Why use clean seed?
• Seed quality is one of the most important yielddetermining 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 varietalpurity, generation control and freedom from
disease.
Geographic location advantages and disadvantages
● Northern regions have an
advantage for production ofvirus free seed due to lower
temperatures
● Elevation also limits virusspread by aphids
● The south east of the country
with less rainfall will have lessdisease pressure from both
blight and blackleg
● Southern regions may alsohave an advantage for early
harvest and export.
Land selection
● High grade seed area
● Seed potato land scarce
● Large bank of virgin land
● Consider rotation
● Access to irrigation
● Proximity to ware crops
● Fields with a history
● Must be free from PCN
Size management for seed
• Target yields 30-35 t ha-1
• Maximise valuable 35-55mm grade
• Plant high seed density 4.2-5 t ha-1
• Break apical dominance, do not sprout seed
• Can reduce nitrogen rate by 40-60 kg ha-1
• Variety dependant
• Early burn down and harvest spreads work load
Size management
0
1
2
3
4
5
6
7
40 60 80 100 120 140 160 180
Days After Planting
LA
I
80 tuber bulking days
Adapted John Burke
Size management
0
1
2
3
4
5
6
7
40 60 80 100 120 140 160 180
Days After Planting
LA
I
80 tuber bulking days
Adapted John Burke
Blackleg
• One of the most problematic diseasesin seed production
• Varieties differ greatly in susceptibility
• Pectobacterium spp most important inIreland
• Dickeyea not established in Ireland
• Important to avoid introduction ofDickeyea
• Rouging necessary to meetcertification standards
• Harvesting conditions, crop dryingand storage are important for control
Gillian Young AFBI
Virus disease prevalence
34
27.4
41
1311
X
Yo,Yc
Yn
A
S
LR
6
83
35 3
X
Y
Y
A
S
LR
Fiona Hutton and Gerry Doherty
DAFF - 5,635 Samples tested over a 3 yearperiod 2008, 2009, 2010
Teagasc - 2,538 Samples tested over a 3 yearperiod 2008, 2009, 2010
Virus Y
• Two strains known in Ireland
• Virus Yo and Yn
• No Yntn
• Economically most important virus ofseed potatoes and hardest to control
• Persistent virus acquired andtransmitted in less than 30 seconds
• Insecticides prevent population buildup but not infection
• Paraffinic oils sprayed at weeklyintervals may be of use in future
• Roguing only effective controlmeasure
Storage
• Store hygiene
• Correct labelling
• Segregation of stocks
• Drying and prevention of condensation
• Handling at the correct temperature
• Prevention of dust borne diseases
• Protection from frost