VIRUS YELLOWS PATHWAY
BBRO is working closely with British Sugar and the NFU Sugar Board to find long-term solutions to the challenge of Virus Yellows (VY).
Scroll down for more information on the 12 strands of research currently being undertaken and to access an overview of the industry's Virus Yellows Pathway.
VY Risk Forecasting
BBRO work closely with Rothamsted Research to assess the level of virus threat expected per year and the estimated arrival of M. persicae and Macrosiphum euphorbiae (the primary aphid vectors of virus yellows) into the sugar beet crop.
Once flight and risk is determined we work with British Sugar, several growers and agronomists to monitor aphids across the four sugar beet factory areas through the spring and early summer. The data received is fed into the BBRO aphid survey (Access the Aphid Survey Dashboard) and used to form guidance issued via our Advisory Bulletin and other communication outlets.
From the 3rd week in April until early July, approx. 45 sites are closely monitored, twice a week for green wingless aphids on 20 plants. In addition, at the BBRO managed sites, yellow water pans are also deployed, and samples taken twice a week for laboratory analysis to confirm numbers of winged M. persicae and Macrosiphum euphorbiae, the primary vectors of virus yellows.
Influential factors impacting aphid numbers in crops
In field crop monitoring
Monitoring sites include both CruiserSB and untreated crops. Winged and wingless aphid numbers are expected to increase throughout May and early June, especially on non-Cruiser treated crops. Where the threshold of one green wingless aphid per four plants (5 or more wingless aphids per 20 plants) is exceeded on the monitoring sites, growers with crops in the area are encouraged to check their own crops with some urgency and where required apply the appropriate foliar insecticide. In addition, in some crops, particularly with small plants present, the persistence of foliar insecticides can be relatively short, so growers are encouraged to continue monitoring and where available some may need to use all three allotted insecticides before the onset of mature plant resistance.
We would expect that Cruiser-treated crops would have effective protection from green wingless aphids for between 8-10 weeks post sowing.
The forecasting model is managed by Rothamsted Research.
Since the formal withdrawal of neonicotinoid seed treatments in 2018, BBRO has increased its efforts each year to find new solutions for Virus yellows. This includes a number of trials testing current and future RL varieties to assess their resistance levels to all 3 viruses that form Virus yellows (Beet chlorosis (BChV), Beet mild yellowing virus (BMYV) and Beet yellowing virus (BYV)). The data from these trials will undoubtedly further help with variety choices in the future and form part of IPM strategies for aphid and VY management.
‘Goliath’, our strategy for assessing varieties with specific trait claims for one or all of the yellowing viruses, remains our flagship trial for variety testing. We aim to test approx. 16 entries from KWS, DLF Beet Seed, Betaseed and Strube. The varieties are hand inoculated with one of the viruses, allowing us to look for virus resistance to one or all 3 of the viruses, alongside some untreated plots to monitor in-field variations/impacts on the crop.
The plots are carefully managed to reduce any threat of virus spread beyond the trial or the invasion by wild aphids which could skew the data.
Following two years of basic strip trials we are formalising our endophyte grass research. In 2022 we set up two sites with randomised plot trials which will be over-sown with sugar beet in 2023. The hope is that the beneficial impact of the endophyte (a fungus within the grass, which produces alkaloids to protect its host) can be transferred into the sugar beet. The areas at Morley in 2022 looked promising and certainly greener, but we need to send samples to New Zealand for analysis to confirm that the alkaloids made it into the sugar beet. If successful, we will optimise this approach to minimise competition for resources from the grass. One option could be to substitute the living grass for hay or grass-seed meal from which the alkaloids can leach out and be taken up by the sugar beet.
Photo: Aerial shot from the BBRO drone clearly showing the effect of endophyte grass. This remained evident in the crop through to harvest.
BBRO work has clearly shown that cover crops ahead of sugar beet can have a positive impact on soils properties, helping to improve soil structure, soil biology, organic matter and nutrition. These effects are frequently translated into improved sugar beet yields.
Currently awaiting results.
PhD student Suzannah Cobb investigates virus isolates on behalf of BBRO to read the latest info on her project please click here.
