Final Report for Trial No. 1975 – Autumn heading Cauliflower 2015

Autumn heading Cauliflower

Final Trials Report

2015

Written by Debbie Roe Trials Office, RHS Garden Wisley, Woking, Surrey, GU23 6QB

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RHS Trial of Autumn heading Cauliflower

Introduction Cauliflower is one of several vegetables of the species Brassica oleracea, in the family Brassicaceae. Brassica oleracea also includes broccoli, Brussels sprouts, cabbage and kale, though they are of different cultivar groups, cauliflowers being in the Botrytis Group. There is a main group for each season (spring, summer, autumn and winter) but many overlap. This trial focused on cultivars with white heads, suitable for harvesting in the autumn in September and by the end of October. Trial Location The trial was held at the trial ground of Elsoms Seeds Ltd, Spalding, Lincolnshire. Objectives The objectives of the trial were to assess a range of cultivars and to recommend the Royal Horticultural Society’s Award of Garden Merit (AGM) to outstanding cultivars for garden use. Judging The Cauliflower Trial Assessment Forum viewed the trial on 22 September and 14 October 2015 and assessed the plants using the following judging criteria:

uniformity

yield

quality (leaf cover, curd colour & solidity)

disease tolerance

maturity The members of the forum were: R Bailey, P Dawson, M Day, M Fletcher, I Gillott, A Hughes, T Hewitt, D Jeffery, C Randel, B Smith. Entries There were 27 entries, submitted by various seed companies in the UK. Cultivation The trial was sown on 29 April into 308 modules in Sinclair modular compost with vermiculite and was drenched with Basilex (active ingredient: tolclofos-methyl) for mildew control. It was noted that three varieties (Aviron, Di Verona Precoce and Goodman) had poorer/slower germination but still produced enough plants for the trial. The trial was planted out on 2 July in soil of silt loam, pH 7.8 – 8.0, with 60cm between plants (48 plants per entry), which the forum noted to be a generous spacing but good for the later cultivars. Elsoms protected the trial initially with an electrified rabbit netting fence and also used an auditory bird scarer. There was a good, uniform take after planting with only three entries missing a single plant.

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Seedlings in the propagation unit

Trial entries planted out in the trial ground at Elsoms

Liquid fertilisers were applied on 14 July (Double Top, an Ammonium Nitrate based fertiliser) and on 7 September (OptE Sul, a trace element mix). The following pesticides were applied:

on 2 July, a herbicide Springbok (active ingredient: dimethenamid-p + metazachlor)

on 5 August, fungicides Rudis (prothioconazole) and Folio Gold (chlorothalonil + metalaxyl-M) and insecticides Steward (indoxacarb) and Laidir 10 CS (lambda-cyhalothrin)

on 27 August, insecticide Hallmark with Zeon Technology (lambda-cyhalothrin)

on 7 September, fungicides Folio Gold (chlorothalonil + metalaxyl-M) and Plover (difenoconazole) and insecticide Alert (alpha-cypermethrin)

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Findings

Variety Days % Uniformity Quality (1 - 9) cm

50% mature

marketable small (1 – 9)

Leaf cover

curd colour

curd solidity

curd depth

curd width

White Excel 73 100 0 9 6 7 8 10 15

Goodman 73 92 8 5 4 7 8 10 14

Nessie 74 100 0 8 7 8 8 12 18

Tirza 76 100 0 9 7 8 8 10 14

All the Year Round 77 40 60 3 4 6 6 7 13

Gipsy 77 100 0 7 6 8 8 7 13

Nemo 78 100 0 9 7 8 8 9 14

Cheesy 78 97 3 7 8 8 8 9 14

Clarify 79 100 0 7 8 5 8 11 17

Liria 80 100 0 8 7 8 8 14 15

Moby Dick 81 98 2 8 7 8 8 12 18

Boris 82 98 2 7 7 8 8 15 17

White Step 83 100 0 9 8 8 8 12 16

Sapporo 83 100 0 5 6 7 8 11 14

Aviron 83 100 0 8+ 7+ 8 8 12 15

Igloo 85 75 25 7 6 6 8 8 15

Amsterdam 87 98 2 8 7 6 8 14 16

Clapton 87 100 0 9+ 8+ 8 8 11 15

Skywalker 90 100 0 8 8+ 8 8 12 18

Raleigh 91 100 0 9 8 8 8 15 17

Kestel 94 100 0 * * 8 * * *

Pavilion 95 100 0 8+ 8+ 8 8 12 16

Amandine 98 100 0 8+ 9 8 8 12 19

Regata 100 100 0 9 8+ 8 8 16 19

Telde 130+ * * 8+ 8+ 8 8 13 15

Belot 150+ not

recorded

Di Verona Precoce

not recorded

Uniformity and quality were both judged against a scale of 1 to 9, with 9 being the most uniform or best quality. The asterix * denotes that no information was recorded. Recommendation for the Award of Garden Merit (AGM) The following are the plants thought to fulfil the Award of Garden Merit criteria during the trial and to be worthy of receiving the award. The criteria which a plant needs to fulfil in order to receive the award are:

