Data from the last three years of trials is used when producing the RL list and these are shown in the three-year datasets in the supplementary table. In most cases there are relatively small differences in yield performance between years but as consistency of performance is an important factor when selecting varieties, these datasets allow the user to look at variation of any listed variety’s performance over the three years.

There is no evidence from these trials to indicate that any recommended varieties show any response to later lifting or greater frost tolerance.   

Provisionally Recommended varieties (Y) are tested for a minimum of three years before being added to the RL list in Y1. Varieties may be recommended for Specific Use (SY) if they have specific attribute(s), but are potentially inferior to recommended varieties in other important characters such as yield.

Candidate varieties are usually tested using one to two kg samples of seed supplied by breeders. Once a variety has been provisionally recommended for commercial use, its seed is drawn from the commercial bulks, usually 500 units or more. Y2 have been tested with commercial seed in the most recent test year but with breeder’s seed in the previous two. Similarly, Y3 entries have been tested with commercial seed in the most recent two seasons whilst only data for Y4, Y5 etc varieties have come from trials using commercial seed in all three years. 

The 2027 RL yield data is represented as a three-year mean of 20 trials; four in 2025, seven in 2024, nine in 2023.

If selecting several varieties it may be beneficial to make selections of material from different genetic backgrounds and the listing of Breeders and their UK agents is intended as an aid for this selection.

Variety susceptibility to disease was determined in both the main yield trials and untreated trials (no foliar fungicides were applied). The current foliar disease data do not indicate tolerance or resistance, but simply the level of leaf infection. The data in the RL table are ratings whilst those in the supplementary table are recorded as percentage leaf infection.

Data from the untreated yield and disease trials (no foliar fungicide treatment applied)

The table shows data from the four replicated trials (one in 2025, one in 2024, two in 2023) and that were untreated with foliar fungicides. These show the varietal performance under the natural cocktail of diseases that develop in any one particular season. Rust, powdery mildew and cercospora were the main diseases but others (such as ramularia) were present at low levels in some plots. Rust data is often the most robust but all results should be treated with reserve as data can be variable within and between years and sites (see three-year data table).  

Growers can use the establishment figures when calculating the seed rate required to produce their target plant population. In practice, the differences recorded between current varieties in trials are relatively small and those less than 4.4% are not statistically significant in the 2027 RL. In addition, growers need to consider that 'establishment' will vary between years and again influenced by season and other local factors such as soil pests (typically in the range 85 to 95%). 

Establishment figures are presented as % of the controls in the tables. Where trials had been gapped the seed has been sown at 6-9 cm seed spacing and thinned to produce an average population, for yield determination, of approximately 100,000 plants per hectare. Pre-thinning plant counts are used to determine the establishment figures. Whilst this is not a true record of establishment (as the number of seeds sown is not counted and the plant counts are carried out at the 2-4 leaf stage) it does indicate that small differences can exist between recommended varieties and their seed lots.

Sugar beet is a biennial plant that will only become reproductive (i.e. produce a flower, or as it is usually referred to in beet “a bolter”) once it has been exposed to low, vernalising temperatures (for bolting) followed by long days (for seed production).  Temperatures between 3 and 12°C are the critical temperatures for vernalisation, with temperatures in the mid-range having greatest effect and those towards 12°C the least. As a rule-of-thumb around 40 days of vernalisation (where temperatures during the 24 hours are within this range) are required for beet to bolt. Vernalisation can start before the beet emerge, therefore depth of drilling can influence bolting.  Other factors such as field location (north or south region of the beet growing area, by the sea or inland, sheltered by woods or buildings, sloping topography and orientation of field) can also affect the temperatures experienced by beet, and hence vernalisation.  In some instances, high temperatures immediately after a cool vernalising day can neutralise this physiological change (i.e. devernalisation). In some seasons dry or other stress(es) can increase bolting levels.

