Final Report for Trial No. 2023 – Sweetcorn 2016 1

Sweetcorn Trial Report

2016

Written by Eva Erhart Trials Office, RHS Garden Wisley, Woking, Surrey, GU23 6QB

Final Report for Trial No. 2023 – Sweetcorn 2016 2

RHS Trial of Sweetcorn

Introduction: Sweetcorn (Zea mays) is a member of the grass family, Poaceae. Sweetcorn is a naturally occurring type of corn which produces more sugar and less starch than field corn. Traditional sweetcorn starts to lose its flavour quickly after harvesting. Plant breeders introduce new varieties each year with increased sweetness, so the objective of this trial is to assess and compare the traditional and new cultivars of sweetcorn. Trial Location The trial was held on the Trials Field at RHS Garden Wisley and a duplicate trial was hosted at RHS Garden Rosemoor. 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 Sweetcorn Trial Assessment Forum viewed the trial on 15th and 25th August 2016 and assessed the plants using the following judging criteria: ▪ Taste – (raw) ▪ Colour ▪ Seed size

▪ Cob fill ▪ Date of maturity ▪ Height and standing ability

▪ Appearance; straightness of the rows on cob

▪ Cob size and cob number/plant

The members of the forum were: P Dawson, M Day, J England, I Gillott, A Hughes, S Mercer, B Newman, C Randel, S Wain, R White. Entries There were 32 entries in the trial at Wisley and 28 at Rosemoor, which were submitted by various seed companies in the UK. Cultivation at Wisley: The trial was sown on 27 April into 8 cm biodegradable pots in Melcourt compost, 2 seeds to each pot. The germinating sweetcorn plants were kept in the glasshouse for 4 weeks on 15-18 °C and were thinned (if both seeds germinated).

Prior to planting the ground was prepared:

On 17 May the drip line irrigation was installed and the landscape fabric was placed.

On 23 May the bed was fertilised with: o Sulphate of Ammonia – 50 g/m2 o Sulphate of Potash – 20 g/m2

On 24-25 May the trial was planted in Bed 5 on the trials field. Each entry was planted in a block and a guard row (from the same cultivar) was planted around the block to minimalize cross pollination.

Final Report for Trial No. 2023 – Sweetcorn 2016 3

Seedlings in the glasshouse on 18 May Planting on 25 May

The trial was irrigated after planting (on 24-25 May, 27 May) to help establishing the seedlings and in dry periods on 5 June, 10 June and 20 July. On the 21 July an electric fence was installed around the bed as the cobs were beginning to form. Even so, badgers managed to get into the bed on 5 August and eaten or destroyed the majority of cobs from entries 25 and 26. The mature cobs were harvested on 15 August, 23 August and 1 September.

RHS advice on growing your own sweetcorn can be found here: https://www.rhs.org.uk/advice/grow-your-own/vegetables/sweetcorn Recommendation for the Award of Garden Merit (AGM) The plants which fulfilled the AGM criteria during the trial and were considered 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

The plants which already had an AGM had to be re-confirmed to keep it; and if they didn’t fulfil the above mentioned criteria and are out-classed by newer varieties, their AGM was rescinded.

Hardiness rating H2 Temperature range: 1 ºC – 5 ºC Category: Tender – Cool or frost-free glasshouse Definition: Tolerant of low temperatures, but will not survive being frozen. Except in frost-free inner-city areas or coastal extremities, requires glasshouse conditions in winter, but can be grown outdoors once risk of frost is over.

Brix reading Brix scale helps to determine the soluble solids (sugars, minerals) of the cob and to identify its potential sweetness (an aspect of quality). A higher brix means better flavour and better nutrient value. Brix of sweetcorn usually vary between 6 and 24, where:

Poor Average Good Excellent

Brix of sweetcorn 6 10 18 24

Final Report for Trial No. 2023 – Sweetcorn 2016 4

THE SWEETCORN TRIAL ASSESSMENT FORUM RECOMMENDED THE SOCIETY’S AWARD OF GARDEN MERIT TO THE FOLLOWING ENTRIES:

'Goldcrest' AGM (H2) 2016 (Trial Entry 6)

Sent by Kings Seeds.

