How can you identify root-knot nematodes in landscape plant roots?

• A. Identify by leaf color alone.
• B. Only above-ground signs.
• C. Look for galls or knots on roots and poor plant performance; confirm with lab analysis if needed.
• D. Nematodes cannot be detected.

Answer: (C)

Root-knot nematode problems begin where the nematodes feed: the roots. They cause cells to swell and form galls or knots along the root system. When you inspect the roots, you often see these abnormal swellings, which are a telltale sign of nematode activity. The presence of galls, along with reduced plant vigor such as stunting, yellowing, or poor growth, points to nematode damage because above-ground symptoms can be caused by many other issues and aren’t specific. Since some galls can result from other problems and not all nematodes produce obvious root distortions, laboratory confirmation—by extracting and identifying nematodes from root or soil samples—helps verify the infestation. So, looking for galls or knots on the roots plus the associated decline in plant performance, with lab analysis if needed, is the best approach to identify root-knot nematodes in landscape plants.