Recommended List 2023

Provisionally Recommended varieties (PR) are tested for a minimum of three years before being added to the list in PR1. They are tested for a minimum of three further years before potential promotion to the fully Recommended (R) group. All varieties are issued with an automatic 1-year warning of removal from the list if their adjusted root yield values are below 100% of the controls. Varieties may be recommended for Specific Use (S) if they have specific attributes but are inferior to recommended varieties in other important characters (generally yield) and they justify limited use.  

Candidate varieties are usually tested using 1 to 2kg samples of seed supplied by breeders. Once a variety has been provisionally recommended for commercial use, its seed is drawn from the commercial bulks. The bold figures in the supplementary table indicate varieties that have been tested with commercial seed; usually 500 units or more. PR1 varieties have been tested using only breeders’ seed provided as 1 to 2kg samples. PR2 have been tested with commercial seed in the most recent test year but with breeder’s seed in the previous two. Similarly, PR3 have been tested with commercial seed in the most recent two seasons whilst only data for R varieties have come from trials using commercial seed in all three years. Where seed lots smaller than 500 units are supplied, these are classified as breeders’ seed. The data where all three years and the mean are in bold are most representative of the commercial situation.

The 2023 RL yield data are presented as a three-year mean of 16 trials  5 each in 2019 and 2020 and 6 in 2021 (in 2019 the very wet autumn meant that some sites were too wet to harvest, whilst in 2020 sites were lost owing to poor establishment).  

If selecting a range of 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.

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

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

The table shows data from the eight replicated trials (two in 2019 and three each in 2020 and 2021) that were untreated with foliar fungicides. These show the varietal performance under the natural cocktail of diseases. Rust and powdery mildew were the main diseases but others were present at low levels in some plots (including cercospora in 2020). These results should be treated with reserve as the data tends to be variable (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 3.3% are not statistically significant in the 2023 RL. In addition, growers need to consider that 'establishment' will vary between years (typically in the range 84 to 90%). 

Establishment figures in the tables are presented as % of controls. Since the 2013 trial season most seed has been sown at 6-9 cm seed spacing and thinned to produce an average population, for yield determination, of just over 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 number of seeds sown is not counted and the plant counts are carried out at the 2-4 leaf stage) it does indicate the small differences that can exist between recommended varieties and seed lots.

In 2020 Covid restrictions resulted in the trials being drilled to a stand and not gapped.

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) and 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 have an effect on 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 (devernalisation).

ESB figures can be generally classified as the genetic's tendency to bolt under bolting pressure. (NSB is recorded in the main RL trials which are drilled from mid to late March.) Later, Normal Sown Bolting (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 in their seed production by ensuring good isolation distances and closely aligned flowering and pollination timing but, inevitably, there may be some year-to-year differences in bolting within a variety.

Early sown bolting (ESB) trials are sown separately to the main RL trials and are drilled sequentially from the last week 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, some AYPR rhizomania strains have been identified at a few sites 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.  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 Contract Manager. BCN tolerance does not apply to free-living nematodes such as those causing Docking Disorder. The BCN tolerance breeding technology has been demonstrated, 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, 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 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 are able to 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 Area Manager.

The 2023 RL includes two varieties that are tolerant to specific ALS herbicides (Conviso).  The herbicides for use 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 expected 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 provided 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.  In the case of Maruscha KWS, this has partial tolerance to beet mild yellowing virus (as per the definition in the ‘Definitions of susceptibility to pathogens’ above). The breeder has further information on this and the other yellowing viruses.