Wisley Rosemoor

Average weight/cob

373 g 320 g

Average no. of rows on cob

17 -

Average length of cob

19.6 cm 20 cm

No. cobs/plant 2 1

Average height of plant

225 cm -

Brix 17 -

Forum comments: Supersweet. Well filled and uniform. Even sized cobs. Quite tall plant.

Available from: Kings Seeds, Seed Parade, Simpsons Seeds, Tuckers, Unwins.

'Mirai Gold' AGM (H2) 2016 (Trial Entry 12 & 21)

Sent by Pro-Veg Seeds (TN12) and Mr Fothergill’s Seeds (TN21).

Entry Wisley Rosemoor

Average weight/ cob

TN12 368 g 300 g

TN21 385 g 340 g

Average no. of rows on cob

TN12 &

TN21 16 -

Average length of cob

TN12 17.6 cm 18.3 cm

TN21 19.1 cm 17.3 cm

No. cobs/ plant

TN12 1-2 1

TN21 2 1

Average height of plant

TN12 170 cm -

TN21 186 cm -

Brix TN12 16 -

TN21 15 -

Forum comments: Augmented supersweet. Long cobs. Taste is good, tender to eat. Grains are quite big. Fairly short plants.

Available from: D T Brown, Mr Fothergill’s Seeds, Pro-Veg Seeds, Unwins.

Final Report for Trial No. 2023 – Sweetcorn 2016 5

THE SWEETCORN TRIAL ASSESSMENT FORUM RE-CONFIRMED THE SOCIETY’S AWARD OF GARDEN MERIT TO:

'Sparrow' AGM (H2) 2009 (Trial Entry 10)

Sent by Mr Fothergill’s Seeds.

Wisley Rosemoor

Average weight/cob

288 g 300 g

Average no. of rows on cob

17 -

Average length of cob

18 cm 18 cm

No. cobs/plant 2 1

Average height of plant

187 cm -

Brix 16 -

Forum comments: Xtra tender. Early. Very good shaped cob. 16, straight rows. Pericarp is thin, very tender. Grains are quite big. Very sweet. Good taste.

Available from: Mr Fothergill’s Seeds.

'Swift' AGM (H2) 2003 (Trial Entry 11)

Sent by Kings Seeds.

Wisley Rosemoor

Average weight/cob

393 g 290 g

Average no. of rows on cob

16 -

Average length of cob

20.5 cm 20 cm

No. cobs/plant 1-2 2

Average height of plant

201 cm -

Brix 17 -

Forum comments: Xtra tender. Very popular variety. Performs well. Very thin pericarp – prone to damage. Very sweet.

Available from: Chiltern Seeds, D T Brown, Kings Seeds, Mr Fothergill’s Seeds, Simpsons Seeds, Suttons Seeds, Thompson & Morgan.

Final Report for Trial No. 2023 – Sweetcorn 2016 6

MIRAI WHITE M421 'Mirai 421W' AGM (H2) 2009 (Trial Entry 17)

Sent by Pro-Veg Seeds.

Wisley Rosemoor

Average weight/cob

371 g 280 g

Average no. of rows on cob

15 -

Average length of cob

18.9 cm 18 cm

No. cobs/plant 2-4 1

Average height of plant

214 cm -

Brix 15 -

Forum comments: Augmented supersweet. Lot of foliage, colour is great. Lot of cobs. Has reputation for whiteness.

Available from: Pro-Veg Seeds, Suttons Seeds, Thompson & Morgan.

MIRAI PICNIC 'Mirai 003Y' AGM (H2) 2009 (Trial Entry 20)

Sent by Pro-Veg Seeds.