Early sown bolting (ESB) figures can be generally classified as the tendency of any genetic to bolt under such pressure. Normal sown bolters (NSB) are  recorded in the main RL trials which are drilled from mid to late March. NSB is often classified as production bolters or contaminants where another source of pollen has pollinated the female plant.  Plant breeders take care to minimise this risk in their seed production by ensuring good isolation distances and closely aligned flowering and pollination timings but, inevitably, there may be some year-to-year differences in bolting within a variety.

ESB trials are sown separately to the main RL trials and are drilled sequentially from the middle of February to the 5th March. The ESB figures are the number of bolters recorded from these earlier sowings for the last three years and should be used as a guide to compare varieties by growers sowing early and / or where high vernalisation (periods of cold) is expected.

ESB and NSB figures are quoted as number per hectare based on beet populations of 100,000/ha.  

Since 2007, more aggressive strains of  rhizomania have been identified (e.g. AYPR) at a few sites in East Anglia which continue to be monitored and breeders have developed varieties with enhanced resistance genes to the AYPR strains found at these sites. Yields of the AYPR varieties are determined in the normal RL trials, which are carried out in non-infested situations.  Glasshouse studies, using soil collected from AYPR-infected sites, are used to determine their effectiveness at reducing the build-up of this virus.  Roots of these varieties are tested for the presence of the virus using established diagnostic methods. AYPR approved varieties should be used where this strain is present – but consult BBRO/your BS Contract Manager/seed breeder for advice on managing this strain of rhizomania.

Beet cyst nematode (BCN) tolerant varieties are listed for use under BCN infested conditions but have yields suitable for use in non-infested fields. However, before selecting a BCN tolerant variety for non-affected situations it is suggested growers discuss this with BBRO and/or their British Sugar Account  Manager. BCN tolerant varieties on the RL have been shown in tests to have a pf/pi ratio of approximately 2.  Pi is the initial BCN population at the start of the season and pf the final population in the autumn at harvest. BCN tolerance does not apply to free-living nematodes such as those causing Docking Disorder. The BCN tolerance breeding technology has been demonstrated by the BBRO, in independent testing in the UK and mainland Europe, to give yield benefits under BCN infested conditions. The RL List is not indicative of the performance of BCN varieties under nematode infestation but yields are those determined in the normal RL trials, which are carried out in non-infested situations. With tighter rotations and climate change, BCN could be an increasing problem in some beet crops but generally this problem remains patchy within fields. It should be remembered that oilseed rape and many other brassica crops (such as those potentially in game/cover crop mixes) act as good hosts for BCN too, and rotation remains a key control method.

Based upon breeders’ submissions the BCN varieties could be listed as resistant, tolerant or light tolerant to BCN infection. Only tolerant types are currently listed and marketed. These types can produce higher yields than conventional varieties under these conditions and cause lower multiplication of the nematode population compared to conventional varieties.

The interaction of these varieties with the pest, and multiplication of BCN are complex issues influenced by a number of interrelated factors including starting population, cyst viability, sugar content, drilling date, soil type and weather. Breeders have their own information on the use of BCN varieties, as does BBRO. If you require further guidance or advice discuss with the specific breeder, BBRO or British Sugar Account Manager.

The 2027 RL includes six varieties that are tolerant to specific ALS herbicides (Conviso) and two with an added and stacked BCN trait.  The herbicides used with these varieties were approved by HSE in March 2019 and were available for the 2020 growing season. In the RL trials these varieties were treated with conventional herbicides. It is believed that they will have higher yields when treated with the ALS rather than conventional herbicides. More details of use of these varieties, including performance when treated with ALS herbicides, are available from the breeders.

Impurities of the beet from each yield plot are measured in the tarehouse at Wissington at the same time as sugar content.  The measurements use the current industry standard systems used for the commercial crop. 

These data are available from the BBRO for information but at present there is no significant difference in impurities between the RL varieties.

Tolerance to any of the three yellowing viruses is not assessed in the RL trials; the decision on whether to list a such a variety is based on breeder’s claims which are confirmed by the Crop Committee’s Expert Panel. Please speak to the breeder for further info.