The Unique Life Cycle of Soybean Cyst Nematode Makes it a $1.5 Billion Parasite

Soybean cyst nematode (SCN) is rated as the most important pathogen of soybean in the United States, causing approximately $1.5 billion in soybean loss every year. SCN was first discovered in NC state in 1954 but has now been found in all soybean-growing states in the U.S. Nearly every soybean fields in the U.S. has been infested with the expensive nematode.

For those who are not familiar with SCN, SCN is a parasitic roundworm that feeds on the roots of soybean plants, causing significant damage and yield loss every year worldwide.

The biology and lifecycle of SCN give it the capability to survive in the absence of soybean plants and thrive in the presnece of susceptibe soybean plants. This article is meant to decribe how the life cycle of SCN contributes to a high soybean loss and how growers can reduce or prevent the loss using an integrated pest managemnt approach.

SCN Life Cycle:

Life cycle of soybean cyst nematode. (a) eggs, (b) larvae, (c) larvae feeding, (d) dead females (cysts) filled with eggs, and (e) needle-like mouthpart of SCN.

The SCN has a unique life cycle in which the nematode burrow (enters) into the soybean root and feed, reproducing, and producing eggs within the root.

To enters the root, the nematode uses its needle-like mouthpart known as stylet and cell wall degrading enzymes to breakthrouth the cells. On entrying the cells, female SCN desolves the cell walls (peel off the outside coat) of several cells and uses its mouth to “juice out” and feed on the inner content of the cells. After about 2 to 3 weeks of feeding, the neamtode will reproduce and can become filled with up to 600 eggs that will hatch into new larvae that will continue to feed on the roots. Over time, the larvae matures into adult females, reproduce new sets of larvae or produce protective cysts that protect them from environmental conditions and pesticides.

Yield Loss: The feeding of SCN larvae on the roots of soybean plants disrupts the plant’s ability to absorb water and nutrients, leading to reduced plant growth, yellowing leaves, and ultimately reduced yields.

Prevention and Management: To reduce or prevent damage from SCN, farmers can implement an integrated pest management (IPM) program that includes a combination of cultural, biological, and chemical control methods. Some effective methods include:

  • Crop rotation with non-host crops, such as corn or wheat, to reduce the population of SCN in the soil.
  • Use of resistant soybean varieties that are less susceptible to damage from SCN.
  • Monitoring the soil and plants for signs of SCN infestation, such as yellowing leaves or stunted growth, and implementing appropriate control methods when necessary.
  • Implementing soil-fertility management practices, such as adjusting soil pH and maintaining soil health, to reduce the population of SCN.
  • Using nematicides or other chemical control methods as necessary, within an IPM program.

By implementing these methods, farmers can reduce the damage caused by SCN and protect their soybean yields.

Sources for additional information

Soybean cyst nematode disease​​​. https://www.apsnet.org/edcenter/resources/archive/Pages/SoyCystNema.aspx

How to manage the $1.5 billion soybean cyst nemat problem. https://www.agriculture.com/crops/crop-protection/how-to-manage-the-15-billion-soybean-cyst-nematode-problem

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