The appearance of a patch or patches of diseased plants in a crop is often the first indication of the existence of nematode–borne virus infection in the field. Ectoparasitic nematodes in the genera Longidorus, Paratrichodorus, Trichodorus and Xiphinema are involved in the transmission of nepo- and tobra-group of viruses. These viruses are also mechanically transmissible through infected sap. Infection of a bait plant is the standard method used for detecting nematode transmission in a test soil. Plants are grown in the soil to allow any viruliferous nematodes to feed and transmit the virus. Sap extracted from roots and leaves of the bait plants are then inoculated mechanically with a range of indicator hosts to confirm and identify the associated virus.
- Virus transmission