ABSTRACT
Trichodorid species first received wide attention in 1951 by the discovery of their plant pathogenic role. Christie and Perry demonstrated that a species now known as Paratrichodorus minor. Interest in the group has increased since the early 1960s, when trichodorid species were discovered to be vectors of the plant viruses: tobacco rattle virus and pea early browning virus. Then Siddiqi erected a new genus Paratrichodorus for a number of species in Trichodorus, and divided the new genus Paratrichodorus into three subgenera: Paratrichodorus, Atlantadorus, and Nanidorus. Trichodorid species in general are root ectoparasites, usually aggregating at the root tip. One to three ventromedian precloacal supplements, exceptionally four; usually two supplements present within caudal alae region, third supplement less developed, anterior to caudal alae; or some species with only one supplement present. The symptoms it produced on host plants were abnormally stunted roots, a condition descriptively called “stubby root.”.
