Soybean cyst nematode (Heterodera glycines)

Soybean cyst nematode: biology

When temperatures and moisture levels are adequate in the spring, worm-shaped SCN juveniles hatch from an egg into the soil. There are over 200 eggs per female, and eggs can survive more than 10 years dormant in the soil.

The soybean roots act as beacons for food to these young juvenile nematodes, which have no problem finding a point of entry and forming their feeding site inside the root. This feeding site, known as the syncytium, opens an entryway for other pathogens and increases the soybean plant's susceptibility to a number of soilborne pathogens, such as Pythium, Rhizoctonia, Phytophthora and Fusarium.

Soybean plants show slight to severe stunting with slight to severe chlorosis. Yield decline is gradual over several years. Nodulation is diminished, and the canopy is slow to close. Symptoms can be similar to those of nitrogen and/or potassium deficiency. Some root decay. Tiny cysts on roots first appear as white to yellow, lemon-shaped females on the root surface; then the cysts turn dark brown with age. These cysts are much smaller than the nitrogen nodules on the roots. Affected plants tend to develop in a circular or oval area in a field. If SCN are suspected, check roots for cysts.

In 2013, we began detecting SCN presence in Ontario. Findings are indicated on this interactive map.