Wisley Rosemoor

Average weight/cob

309 g 220 g

Average no. of rows on cob

16 -

Average length of cob

15.1 cm 13.3 cm

No. cobs/plant 2 1

Average height of plant

230 cm -

Brix 17 -

Forum comments: Yellow augmented supersweet. Most widely listed Mirai cultivar. Small cobs. Tall plants. Good cob fill.

Available from: Dobies of Devon, D T Brown, Marshalls Seeds, Pro-Veg Seeds, Suttons Seeds.

Final Report for Trial No. 2023 – Sweetcorn 2016 7

'Lark' AGM (H2) 2003 (Trial Entry 22)

Sent by Thompson & Morgan.

Wisley Rosemoor

Average weight/cob

355 g 290 g

Average no. of rows on cob

16 -

Average length of cob

18.2 cm 16 cm

No. cobs/plant 2 1

Average height of plant

211 cm -

Brix 18 -

Forum comments: Xtra tender. 16 rows. Quite tall. Widely grown by gardeners. Good variety.

Available from: A L Tozer, Chiltern Seeds, D T Brown, Kings Seeds, Marshalls Seeds, Simpsons Seeds, Thompson & Morgan, Unwins.

'Marshall Honeydew' AGM (H2) 2009 (Trial Entry 23)

Sent by Marshalls Seeds.

Wisley Rosemoor

Average weight/cob

356 g 290 g

Average no. of rows on cob

16 -

Average length of cob

17.7 cm 16.3 cm

No. cobs/plant 2 1

Average height of plant

197 cm -

Brix 15 -

Forum comments: Xtra tender. Nice leaves. Large seeds. Well filled.

Available from: Marshalls Seeds.

Final Report for Trial No. 2023 – Sweetcorn 2016 8

'Earlibird' AGM (H2) 2003 (Trial Entry 25)

Sent by A L Tozer.

Wisley Rosemoor

Average weight/cob

310 g 340 g

Average no. of rows on cob

14 -

Average length of cob

19 cm 19.3 cm

No. cobs/plant 1 1

Average height of plant

186 cm -

Brix 9 -

At Wisley measurements were taken from only 1 cob and a few damaged plants, as the majority has been destroyed by badgers.

Forum comments: Supersweet. Early. Quite sweet. Badgers have got into the bed and eaten most of the cobs. The forum members had to rely on their experience with this cultivar and agreed that it should keep its AGM.

Available from: A L Tozer, Chiltern Seeds, Dobies of Devon, Kings Seeds, MoreVeg, Simpsons Seeds, Suttons Seeds.

'Ovation' AGM (H2) 1996 (Trial Entry 28)

Sent by A L Tozer.

Wisley Rosemoor

Average weight/cob

384 g 340 g

Average no. of rows on cob

13 -

Average length of cob

20 cm 18.7 cm

No. cobs/plant 1 1

Average height of plant

223 cm -

Brix 15 -

Forum comments: Supersweet. Quite an old variety. 12 rows. Nice straight rows. Quite thick skin. Quite big cobs.

Available from: A L Tozer, Thompson & Morgan, MoreVeg.

Final Report for Trial No. 2023 – Sweetcorn 2016 9

THE SWEETCORN 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.

'Mirai Music' AGM (H2) 2016 (Trial Entry 19)

Sent by Pro-Veg Seeds.

Wisley Rosemoor

Average weight/cob 370 g -

Average no. of rows on cob

17 -

Average length of cob

16.8 cm

-

No. cobs/plant 2 -

Average height of plant

216 cm

-

Brix 16 -

Forum comments: Augmented supersweet. Bicolour. Attractive. Shorter cobs and very well filled. Very even. Nice sample. Very sweet.

Not yet available.

