It is hard to see the damage that has been done to plants caused by nematodes. The most common damage is shorter roots, which causes slow growth, and yellowing of the leaves of the plants. Usually the plant damage done by nematodes goes unnoticed because there are no specific symptoms that are associated with nematode damage and is usually put off as a nutritional disorder. If these types of symptoms occur, instead of using a pesticide or other chemicals, have your soil tested for nematodes to save you time and money. Root Knot Nematodes do the most damage to the plants root system because they feed on the root cells rather than the liquids that the roots produce for the plants like the Lance or Sting Nematodes. However, if there is an infestation of a Lance or Sting nematode, the roots may appear to be rotting or dead.