excellent for ordinary use in appropriate conditions

available

of good constitution

essentially stable in form and colour

reasonably resistant to pests and diseases

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Hardiness rating H3 Temperature range: -5 ºC ~ +1 ºC Category: Half-hardy - unheated glasshouse / mild winter Definition: Hardy in coastal and relatively mild parts of the UK except in severe winters and at risk from sudden (early) frosts. May be hardy elsewhere with wall shelter or good microclimate. Likely to be damaged or killed in cold winters, particularly with no snow cover or if pot grown. Can often survive with some artificial protection in winter.

The Cauliflower Trial Assessment Forum recommended the Society's Award of Garden Merit to the following entries, all successful cultivars are hybrids:

‘White Step’ AGM (H3) 2015 (Trial Entry 8) Sent by Thompson & Morgan Forum comments: Excellent colour. Small plant and small frame. Very well covered curds. Uniform crop. Curd width 16cm & depth 12cm Available from: S E Marshall, Thompson & Morgan

‘Raleigh’ AGM (H3) 2015 (Trial Entry 10) Sent by D T Brown Forum comments: Very uniform. Good density and colour of curd. Leaves are a good dark green. Supposed to have an anti-pinking gene. Curd width 17cm & depth 15cm Available from: D T Brown, Medwyns of Anglesey, Shelley Seeds, Unwins

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‘Boris’ AGM (H3) 2015 (Trial Entry 11) Sent by Hazera Seeds Forum comments: Good, deep, round curd. Generally largest cultivar in trial. Curd width 17cm & depth 15cm Available from: Dobies of Devon, Medwyns of Anglesey, Moles Seeds, Shelley Seeds, Thompson & Morgan, W Robinson & Son

‘Clapton’ AGM (H3) 2015 (Trial Entry 16) Sent by S E Marshall Forum comments: Excellent cauliflower. Neat, well covered variety. Lovely curds. Good, upright habit, not spreading too much. Would need well-fertilised soil. Some club-root resistance but would still need to rotate crops. Curd width 15cm & depth 11cm Available from: Dobies of Devon, D T Brown, Kings Seeds, Medwyns of Anglesey, Moles Seeds, Mr Fothergill’s, S E Marshall, Shelley Seeds, Simpson’s Seeds, Sutton Seeds, Thompson & Morgan, Unwins, Wallis Seeds

The Cauliflower Trial Assessment Forum recommended the Society's Award of Garden Merit to the following entries, which already hold the AGM for summer heading: ‘Amsterdam’ AGM (H3) 2015 (Trial Entry 7) [Existing AGM (H3) 1997 – summer heading] Sent by and available from Mr Fothergill’s Forum comments: Good depth and solidity. One of the deepest relative to its width. Not ready altogether so good for home gardeners.

Curd width 16cm & depth 14cm

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‘Nessie’ AGM (H3) 2015 (Trial Entry 14) [Existing AGM (H3) 2006 – summer heading] Sent by Thompson & Morgan Forum comments: Lovely curds. Some nice big heads. Curd shape slightly uneven. Curd width 18cm & depth 12cm Available from: Dobies of Devon, Thompson & Morgan, Wallis Seeds

‘Aviron’ AGM (H3) 2015 (Trial Entry 21) [Existing AGM (H3) 2006 – summer heading] Sent by Kings Seeds. Forum comments: One of the most uniform. Nice colour. Well covered. One of the best. Plants not too big. Curd width 15cm & depth 12cm Available from: Kings Seeds, Moles Seeds, S E Marshall

The Cauliflower Trial Assessment Forum re-confirmed the Society's Award of Garden Merit to: ‘White Excel’ AGM (H3) 2002 (Trial Entry 5) Sent by Kings Seeds Forum comments: Was ready a fortnight before first assessment. Generally one of the earliest autumn-headed cultivars. Deep, solid curds. Curd width 15cm & depth 10cm Available from: Kings Seeds, Shelley Seeds

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‘Skywalker’ AGM (H3) 2002 (Trial Entry 19) Sent by Elsoms Seeds Forum comments: Exceptional leaf cover. Good curd colour and solidity. Curd width 18cm & depth 12cm Available from: Moles Seeds, Nicky’s Nursery

‘Pavilion’ AGM (H3) 2002 (Trial Entry 20) Sent by & available from Thompson & Morgan Forum comments: Good colour. Wide heads. Large frame so would need a lot of space to grow it. Curd width 16cm & depth 12cm

‘Moby Dick’ AGM (H3) 2002 (Trial Entry 22) Sent by Mr Fothergill’s Forum comments: White curds. Big cauliflower. Good width. Curd width 18cm & depth 12cm Available from: Mr Fothergill’s, Edwin Tucker

