Extraction of SCN cysts from soil

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These procedures are part of our routine soil processing for SCN egg counts.

Procedure for manual cyst extraction

After preparing a well-mixed soil sample, fill a bucket with 2 quarts of water (marked on inside of bucket).

Example of well-mixed soil sampleFiltering the soil sample

Pour in the soil, break any clumps with your fingers, and mix the soil suspension well for 15 seconds. Then let the sediments settle for 15 seconds. Pour the soil suspension through a #20 sieve (850 micron pores) over a #60 sieve (250 micron pores). SCN cysts are generally 470 to 790 microns long and 210 to 580 microns wide.

Rinse the debris caught on the top sieve with water, and then discard its contents. Carefully wash the cysts and accompanying sediments from the #60 sieve into a clean beaker or directly into a 100 ml plastic grinding tube using as little water as possible.

Procedure for automated cyst extraction (elutriator)
We have developed a custom, automated procedure for cyst extraction that we use to process large numbers of samples in the Tylka lab. With this method, we add 400 ml tap water to a graduated beaker. The volume is raised to 500 ml with soil, and the sample is allowed to sit for 15 minutes. Then we thoroughly stir the sample, and allow it to sit for another 15 minutes.

Soil sample

After resting, the soil/water mixture is added to the machine beakers and the volume raised to 1800 ml.

After resting, the soil/water mixture is added to the machine beakers and the volume raised to 1800 ml.

The valve to the air drills are opened and and allowed to stir for 15 seconds.

The valve to the air drills are opened and and allowed to stir for 15 seconds.

Then the sample is passed through a nested #20 sieve over a #60 sieve.

Then the sample is passed through a nested #20 sieve over a #60 sieve.  

We collect what is caught on the #60 sieve.

We collect what is caught on the #60 sieve.