Staining and counting SCN eggs


After extracting the eggs from the cysts  in the prepared soil sample, place 4 to 5 drops of 1 M HCl and approximately one eye-dropper full of acid fuchsin stain into each beaker of egg solution. Heat beakers containing eggs and stain in the microwave until the suspension is about to boil (approximately 3 minutes for 12 samples). Remove beakers from microwave and allow to cool. Place beakers in the refrigerator until they are counted.

To prepare the acid fuchsin stain
Add 3.5 g acid fuchsin and 250 ml glacial acetic acid to 750 ml distilled water. Stir well.

Counting eggs
Increase the volume of liquid in a sample to 100 ml with tap water. Examine the empty counting slide under the microscope to be certain that there are no eggs remaining in the slide from previous counts.

Thoroughly mix the sample, and immediately draw a sufficient volume of the suspension into a glass pasteur pipet to fill the counting slide. Fill the counting slide from the pipet.

A nematode counting slideStained SCN eggs viewed under the microscope

Systematically move from cell to cell in the slide grid, counting all SCN eggs. Record the total count and the dilution. Pour the liquid from the slide back into the sample, and rinse the slide thoroughly with a water bottle.

Source for nematode counting slides:
Chalex Corporation
5004 228th Avenue S.E.
Issaquah, Washington 98029
(425) 391-1169.

Source for chemicals:
Fisher Scientific
1600 W. Glenlake Avenue
Itasca, IL 60143
(800) 932-5000