Potato Review

38 POTATO REVIEW JANUARY/FEBRUARY 2020 VIRUS Integrated pest management Achieving low virus and vector pressure within UK potato-growing areas will require an industry wide integrated pest management (IPM) approach to virus control. This includes adequate segregation of ware and carrot crops and seed fields, ware growers sourcing the cleanest input seed and adequate control of volunteers to reduce the virus reservoir. Varieties could also play a useful role, with some more tolerant to viruses than others, but this is an area that requires more targeted research to make an impact in the field. Currently, National List (NL) trials aren’t using the dominant strains of mosaic virus to test varieties as they come through the system, so published information is not relevant to what is happening at farm level. “Like with PCN, we need further knowledge on the tolerance and resistance status of potato varieties to the most prevalent virus species and more trials using the right inoculum, like with late blight. “To minimize the impact of virus and aphid- borne infections, planting varieties resistant to PVY should be an important option in areas of known high virus and aphid pressure.” Targeted control Nick Badger, Potato Portfolio Manager at Certis, which recently launched its Tubercare initiative to promote seed tuber health through the production chain, agrees these IPM measures will be increasingly important as chemical options for vector control dwindle. News that foliar insecticide Biscaya (thiacloprid) will be withdrawn in 2020 will largely restrict potato growers to just two insecticides unaffected by resistance in important aphid species by 2021. These are Insyst (acetamiprid) and Movento (spirotetramat), although the latter has the label restriction: ‘Applications in potato varieties that produce flowers can only be made from the end of flowering (BBCH 69)’. Other options include pyrethroids – although the insecticide group offers limited efficacy against a range of PVY vectors – and mineral oils, which have been shown by recent AHDB work to improve control of potyviruses when used as part of a wider programme. “It means growers will have to be much more targeted in how they use these available products to optimise vector control,” said Nick. • Mosaic virus levels on the rise in UK and European seed • Ware growers should ask for a virus test when sourcing seed • Changes in SPCS needed to stop problem getting worse • Further knowledge of varieties’ virus tolerance and resistance needed • Most prevalent and difficult to detect virus is PVYNTN • IPM key to reducing virus and vector pressure as insecticides go Virus pressure – key points PVY K Edward Certis Potato Product Manager Nick Badger