NIAB salads open day: Speciality lettuce varieties on trial

There were plenty of new lettuces on show at the NIAB salads open day earlier this month. Ian Gillott reports.

The National Institute of Agricultural Botany (NIAB) salads open day was held on 3 July at Flanders Farm, Shippea Hill, Cambridgeshire, courtesy of JB Shropshire & Sons.

The task of organising and executing the trial was carried out by NIAB vegetable specialist Bruce Napier, who has taken over from Mike Day. Day, who was responsible for previous salad trials, retired from full-time employment at NIAB earlier this year. He continues to work as a consultant and was on hand at Shippea Hill to give advice and support.

Most varieties were sown on 18 April and planted out on 14 May. The Little Gem was sown on 25 April and planted out on 19 May. The lettuce blocks were supplied free of charge by Delfland Nurseries of March, Cambridgeshire.

Napier says the trial included more speciality varieties than in previous years, possibly reflecting the interest on the Batavia types in particular. He also remarked on how delighted he was that the trial had been supported so enthusiastically by the seed companies.

Nunhems Seeds, of King's Lynn, Norfolk, has a new summer Iceberg in Gondar (Nun0120) - a medium to large lettuce. It is relatively slow-growing with strong resistance to bolting and tipburn, as well as having resistance to downy mildew races 1-26.

Nunhems lettuce specialist Richard Pett says this variety stood up particularly well in the heat of summer 2006. A new midi-Romaine variety, Cuore, produced plants for the summer period with well-blanched leaves and has been introduced for the hearts market.

Although not in the actual trial, Nunhems has high hopes for its new Romaine Nun6507 - a variety that can be used throughout the UK season and has done very well in trials in the Spanish season. The variety has Nasonovia resistance as well as Bl 1-26.

Shamrock Seed Company, whose UK office is in Boston, Lincolnshire, was showing a new Iceberg Holywood which, according to representative Mark Digby, is a result of a mixture of American and European breeding. Its recommended harvest runs from just after the longest day of the year into October. It is slightly smaller that other varieties that emanate from the US. It has 1-25 mildew resistance combined with a very short core and good holding ability. Shamrock also had two attractive red lettuces in the trial. The first was a Red Batavia, Blackhawk, which has good field tolerance to mildew. It produces a 300-400g head and is largely aimed at the processing market. The other red variety is Stealth - a very heavy, triple-red, oak leaf with very good internal colour. The breeding of this variety possibly indicates a trend for the future as, when planted at close spacing, it could be mechanically harvested. For growers who require something different, Shamrock was showing its Red Deer's Tongue variety, Relic.

Clause UK of Market Rasen, Lincolnshire, has always had a reputation for producing some excellent Scarole varieties. This year it has come up with a new Scarole, Maruchka. This follows on from the very successful and reliable variety, Kalinka. Maruchka is suitable for late spring to early autumn and, as Clause representative John Ward points out, has a very erect habit for ease of harvesting. The uniform, well-balanced leaves make it ideal for processing.

Clause also has Alexia, a semi-erect Geante-maraichere type for summer to early-autumn harvesting. This has narrow leaves that produce a high commercial yield. A variety bred with mechanical harvesting in mind is Emily, a coarse frisee that can be used for the summer period. It is particularly uniform, upright and bolting tolerant.

Nickerson Zwaan, based in Market Rasen, Lincolnshire, has a new Iceberg - Musson. This is a slow-growing, large-heading variety that is Nasonovia resistant and has a mildew resistance of 1-26. It is very slow-filling, which enables it to have a large harvest window. Sometimes Iceberg can have a slightly bitter taste but Musson is sweet and is a variety that would appear to be suitable for both processing and pre-pack.

Another slow-growing variety from Nickerson Zwaan is Antartica. It is a medium to large lettuce that, again, is slow-filling and provides a wide harvest window. Flat ribs give less damage during the sensitive autumn period and it has Bl 1-26.

The interest in Batavia types continues to increase and much of this interest can be attributed to food writers who eulogise about the taste of this type of lettuce. Bred by Vilmorin, the as-yet-unnamed BVP 30173 has excellent resistance to both downy mildew and Nasonovia because French growers cannot use imidacloprid on lettuce. Being open-hearted, it is ideally suited for processing and it tastes good.

Enza Zaden, an international seed breeder that has facilities in Evesham, Worcestershire, has gained a reputation for producing reliable varieties of Little Gem. Coventry and Maureen have become popular varieties over the past few years and now Enza has introduced a new variety, Stretham (E16.6592), which has full mildew resistance. It is very similar in size and shape to Coventry and is claimed to be slow-bolting.

E16.9621 and E16.8896 are two new Romaine varieties which are Nasonovia resistant and have already performed very well in Spain. Both have Bl 1-26 mildew resistance and are suitable for hearts production. Ametist is one of the new range of Enza Icebergs which has Nasonovia resistance, as well as the full mildew package. It is suitable for early-season production.

Rijk Zwaan, which has offices in York, was instrumental in introducing Nasonovia-resistant varieties into the marketplace. Since this first introduction, it has continued to develop new varieties that offer this type of resistance. The latest one it has introduced is Albanas RZ, which is suitable for both spring and autumn production. It has Bl 1-26 mildew resistance. In some areas of Europe, resistance to Nasonovia has been discovered but, according to Rijk Zwaan lettuce specialist Gerard Van de Hut, this has not yet been seen in the UK. With the disappearance of so many insecticides, growers have come to rely heavily on Nasonovia-resistant varieties, especially at certain times of the year when the insect pressure is high.

Surrey-based Tozer Seeds continues to be innovative in introducing a number of speciality lettuce varieties. The salad-pack industry places a much greater emphasis is on flavour than it has done in the past. The breeders at Tozer have come up with some varieties that have both an attractive appearance and a good flavour.

Tozer representative Nick Forsyth showed a very attractive, sweet-flavoured processing endive, TZP 0338, at the trial - together with a Red Oak leaf TZ 2584, which has very glossy, deep-red leaves with good mildew resistance. This is partnered with Tozer's Green Oak leaf variety, TZ 5045 - a striking lime-green colour with a thick, frilly leaf structure and good bolting resistance.

Although Iceberg and Romaine lettuce remain the backbone of the lettuce growers' programme, several newer types are being introduced that are of special interest to the processor and salad-pack producer.

Nigel Kingston, of Syngenta, demonstrated the versatility of the company's BellaGio range of lettuce varieties. The main attraction of this type of product is undoubtedly its convenience. Once cut at the base, it is ready to eat. Especially suited to salad packs, the variety combines a high percentage of usable product with a minimum of waste.

There were several BellaGio types in the NIAB trial. Robinio is the market-leading red type in one-cut lettuce. It is a cherry-red colour with Bl 1-24 and Nasonovia resistance. Curletta is a blond, wavy-leafed variety, which has a good shelf life and also has Bl 1-24 and Nasonovia resistance.


There were two main talking points that seemed to impress those attending the NIAB trial: firstly, the skill of the plant breeders for producing so many new and attractive products and staying ahead of the game where resistance to mildew and Nasonovia was concerned; and secondly, a general consensus of opinion that NIAB had skillfully managed to show so many varieties when they were at their best - not an easy feat when taking into account some of the extreme weather conditions the trial site had experienced this spring.

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