The NIAB Salads Open Day, held in Cambridgeshire at the end of June, once again demonstrated the almost bewildering range of products available to the salad grower.
Plant breeders have been particularly successful at keeping pace with the latest races of downy mildew and incorporating the latest resistances into the new varieties they produce. However, there are many other qualities that growers are hoping to see incorporated into new salad varieties.
The processors of leafy salads, for example, are especially interested in leaf strength, which determines the shelf life of the packed product. Likewise, wholehead producers are anxious that an iceberg lettuce has good holding ability in the field. Other considerations include resistance to the lettuce-currant aphid and the ability of the crop to withstand tip burn, particularly important in Romaine lettuce.
Growers visiting the trial site in Cambridgeshire had the opportunity of inspecting 80 variety plots, which included romaine, little gem, batavia, leaf lettuce and endive in addition to iceberg lettuce.
Although sales of Iceberg lettuce have peaked, largely due to preferences towards little gem and romaine, it still retains its position as the mainstay of the salad industry. There were several new introductions on view at the trial.
Nickerson Zwaan already has an established market in Iceberg with its varieties Antartica and Kirkenia. Both of these are main season varieties that are slow-growing and have good field-holding ability. The best harvest date for these two varieties is from mid June until the end of September.
A new introduction, slightly faster growing than Nickerson Zwaan's two recently established icebergs, is Shetlandia. This is a compact and uniform variety with very good tipburn tolerance and holding ability with an excellence base, making for ease of cutting. Another new variety, Cornwalia, is available for trials.
Seminis has introduced Affic, an excellent, well-wrapped lettuce, which has a medium to large frame size and is quick to fill. It is also suitable for processing.
It has recently named its new dual-purpose iceberg Bombastic. This lettuce has been in trials for three years. It is slower that the existing and highly popular variety Stallion and has a slightly larger head size. It is claimed to have good holding ability. Boomerang, another recent introduction, is three days slower than Stallion and, like Bombastic, is comparatively slow to fill - enabling it to have a long harvest season. Both of these varieties have neat, tidy bases, which facilitate easy cutting.
A variety that has proved successful on the moss soils in Lancashire is Flight - a compact, fast-growing variety, which does not get too large on organic soil types. Flight can be grown both early and late and is very suitable for production under fleece or polythene.
Enza Zaden has a new numbered iceberg, 14.1393 - a medium-sized iceberg with a good shape and heart-fill. Like many of the other new iceberg introductions, this variety has Bremia resistance BL 1-27.
Little gem continues to be in demand and Enza has added two introductions to its already highly successful range. Westham is a dark green, medium-sized gem suitable for summer production. A rather lighter shade of green is represented by the variety Amible. This is a very versatile all-season gem. Both these new varieties have BL 1-27 mildew and Nasonovia resistance.
Nickerson Zwaan has a slightly taller Little Gem named Cucaracha, which has enhanced disease resistance with BL 1-27 mildew resistance and is also resistant to Nasonovia. Like Nicker- son Zwaan's iceberg varieties, the new introductions are the result of the breeding work carried out by Vilmorin.
A halfway stage between a little gem and a romaine is the mini cos. Elsoms has Tropicas, an attractive mini cos with excellent internal structure. A feature of this variety is its short core - and with its well-filled hearts of upright leaves it makes an ideal variety for leaf separation during processing. Another Elsoms mini cos, Ticcos, is also an ideal variety for processing.
Syngenta has a new midi romaine. Quite where the specification between a mini and a midi romaine begins and ends, I am not quite sure. However, Syngenta's variety is suitable for both whole head production and for processing. With a very good internal blanch, it is reported to have an excellent flavour. Syngenta also has a midi-red romaine with very dark outer leaves, with the inner green leaves giving a good contrast in colour.
Although batavia types do not lend themselves to pre-packing as well as with some other types of lettuce, there can be no argument that their flavour is outstanding. Syngenta has two representatives in this category, Funride and Cetero. Funride is the more compact of the two and is suitable for whole season production. It also has BL 1-27 Bremia resistance. Cetero is an intermediate type suitable for spring and autumn.
Nickerson Zwaan has Lirice - an open-hearted, thick-leaved variety suitable for both whole head and processing. The variety is very lobed and is slow to heart, giving it good holding ability.
There were some very attractive speciality lettuces on show at the trial. Tozer Seeds had a very deep-coloured red-leaf lettuce on show, TZ 9194, which has a high leaf count making it suitable for processing. It also had a baby leaf green variety with an erect leaf and excellent texture. With a narrow petiole and good to excellent field resistance to mildew, this variety looked particularly attractive.
Nickerson Zwaan had a red Apollo type Mazurosso, which looked an ideal candidate for bagged salad production largely due to the amount of good, strong, processable leaves. It also had a new triple red Lollo Rossa variety, LOL 9666, which is slow to heart and has good weight.
Syngenta had two new oak leaf varieties on show. A new red variety, LS 7994, is a triple red oak leaf with a contrasting green lower leaf.
LS 2993 is its new compact green oak leaf.
Clause continues to improve its range of endives. Daisy is a new introduction for spring, summer and autumn. A possible successor to Glory, it is not as fine but can achieve a better weight before breakdown occurs and in addition, has improved tolerance to bolting and tipburn.
A new medium coarse frisee is Ophely (previously clx 1161). This is a summer and autumn variety with good field-holding qualities. It also has improved tolerance to tipburn, with a good processing blanch.
Finally Magaly, formally clx 1183, is an Emily type for summer and autumn production. It is darker green than Emily, as well as being more compact with slightly thicker leaves.
The main sowing of most plots took place on 26 April and planting took place on 20 May. The second sowing (little gems) took place on 29 April with planting taking place on 20 May.
The trial, held at Flanders Farm, Shippea Hill, was by courtesy of JB Shropshire & Sons. Refreshments were sponsored by Enza Zaden.
- More detailed information on the varieties in the trial - including varietal resistance to disease and pests - may be obtained by contacting Bruce Napier of NIAB at firstname.lastname@example.org
Ian Gillott is a consultant and former technical director of the British Leafy Salads Association
This year I was the invited speaker at the NIAB salad trial - the breeders for which come up with something innovative every year.
I gave a personal view of how I see the UK salad industry and how it could progress in the future.
I warned growers that there is much more that could be done to support the sales of salads. For example, Information leaflets adjacent to the salad sections in supermarkets would be an excellent way of infor-ming customers of the qualities of the various types of product on offer. How many people know that batavia is the best tasting lettuce? The French certainly do.
I also implored growers not to forget basic principles such as rotation. The best mildew-resistant varieties, combined with good crop protection products, will certainly contribute to avoiding crop losses from downy mildew. However, if we continue to practice over-intensification and plant lettuce into land infected with the resting spores of the downy mildew fungus, we have only ourselves to blame for bad husbandry.
I also reflected on the development of the industry over the past 40 years when I told growers that some of the most significant developments during this period have been the introduction of the saladin types, the advent of cold chain and the move toward growers supplying directly to the multiples.
But the industry has also not been without its difficulties along the way - with major problems caused by lettuce root aphid attacks in the 1970s and early 1980s. The "golden bullet" has undoubtedly been the introduction of imidacloprid seed dressing, which solved the lettuce root aphid problem. Imidacloprid was, and still is to this day, applied as a specific off-label approval (SOLA).
Growers owe much to the Horticultural Development Company for its support to the salad industry - not just for its help in obtaining these SOLAs but through the many other salad projects it has supported and is continuing to support. Without its help the industry today would almost certainly be in a much weaker position.