Nematodes are tiny roundworms belonging to one of the most species-rich animal phyla, with more than 20,000 species. Some species, such as the stem nematode (Ditylenchus dipsaci), can produce tissue distortions and hence galls through toxic components of their saliva that break down the middle lamellae between plant cells. They are regarded as pests of crops such as potatoes, sugar beet and tobacco.

Back to Glossary Back to Term