This year's courgette variety demonstration was hosted on the National Institute of Agricultural Botany's (NIAB) trial farm north of Cambridge and featured 16 varieties from four seed houses.
"We pick the crop on Monday, Wednesday and Friday. While this may not fully reflect commercial practice, we need to balance the cost of coming through the crop every day with a reasonable comparison of commercial performance," explains the NIAB's Bruce Napier.
He also stressed at the event that, with another two weeks of harvesting still to complete, the yield figures were not final but indicative of the first part of the season only. "We had a dry June, but a bit of rain in July," says Napier. "The crop has received a bit of irrigation (see box) but maybe not as much as some commercial crops."
Like most commercial crops this year, the trial site was affected by disease earlier than normal. "Mildew came in earlier this year because of the wet July and it affected everything, including green material." Given these conditions, the resistant varieties in the trial displayed features more akin to tolerance than full resistance.
"Some of the plots are just starting to run out of steam and we recognise that we are not always getting the full potential," adds Napier. "We also didn't go for true baby courgette production. One reason is the restrictions we had on the timing of picking and it is also a different specification altogether. If we had gone for baby production we wouldn't have half the varieties here."
Ambassador from Seminis is an old variety but was used as control for the trial despite only producing a mean yield of 33.9 tonnes per hectare for the six-week period, the second lowest in the trial.
"Although one of the oldest varieties in the catalogue, this year it has performed quite well, especially in the early slot where its vigour is of use in establishing quick, early growth," says Colin Creese of Seminis. "It is very much the 'standard' variety in terms of fruit shape and colour." He adds that its vigour also helped it to keep growing despite suffering from early mildew.
Also from Seminis, Acceste yielded 40t/ha against a mean of 34t/ha across all varieties, despite having one of the smallest habits. "It has excellent fruit shape and colour, which is a slightly darker green," says Creese. "It is now used extensively in baby courgette production, where its ability to harvest easily with good flower abscission is key."
On trial for the first time was Panter, the first variety to be picked, which showed below average yields at 30.4t/ha. "This is the first year of trials of this variety, which is new to the UK, being both mildew and virus tolerant," explains Creese. "Yield in the trials is slightly below mean average but harvesting was approximately three days earlier than the main-season trial varieties."
The quality of newer varieties has improved considerably in recent years, says Syngenta's Nigel Kingston. For example: "There is no comparison in the size of the blossom scar in new varieties such as Syros compared with some of the older standards."
He sees Syros performing best in the second crop slot, although it can also be used for early production. Its six-week yield of 36.5t/ha was good, although early yield losses in marketable fruit this year appear atypical. "It was the top variety for marketable yield at NIAB in 2010 and has been in the top three for the past two years," he adds.
"Syngenta's breeding is focused on resistance to viruses and powdery mildew," he explains. "We have intermediate resistance and are working on getting high-level resistance. Total yield and length of cropping are also important, as is increasing marketable yield. For example, reduced blossom scarring means reduced end rots, something we account for with our in-house shelf life testing. We are the market leaders for courgettes in France and one of the top two in the UK."
This position is helped by two early varieties in the form of Mikonos and Cronos, both of which have a high yield potential, while Cronos's breeder claims the bonus of good resistance to powdery mildew. Although producing lower than average six-week yields in the trial at 30.5t/ha, Mikonos is a good choice for growers seeking a variety to perform well throughout the season, says Kingston.
Despite the fact that it has "been around for quite a while", El Greco from Nickerson is "still an important part of people's programmes due to its high yields", says the firm's Nigel Hodson. With a six-week yield of 40.5t/ha on the NIAB site, Napier agrees that it is "high-yielding in the early period" but warns that "it does tail off". Hodson adds that when grown in low-risk situations there is no appreciable virus and it has a good fruit shape.
New to Nickerson from Vilmorin's breeding programme is Tendor (CV2436), first seen in NIAB trials last year. Although its six-week yield was 31.4t/ha, it has a long fruiting period and last year it kept cropping well into the 7th and 8th week.
"The overall yield will be up," Hodson predicts. "It has quite an exceptional fruit shape and feedback from our trials this year has been very positive." With claimed intermediate resistance to CMV, ZYMV and WMV and commercial trials suggesting high marketable yields, Tendor is likely to be popular when it becomes available in 2012.
Sister company Clause is also strong on courgettes, with six varieties in the NIAB trials. "Our main courgette with tolerance to ZYMV is Tosca F1," says Paul Corfield. "It's heavily used in Kent, Cornwall and the Vale of Evesham and we are looking to promote it wider as virus becomes more of an issue, for example in the Wisbech area."
The company has a large portfolio and an active breeding programme, but not all are sold in the UK. As well as traditional green varieties, the company can supply white, yellow and Lebanese types.
New breeding is looking at further improving virus resistance and two new numbers, CLX125 and CLX468, both have good resistance potential, although six-week yields of 32.2 and 32.8t/ha respectively are average at best. Napier also reported a tendency for both to produce slightly club-like fruit at larger sizes.
With the exception of Panter, which was sown three days later, the crops were sown into 77 modules in the glasshouse on 10 May. Ambassador from Seminis was used as the control, although low yields may cause this to be reviewed in future.
The crops were planted into medium silt on 1 June at 60x60cm spacing through black polythene mulch used for weed control. A base dressing of 250kg/ha of muriate of potash was applied and the site was given 100kg/ha of nitrogen before covering. Four 20mm applications of water were applied during the earlier growing season.
The first crop of Cronos was picked on 7 July with the other varieties first picked four days later. Picking was done every Monday, Wednesday and Friday. The yields quoted in this article represent the first six weeks of data only (as of 24 August) and are not final. The average six-week yield across the whole trial was 33.87t/ha.
The difficult start to this year has made quality difficult for growers and marketing companies, but it has also resulted in steady crop availability throughout the season. Growers reported a variable start thanks to the weather, with some low yields, but in the East a real flush of crops was seen as the weather broke.
"It's been a hard growing season," says Mack Multiples buyer Peter Waldock. "Early on it was relatively wet with cold nights, but sales have been very good. We haven't seen big flushes of crop and movement has ticked along steadily. But quality has been hard work."
Yields have been steady, although mildew was a particular problem earlier in the year. "However, if the current cold nights don't go away, it will affect the end of the season."