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Plant-parasitic nematodes inhabit the soil or plant parts they infect. To collect a soil sample for a nematode assay, gather random sub-samples in a zigzag pattern from the target area. This procedure is similar to collecting a standard soil fertility sample, but the key differences are in handling and storage.
Field Sampling Guidelines
Field Sampling Guidelines
To obtain an accurate nematode assay, follow these systematic field collection procedures:
Strategy and Patterns
Divide a pivot circle field or a block field into uniform sections. Sections of 5 acres or less are scientifically recommended for field crops, and 2 acres for orchards. However, you may divide a field systematically into 4 quadrants or 8 pizza-shaped sections based on collection practicality.
Gather random sub-samples in a "W" or "zig-zag" pattern, similar to soil fertility testing.
Sample separately for different cropping histories, soil types, or crop health statuses.
Core Collection and Depth
Collect 10 to 20 cores per 5-acre block using an auger sampler.
Extract primary cores from the top 12 inches where most nematodes reside.
Collect secondary (12-24") and tertiary (24-36") cores to capture deeper populations.
Consolidation
Combine sub-samples of each depth separately into a single container as they are collected, then proceed to sample preparation.
Sample Preparation
Sample Preparation
When it comes to plant-parasitic nematodes and disease testing samples, fresher is always better.
Mix the collected soil sub-samples gently and thoroughly.
Place approximately 1 pint (2 cups or ~500 cc) of soil into a sampling bag or quart-sized plastic zip bag.
This 1-pint volume is sufficient for both nematode and soil-borne disease analysis (e.g., soil DNA testing).
Always use proper sampling bags or plastic zip bags, and completely avoid cloth or paper bags.
Include at least 4 oz (~100 grams) of fine feeder roots if you require root testing.
Prioritize roots showing symptoms like galling, thickening, bunching, or soil adherence.
Seal bags securely to prevent drying and to retain natural soil moisture.
Label each sample on the outside of the bag with your name, address, field ID (or short identifier), and the collection date.
Do not place paper labels inside the sampling bag, as moisture will destroy them.
Storage and Shipping
Storage and Shipping
Protect samples from drying, extreme heat, freezing temperatures, and direct sunlight.
If samples are collected for soil-borne disease analysis (soil DNA testing), keep them in a cooler with ice packs or refrigerate them until they are sent to the laboratory.
Perishable plant material samples should be refrigerated immediately until dispatch.
If refrigeration is unavailable, soil nematode samples may be temporarily stored at room temperature for 24-48 hours in sealed bags if there is a delay in dropping-off or shipping.
Complete a Testing Submission Form detailing the required test, sample ID, depth, crop type, mailing address, phone number, and email address.
Send the samples and the completed submission form promptly to the laboratory.
Pre-book your tests.
Email a digital copy of the sample submission form.
Ideally, collect and dispatch samples early in the week to guarantee prompt processing.
If you are interested in having more information, you may check the following links:
The Hows and Whys of Soil Testing [Video] - Dr. Joan Davenport, WSU Crop and Soil Sciences Dept.
A Guide to Collecting Soil Samples for Farms and Gardens [online] - Oregon State University
Soil Testing [online] - Ohio State University Extension
Comprehensive Assessment of Soil Health [pdf] - Cornell University
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