UW Soybean Plant Health
SCN |
Disease Cycle |
Detecting SCN |
What is the HG type test? |
SCN-resistant soybean varieties |
Managing SCN |
SCN links |
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Figure 2. White female cyst nematodes and cyst on roots of soybean. Note much larger N-fixing root nodules. Click on image to view a larger version. Photo credit: Craig Grau. |
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Figure 3. Cysts are dead females containing eggs. |
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| Figure 1. The second stage larvae infect roots of soybean. |
At this stage, the nematode is too small to be seen with the naked eye, but it is able to penetrate soybean roots and cause the formation of specialized feeding cells in the root's vascular system. If the juvenile becomes a male, it leaves the root and moves through the soil and probably does not contribute further to plant damage. If the juvenile becomes a female, it remains in the roots and swells to a lemon-shape as it matures. Plant damage is mainly due to the feeding of females.
The mature females are barely visible, a white dot about the size of a period at the end of this sentence. Compare this to the size of a nitrogen-fixing nodule, which is much larger (Figure 2). The white females become yellow as they age and then brown after they die. The brown stage is the cyst for which the soybean cyst nematode is named. Each cyst contains hundreds of eggs, which are protected by the cyst (Figure 3).
The soybean cyst nematode is moved every way that soil moves: water, wind and farm equipment.
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Information from this site can be copied and distributed for educational use. Please credit the source with our name and URL: University of Wisconsin-Madison, Departments of Agronomy, Entomology, and Plant Pathology at www.plantpath.wisc.edu/soyhealth.
Last update 3/07