Industry representative: David Norman
HDC project cost: £33,349
Occasional samples received as part of STC Plant Clinic acquisitions have detected virus and viroid problems in lettuce but the scale of the infection is rarely determined. In UK asparagus crops (HDC 384/384a) two years screening work by STC found a number of important viruses even though all crops were asymptomatic. It is thought that such virus infections play a significant role in the phenomenon known as ‘asparagus decline’.
No survey of virus infection in UK field lettuce has been undertaken for a considerable time and therefore the potential impact of viruses such as LMV and BWYV is not known. A virus screening exercise similar to that proposed was carried out in Spain in 2001/2002. This study found Cucumber mosaic virus (CMV), Lettuce mosaic virus (LMV), Beet western yellows virus (BWYV) and Tomato spotted wilt virus (TSWV) all present in lettuce samples. In some instances multiple viruses were found in single samples. In addition to sampling lettuce crops the study screened associated natural vegetation such as nearby weeds and found them to be important reservoirs of infection (Moreno et al 2004)
The primary purpose of the project, therefore, is to carry out a systematic survey of UK field lettuce (and possibly weed species) over a one or two year period to determine the incidence, prevalence and significance of lettuce viruses.
1. Conduct a desk-study to review which viruses have previously been reported in UK and European leafy salad crops. Determine which lettuce viruses can be tested for efficiently and cost effectively using an ELISA based system and draw up a list of priority viruses for the project.
2. Gather geographically diverse lettuce plant samples over the 2014/2015 season, according to a standardised sampling protocol, and store as necessary prior to analysis. Gather information regarding the performance/quality of the crops sampled relative to expected performance/quality.
3. Screen samples for the viruses determined in Objective 1 using commercially available ELISA test kits.
4. Relate performance of crops to presence/absence of virus and communicate results to growers via the project report.
5. Communicate information regarding virus vectors and control of the vectors that transmit the viruses detected during the project. Prepare a Factsheet on Lettuce Viruses and their control.