Best practice guidelines for seed potato

production Denis Griffin, Fiona Hutton, Brian

Rigney, Steven Kildea and Michael Hennessy

Why use clean seed? • Seed quality is one of the most important yield

determining factors that can be controlled

• Potatoes clonally propagated in soil

• Tubers spread soil borne diseases

• Tubers accumulate seed borne diseases

• Certification scheme established to ensure varietal purity, generation control and freedom from disease.

Seed or Ware

• Ware production should maximise yield at an acceptable quality for a particular market outlet

• Seed production should maximise quality at an acceptable yield for profit

• Seed is a premium product

Specialist Seed Producer • Quality land selection • Early planting and early harvesting • Pay attention to geography and variety • Disease prevention or minimization • Field roguing to certification standards • Good agronomy, size management • Good stock control and storage

Geographic location advantages and disadvantages

● Northern regions have an advantage for production of virus free seed due to lower temperatures ● Elevation also limits virus spread by aphids ● The south and east of the country with less rainfall will have less disease pressure from both blight and blackleg ● Southern regions may also have an advantage for early harvest and export.

Land selection ● High grade seed area

● Seed potato land scarce

● Large bank of virgin land

● Access to irrigation

● Proximity to ware crops

● Fields with a history

● Must be free from PCN

Land selection ● Know your fields

● Soil test ● pH,

● Soil N Index

● P and K

● Soil structure

● Rotation relative to potatoes

● Seed crops deserve the best land!

Globodera pallida Mixed Species Globodera rostochiensis

Land selection - PCN

• 10-15% of Irish land sampled is infested

• Need to minimise spread

• Longer rotations

• Introduce new land to rotation

• Use certified seed

• Promote use of resistant varieties

Data courtesy of DAFM

Soil and Seed Borne Diseases

Powdery scab Black Scurf

• Varying control methods depending on disease • Chemical control expensive, not always effective • Rotation, clean seed and fresh land • Varietal resistance

Roguing

• Diseases that are visible in the foliage, seed borne

• Off types, other varieties • Must begin early in the

season • Keep inoculum levels low • Easier to remove

immature plants • Rogue as often as

necessary but at least twice prior to inspections

Rhizoctonia

Blackleg

• One of the most problematic diseases in seed production

• Varieties differ greatly in susceptibility

• Pectobacterium spp most important in Ireland

• Dickeyea not established in Ireland

• Rouging necessary to meet certification standards, only effective if plant numbers are low and carried out early in season

• Harvesting conditions, crop drying and storage are important for control

Gillian Young AFBI

Potato viruses Aphid transmitted

Persistent PLRV Non persistent PVY PVA Contact PVX PVS

LR1%

S1%

A13%

Y16%

YN36%

X33%

LRSAYYNX

DAFM - Total virus frequency 2006-2012

Virus Y • Virus Yo and Yn were predominant • Potato tuber necrotic ringspot disease

caused by YNTN recently discovered

• Economically most important virus of seed potatoes and hardest to control

• Non persistent virus acquired and transmitted in less than 30 seconds

• Non colonising aphids role • Insecticides prevent population build

up but not infection • PVY levels dependent on previous

years infection • Mineral oils sprayed at weekly

intervals may be of use in future • Roguing effective control measure if

symptoms visible

Virus Y secondary symptoms

Yo secondary symptoms Yn secondary symptoms

Potato Virus X

• Second most important Virus

• Contact transmission

• Varietal resistance

• Easy to identify • Roguing effective

Size management for seed

• Target yields 30-35t/ha

• Maximise valuable 35-55mm grade

• Plant high seed density 4-5 t ha-1 15-20cm spacing

• Break apical dominance, do not sprout seed

• Can reduce nitrogen rate by 40-60 kg/ha

• Variety dependant

• Early burn down and harvest spreads work load

0

1

2

3

4

5

6

7

29-May 18-Jun 08-Jul 28-Jul 17-Aug 06-Sep 26-Sep 16-Oct

LAI

Potato canopy management

Crop planted April 23rd

0

1

2

3

4

5

6

7

29-May 18-Jun 08-Jul 28-Jul 17-Aug 06-Sep 26-Sep 16-Oct

LAI

Tuber Bulking

Potato canopy management

Crop planted April 23rd

0

1

2

3

4

5

6

7

29-May 18-Jun 08-Jul 28-Jul 17-Aug 06-Sep 26-Sep 16-Oct

LAI

Tuber Bulking

Potato canopy management

Crop planted April 23rd

0

1

2

3

4

5

6

7

29-May 18-Jun 08-Jul 28-Jul 17-Aug 06-Sep 26-Sep 16-Oct

LAI

Tuber Bulking

Potato canopy management 30 days less exposure to Fungal Bacterial and Viral infection

Crop planted April 23rd

Haulm Killing and Harvesting

• Use to regulate seed size • Flailing or haulm cutting rare in Ireland • Kill the haulm as quickly as possible • Monitor and eliminate regrowth • Maintain aphid and blight programmes • Factor maturity into achieving skin set • Ensure good skin set before harvesting • Harvest seed as dry as possible

Storage • Store and grader hygiene

• Correct labelling

• Segregation of stocks

• Drying and prevention of condensation

• Handling at the correct temperature

• Prevention of dust borne diseases

• Protection from frost • Storage temperature dependant on variety

dormancy

Take Home Messages • Dedicated seed crop • Early planting in your best land • Roguing • Size management • Early burnoff, early harvest • Dry in store • Hygiene throughout the cycle

Acknowledgements

• DAFM • Gerry Doherty • Denis Bonner • Barry O Reilly • John Eivers • Gabriel Roe

• IPM • Colm McDonnell

• Teagasc • Dan Milbourne • John Spink • John Burke

Thank you