Transmission of a strain of tomato black ring virus by Longidorus elongatus (Nematoda).

Longidorus elongatus (de Man) was always found in soil from patches in raspberry and strawberry plantations where the plants were infected with the beet ringspot (Scottish) strain of tomato black ring virus but rarely elsewhere in the same plantations. L. elongatus hand-picked from virus-containing field soil transmitted the virus to sugar beet, turnip, and spinach seedlings, but did so less often than might have been expected from the infectivity of the whole soil from which the nematodes came. Noninfective L. elongatus acquired and subsequently transmitted the virus from infected cucumber and potato plants. When hand-picked adult and larval L. elongatus were used separately, only larvae transmitted. Also, when infective soil was fractionated by sieving through meshes of successively smaller size, the infectivity of the fraction retained on each sieve, relative to the number of L. elongntus it contained, was greatest for samples containing the smallest larvae. 9 previously undescribed species of Longidorus, closely related to L. elongatus, was associated with an outbreak of the lettuce ringspot (English) strain of tomato black ring virus.