The National Institute of Agricultural Botany (NIAB) onion sets trials annually highlight the best of what breeding companies and suppliers have to offer, while independently assessing performance across the board in order for UK growers to make the best of their crop and the season.
Early-maturing varieties open up the biggest opportunities for growers - both in increased yield and extension of the supply season - and the trials, held in Moulton, Lincolnshire and funded by HDC and participating seed companies, have a strong focus on identifying early performers.
In 2007 the English Set Company (ESC) introduced Red Emperor, a red option for the early market, reaching maturity soon after brown-skinned types. This red trend continues in 2008 with the Elsoms/Bejo introduction of Reddawn, which has proved to be even earlier than Red Emperor - ready for harvest alongside the brown types.
NIAB vegetable specialist Bruce Napier has been impressed with its results. He tells Grower: "The normal planting time for red varieties is mid-March, but Reddawn was planted at the same time as the browns in mid-February and is already maturing two to three weeks earlier than other early reds in the trials. This is the first year Reddawn has been trialled but it is proving very positive against the current market leader, Red Baron, from ABS.
"The Red Emperor submissions from ESC and ABS also look promising. It was hit with disease problems when first trialled last year but for two companies to enter it into the trials for 2008 means it is sure to be an important variety for commercial production - it is all about growing it right to ensure a healthy crop, and the suppliers can advise on how to do that. My gut feeling is it's a very good onion, but I'm not sure if its thick canopy will appeal to growers."
Allium & Brassica Supplies manager Jim West has also been pleased with results: "The trials are looking good this year and are offering growers the opportunity to compare what is available to them in an unbiased, independent showcase. Mildew has popped up again on one or two varieties but is nothing in comparison to last year. The trials are showing that early-season supply opportunities are increasingly available to growers."
Napier says an increased interest in production from sets is evident in the highest level of entries to the trials so far - 16 brown varieties and nine red types. And he says now is the time for UK growers to get on board and make the most of the opportunities: "Traditionally, sets come from Holland but the scale of production in relation to available land means the Dutch are running out of space to deal with required crop rotations to ensure clean, disease-free produce. UK growers are at an advantage as it is easier to find new growing sites with clean soil. Identifying early-maturing varieties also helps and allows growers to extend their supply season and reduce processors' reliance on New Zealand imports by a week each year. Reddawn looks set to provide that same opportunity in the reds."
Napier and his colleague, semi-retired NIAB vegetable specialist Mike Day, have witnessed a broad range of maturities across the trials this year, but note that generally crops have been earlier than last year. Last year's trials were slowed by wet and mild conditions - the crops put on extra leaves rather than bulk up their bulbs. Crops were also badly infected with mildew, with whole sections wiped out. Conditions have proved better this year and mildew has not been a big problem. While timings may vary slightly around the country, Napier says the trials represent the UK crop on a small scale and says 2008 is proving a good year for onion production.
Elsoms crop manager John Constable says: "These trials are an opportunity for us to show our product to the industry and show how it performs in the field. The trials are a great way of communicating the latest crop developments."
For the second year running, ABS101 (ABS) proved to be the fastest-maturing variety, ready seven to 10 days earlier than Forum (ELS), the previous earliest variety in the trials. This was closely followed by VCS 6003 (ESC).
Napier says that while these lines may increase in popularity, market leader Sturon (ESC) and Sturon types including Rumba (ABS), Setton (ABS) and Stur BC20 (ELS), with their above-average yields, uniform bulbs and storage capabilities, continue to remain firm favourites with growers - but those looking to supply the processed market should be looking for something a little bigger.
He says: "Half a dozen Sturon types entered into the trials is testament to fact that they are a good commercial option for growers. Retailers are looking for a product 40-60mm in diameter - Sturon is ideal for that market. However, if you are looking to create opportunities in process supply, Yagro's bigger bulb (60-80mm) is ideal for that market."
With continued restrictions on pesticide use and reduced product options, a new focus for onion varieties is that of erect foliage and thin crowns. Napier says erect varieties with no leaf cranking (doubling over of leaves) allow for easier mechanical removal of weeds: "The thinner the crown and more erect the foliage, the easier it is to get among the plants and weed by hand. It's not the main focus of the trials by any means, but moving into the future of reduced herbicide options and increased tolerance to existing products could become an important factor in crop selection."
The need for herbicides means current set offerings remain unsuitable for organic production - but looking ahead Napier sees opportunities for untreated set production coming out of seed produce. He explains: "Two strongly disease-resistant varieties for use in seeded onion programmes have not really caught on in the market but I know one of these, Santero - from the Nickson's Breeding Programme - is being added to the ESC sets catalogue for next year. It is likely the other, Elsom's BGS237, will follow as a late set option for organic production."
NIAB SET ONION PLOT DEMONSTRATION
Grower: Robert Oldershaw
Location: St Lamberts Farm, Moulton, Lincolnshire
Soil Type: Silt-land
Planted: 13 February 2008 (including Reddawn); lates (heat-treated) 19 March 2008
Rows per plot: Five
Row spacing: 25cm
Set spacing: 6.85cm (approximately)
ORGANIC ONION TRIALS 2006
Organic onions can be difficult to grow well, with weed competition and downy mildew as major threats. Seven varieties are listed as organic seed and six as organic sets on www.organicxseeds.com.
Rumba, Jet Set and Centurion were most vigorous and established; Drago and Setton were slowest to establish. Downy mildew was first observed on 29 June and by 7 July all plots had some infection. Due to the hot dry July, infection levels did not increase after this date. Hot-water treatment of the sets made no difference to marketable yield or mildew infection. Rots were the main reason for unmarketablity (mean 13 per cent) with two of the Sturon stocks being especially bad.
Varieties trialled: Source
Stur BC 20: Broer/ELS
Red Baron (heat-treated): Broer/ELS
Hyred (heat-treated): Broer/ELS
Red Emperor (heat-treated): ABS
ABS404 (heat-treated): ABS
Red Baron (heat-treated): ABS
Kamal (heat-treated): ESC
Red Emperor (heat-treated): ESC
Romy (heat-treated): ESC
Broer/ELS = Elsoms; ABS = Allium & Brassica Supplies; ESC = English Set