory
Plant Pathology Department
4 Towers Building
4 Towers Road
Athens, GA 30602-4356
Louisiana
Nematode Advisory Service
Louisiana State University
302 Life Sciences Building
Baton Rouge, LA 70803-1900
Mississippi
Extension Plant Pathology Lab
P.O. Box 5446
190 Bost North Room 9
Mississippi State University
Mississippi State, MS 39762-9612
Missouri
Nematode laboratory
23 Mumford Hall
Columbia, MO 65211
573-882-3019
soilplantlab.missouri.edu/nematode
New Mexico
Plant Diagnostic Clinic
New Mexico State University
Skeen Hall Room W242
945 College Ave.
Las Cruces, N.M. 88003-8003
Phone: 575-646-1965
North Carolina
North Carolina Department of Agriculture
Agronomic Division
Nematode Advisory Service
4300 Reedy Creek Road
Raleigh, NC 27607-6405
South Carolina
Nematode Assay Lab
511 Westinghouse Road
Pendleton, SC 29670
864-656-2068
864-646-2133
nemalab@clemson.edu
Texas
Texas Plant Disease Diagnostic Laboratory
1500 Research Parkway, Suite A130
Texas A&M University Research Park
College Station, TX 77845
979-845-8032,
plantclinic@ag.tamu.edu
Texas High Plains Plant Diagnostic Laboratory
6500 Amarillo Blvd. W.,
Amarillo, TX 79106.
806-677-5616
rdfrench@ag.tamu.edu
(For costs of analyses, contact the laboratory or your county agent).
Alabama
The Plant and Nematode Diagnostic Laboratory
101 Extension Hall
Auburn University
Auburn, AL 36849
Arkansas
Nematode Diagnostic Laboratory
Southwest Research and Extension Center
362 Highway 174 North
Hope, AR 71801
Arizona
M. A. McClure
Department of Plant Pathology
University of Arizona
204 Forbes Building
Tucson, AZ 85721
California
For the commercial laboratory nearest you, contact your local University of California Cooperative Extension Office.
Florida
Nematode Clinic
Attn: Robert Dunn
Department of Entomology & Nematology
University of Florida
Gainesville, FL 32611
Georgia
University of Georgia
Nematode Assay Laboratory
Plant Pathology Department
4 Towers Building
4 Towers Road
Athens, GA 30602-4356
Louisiana
Nematode Advisory Service
Louisiana State University
302 Life Sciences Building
Baton Rouge, LA 70803-1900
Mississippi
Extension Plant Pathology Department
Mississippi State University
P.O. Box 5446
Mississippi State, MS 39762
Missouri
Nematode Assay Laboratory
University of Missouri
103 Waters Hall
Columbia, MO 65211
New Mexico
Leyendecker Plant Science Research Center
New Mexico State University
Las Cruces, NM 88003-0003
North Carolina
Attn: Jack Imbriani
North Carolina Department of Agriculture
Agrinomic Division
Nematode Advisory Service
4300 Reedy Creek Road
Raleigh, NC 27607-6405
South Carolina
Nematode Assay Laboratory
Clemson University
Cherry Road
Clemson, SC 29634
Tennessee
Mr. T. S. Stebbins, Laboratory Diagnostician
Tennessee Plant Diagnostic Center
5201 Merchant Drive
Nashville, TN 37211-5201
Texas
Plant Disease Diagnostic Laboratory
Plant Pathology Department
Texas A&M University
120 Peterson Hall
College Station, TX 77843-2132