THE SWEETCORN TRIALS ASSESSMENT FORUM RECOMMENDED TO RESCIND THE SOCIETY’S AWARD OF GARDEN MERIT FROM: 'Northern Xtra Sweet' AGM (H2) 1996 (Trial Entry 26) Sent by Thompson & Morgan. Forum comments: Supersweet. Very old variety. Still popular. Cold tolerant. Reliable for early production. Widely used commercially in other countries. A lot grown in Germany. Cob sticks out from wrapping leaves. Tough pericarp. Out-classed.

'Seville' AGM (H2) 2009 (Trial Entry 29) Sent by A L Tozer. Forum comments: Supersweet. Quite a tall plant. Mid-late variety. Sweet. Nice cobs. Out-classed.

'Sundance' AGM (H2) 1993 (Trial Entry 32) Sent by Sutton Seeds. Forum comments: Old, normal sugary variety. 14 rows. Rows are not straight. Bit starchy taste. Skin is tougher than newer varieties. Short plant. Out-classed.

Final Report for Trial No. 2023 – Sweetcorn 2016 10

Index of Plants in the Trial

Trial Number

Cultivar Name AGM Sender

1 Earliking Kings Seeds

2 Alojzia Pro-Veg Seeds

3 Primetime Pro-Veg Seeds

4 ACX SS7078Y D T Brown

5 Rising Sun Pro-Veg Seeds

6 Goldcrest Kings Seeds

7 Sweetstar Pro-Veg Seeds

8 ACX SS7403 RY D T Brown

9 Arnia Pro-Veg Seeds

10 Sparrow AGM 2009 H2 Mr Fothergill’s

11 Swift AGM 2003 H2 Kings Seeds

12 Mirai Gold Pro-Veg Seeds

13 Mirai Mentor Pro-Veg Seeds

14 Mirai Maker Pro-Veg Seeds

15 Mirai 308BC Pro-Veg Seeds

16 Snogum Pro-Veg Seeds

17 MIRAI WHITE M421 'Mirai 421W'

AGM 2009 H2 Pro-Veg Seeds

18 Mirai Meridian Pro-Veg Seeds

19 Mirai Music Pro-Veg Seeds

20 Mirai Picnic (M 003Y) AGM 2009 H2 Pro-Veg Seeds

21 Mirai Gold Mr Fothergill’s

22 Lark AGM 2003 H2 Thompson & Morgan

23 Marshall Honeydew AGM 2009 H2 Marshalls Seeds

24 Aranka Pro-Veg Seeds

25 Earlibird AGM 2003 H2 A L Tozer

26 Northern Xtra Sweet AGM 1996 H2 Thompson & Morgan

27 Meteor Pro-Veg Seeds

28 Ovation AGM 1996 H2 A L Tozer

29 Seville AGM 2009 H2 A L Tozer

30 ZHY4739 OR Pro-Veg Seeds

31 Escalate Pro-Veg Seeds

32 Sundance AGM 1993 H2 Suttons Seeds

Final Report for Trial No. 2023 – Sweetcorn 2016 11

Sender details:

A L Tozer, Pyports, Downside Bridge Rd, Cobham KT11 3EH, Tel. 01932 862059, www.tozerseeds.com

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

Kings Seeds (EW King), Monks Farm, Colchester CO5 9PG, Tel. 01376 570000, www.kingsseeds.com

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

Marshalls Seeds, Alconbury Hill, Huntingdon, Cambs PE28 4HY, Tel: 0844 573 6700, www.marshalls-seeds.co.uk

Pro-Veg Seeds, 6 Shingay Lane, Sawston, Cambridge CB22 3SS, Tel. 01223 499131, www.provegseeds.com/

Sutton Seeds, Woodview Road, Paignton, Devon TQ4 7NG, Tel: 01803 696300, www.suttons-seeds.co.uk

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

Please note: Sources of seed for these cultivars may vary from year to year. Acknowledgements Cover photograph was taken by Liz Cowan. Pictures in cultivation section were taken by Eva Erhart. Pictures of the awarded sweetcorns were taken by Katy Simms.

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