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‘Regata’ AGM (H3) 2002 (Trial Entry 25) Sent by & available from D T Brown Forum comments: Big, deep cauliflower. Well covered. Dense curd but quite lumpy. Curd width 19cm & depth 16cm The Cauliflower Trial Assessment Forum recommended the Society's Award of Garden Merit, subject to AVAILABILITY, to the following entries: It is the sender’s responsibility to notify the Trials Office that seed has become available for home gardeners to buy. ‘Tirza’ (Trial Entry 4) Sent by Hazera Seeds Forum comments: Looked particularly impressive. Cropped in 2 cuts. Well covered so will stand. Good curd colour. Curd width 14cm & depth 10cm Not currently available but should be included in S E Marshall’s 2017 catalogue

‘Liria’ (Trial Entry 9) Sent by Elsoms Seeds Forum comments: Very uniform: nice and even. Good size and shape. Creamy-white rather than white-white. Long leaf. Curd width 15cm & depth 14cm Not currently available.

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Index of Plants in the Trial Names that are struck through have been updated / corrected by RHS Botanists during the course of the trial.

Trial Entry

Name AGM

Sender

1 Nemo D T Brown

2 Clarify Unwins

3 Igloo Unwins

4 Tirza Hazera

5 White Excel 2002 (Autumn) Kings

6 All The Year Round Thompson & Morgan

7 Amsterdam 1997 (Summer) Mr Fothergill’s

8 White Step Thompson & Morgan

9 Liria Elsoms

10 Raleigh D T Brown

11 Boris Hazera

12 Gipsy 1997 (Summer) Thompson & Morgan

13 Goodman Thompson & Morgan

14 Nessie 2006 (Summer) Thompson & Morgan

15 Telde Elsoms

16 Clapton S E Marshall

17 Cheesy Johnsons

18 Sapporo D T Brown

19 Skywalker 2002 (Autumn) Elsoms

20 Pavilion 2002 (Autumn) Thompson & Morgan

21 Aviron 2006 (Summer) Kings

22 Moby Dick 2002 (Autumn) Mr Fothergill’s

23 Amandine Sakata UK

24 Belot 1993 (Autumn) Elsoms

25 Regata 2002 (Autumn) D T Brown

26 Cavolfiore Di Verona Precoce Seeds of Italy

27 Kestel Tozer Seeds

Sender details:

D T Brown, Bury Road, Newmarket, Suffolk CB8 7PQ, Tel. 0333 003 0869, www.dtbrownseeds.co.uk

Elsoms Seeds, Pinchbeck Road, Spalding, Lincolnshire PE11 1QG, Tel. 01775 715000, www.elsoms.com

Hazera Seeds UK, Joseph Nickerson Research Centre, Rothwell, Market Rasen, Lincolnshire LN7 6DT, Tel. 01472 371531, www.hazera.uk.com

Johnsons, Kentford, Suffolk CB8 7QB, Tel. 0333 321 3103, www.johnsons-seeds.com

Kings Seeds, Monks Farm, Coggeshall Road, Kelvedon, Colchester, Essex CO5 9PG, Tel. 01376 570000, www.kingsseeds.com

Mr Fothergill’s Seeds, Gazeley Road, Kentford, Suffolk CB8 7QB, Tel. 0333 777 3936, www.mr-fothergills.co.uk

Sakata UK, Spalding Road, Sutterton, Boston, Lincolnshire PE20 2EW, Tel. 01205 462810, www.sakata-vegetables.eu/vegetables/en

Seeds of Italy, Phoenix Business Centre, Unit D2, Rosslyn Crescent, Harrow, Middlesex HA1 2SP, Tel. 020 8427 5020, www.seedsofitaly.com

S E Marshalls, Alconbury Hill, Huntingdon, Cambridgeshire PE28 4HY, Tel. 0844 557 6700, www.marshalls-seeds.co.uk

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Thompson & Morgan, Poplar Lane, Ipswich, Suffolk IP8 3BU, Tel. 0844 248 5383, www.thompson-morgan.com

Tozer Seeds, Pyports, Downside Bridge Road, Cobham, Surrey KT11 3EH, Tel. 01932 862059, www.tozerseeds.com

Unwins, Alconbury Hill, Huntingdon, Cambridgeshire PE28 4HY, Tel. 0844 573 8400, www.unwins.co.uk

Please note: Sources of seed for these cultivars may vary from year to year. Acknowledgements The RHS would like to thank Elsoms Seeds Ltd for kindly hosting the trial, with especial thanks to Paul Hurst, Trials Manager, and his team for producing such an excellent trial. Photographs in the Cultivation section were taken by T Hewitt and all others by M Day.

Source: Horticultural Trials and Relations, RHS Garden Wisley, Woking, Surrey GU23 6QB

Tel: 01483 224234 & Email: trials@rhs.org.uk

More information about RHS Trials and other Trials reports can be found on the RHS Website at www.rhs.org.uk/trials