Tests for transmission of cherry leaf roll virus using Longidorus, Paralongidorus and Xiphinema nematodes

Abstract

SUMMARYThe ability of 10 nematode species to transmit three strains of cherry leaf roll virus (CLRV) was tested by three methods: (1) virus‐infected source plants and virus‐free bait plants were grown concurrently in nematode‐infested soil, (2) as for (1) but virus source plants were removed before bait plants were planted, and (3) nematodes were extracted from soil after access to virus source plants, and were added to pots containing bait plants. The occurrence of galls on roots showed that nematodes fed both on source and on bait plants in all experiments and, in some experiments, CLRV was detected by direct assays (slash tests) of Longidorus elongatus, L. leptocephalus and Paralongidorus maximus. Although the nematodes readily transmitted control viruses, for which they are known to be vectors, CLRV was detected by root assays in only a few bait plants exposed to L. elongatus, L. macrosoma, Xiphinema diversicaudatum or L. leptocephalus + X. vuittenezi in tests by method 1. The recovery of CLRV in these tests is interpreted as being due to contamination.These results add to the increasing circumstantial evidence against the involvement of nematodes in the transmission of CLRV. Other possible mechanisms of spread are discussed.