Nematodes, also known as eelworms or roundworms, have a slender, elongated body, usually tapered at both the head and tail. When fully grown, most species of nematode are less than 1mm in length. Nematodes are found throughout the world, in virtually every habitat in which there is a source of energy to sustain them. They are found in the sea, in fresh water and in the soil. They are found in extreme environments on the tops of mountains, in polar regions, as well as in more productive temperate and tropical zones. As well as free-living species, many nematodes are parasites, and will attack virtually all groups of plants and animals. They are also capable of transmitting pathogens between suitable hosts.

At SASA, the Nematology Lab is concerned with those species of nematodes that cause serious economic damage to plants. Often injury is caused by nematodes feeding on roots, interfering with water and nutrient absorption. Some nematodes burrow through plant tissue causing cell destruction. Secondary infection by other pathogens, particularly bacterial and fungal rots, may follow. Nematodes may also be highly efficient vectors of plant viruses, e.g. nematodes of the genus Trichodorus, which can transmit Tobacco Rattle Virus, a causative agent of spraing in potatoes.