1. WORK OF MULTIPLE ORGANIZATIONS TO IMPROVE SEED
POTATO HEALTH IN U.S.A.
And an example of change to reduce Potato virus Y in seed lots.
Jonathan Whitworth, USDA‐Agricultural Research Service
Phil Nolte, University of Idaho
9th Triennial African Potato Association Conference, Naivasha, Kenya
June 30 – July 3, 2013

2. Background
• Managed seed potato certification programs in Colorado
and Idaho (10 yrs)
• USDA‐ARS Research Plant Pathologist (10 yrs)
– Research focus, Potato virus Y
– Located in Southeast Idaho, USA
Jonathan Whitworth

3. • Idaho grows 30% of USA potatoes (2012 crop)
– Idaho total = 56242 ha (138,976 a)
– USA total = 184,874 ha (457,610 a)

5. Seed AreasCommercial
Areas

6. USA Fall Potato Production Areas
50 %
28%
5%
NPC, Statistical Yearbook 2009
5% all
other
areas

7. Foundation of Certification
• Grower enters eligible seed into
program
• Field Inspections
• Storage/Harvest Inspection
• Post‐harvest inspection
• Shipping point inspection

8. Tissue culture Greenhouse minitubers
Field production of seed

9. Inspections

10. Vine desiccation by sulfuric acid (H2SO4) or herbicide (Reglone®, diquat)
Harvest

11. California Post‐Harvest Test

12. Shipping Point Inspection

14. Plant Health
Certificate
NORTH AMERICAN CERTIFIED SEED POTATO HEALTH CERTIFICATE - CROP YEAR 2002
Grower Importer
Name Idaho Sunny Seed Inc.
City, State/Prov. Seed Town, Idaho
Variety Russet Norkotah Quantity Shipped
Size
Lot Certification
Certification # 52323551 Lot origination from tissue culture No Yes X
Seed Class/Gen G3 Year micropropagated for planting 1998
Certifying State Idaho by
Production environment pedigree: Fill 1 column per production year; use different intitials in Greenhouse or Field boxes for different farms
(e.g. JSF for John Smith Farms); indicate a tuber-united lot with a '+' after the farm initials; describe other footnotes in 'Notes' below.
1998 1999 2000 2001 2002 Year of production
Greenhouse (insect excluding) & sterile soil
Field (note special measures[e.g. row covers] belo
59448990 50441890 51442390 52323551 Certification Number Number of years produced in
ID ID ID ID Certifying State field soil: 4
Summer Field Readings Field Inspection Post Harvest Readings
1st 2nd 3rd Final Visual Location California
0 0 0 % Leafroll 0
0.04 0 0 % Mosaic Sample No 400
0 0 0 % Varietal 0 Plant Count 380
Mixture
ELISA test results for latent viruses
Less than 0 % Wilts % PVY 1
Less than 0 % Witches Broom % PVX
Other diseases Not known to No. of years since last found on this This year
occur in grower's farm, or NONE ON RECORD apparently free Status
grower's area if free > 5 years by inspection Unknown
Bacterial Ring Rot
Late blight
N o tes
T he abo ve info rmatio n is accurate to the best o f o ur kno wledge.
Jonathan Whitworth / Area Manager
Program Official / Title
Agency
Approved for use by the Cert if ication Section of the Potato Association of America - December 2001
Superior Greenhouses, Inc.
NOR
X
(208) 529-4358
Idaho Crop Improvement Association Fax
11/12/02
Date
(208) 522-9198
Telephone
Lot info
Inspection results
Non‐quarantine
pests
Pedigree

15. Regulatory
• USDA‐APHIS, Federal “umbrella organization”
– Authority to regulate trade
• Between states in the USA
• Between countries
– Memorandum of understanding with states
• State seed certification authority
– Each state has own seed regulations but they must meet a
minimum standard
– Seed certification principles result in similar seed regulations
– Must produce quality manual listing procedures, audited by
APHIS

16. • USDA‐APHIS
– Animal Plant Health
Inspection Service
• USDA‐APHIS‐PPQ
– Plant Protection and
Quarantine
Federal Plant Protection Organization

17. Seed certification programs
• Exist in 13 states in USA
• Operate under authority of
– State Government
• State Dept. of Agriculture
– Organizations that may operate as “agents of the state”
» University (land‐grant or agricultural college)
» Grower associations

18. State seed potato regulations
• Developed by Certification Agency
• Approved by state authority (state government)
• Proposed changes to regulations in Idaho
1. Proposed by growers or scientists
2. Approved by grower advisory board
3. Approved by scientists (for validity)
4. Approved by state government

19. Political – Grower organization
• National Potato Council
– Lobby: influence legislation
• U.S. Potato Board
– Trade: promotion to USA and other countries

20. PVYNTN/N-Wi can
cause tobacco
necrosis
PVYO strain causes
vein burning and leaf
drop
PVYNTN&PVYN-Wi
strains can cause
internal and external
necrosis
Known as:
Potato Tuber Necrotic Ringspot Disease (PTNRD)

21. Yellow spotting Stem necrosis Veinal necrosis Internal necrosis
Leaf drop Ring spots External necrosis

24. PVY progression in North America
Prior 1990’s no N strains
1990’s PVYN reported N.
America
2000 PVYN reported
Pacific Northwest
2000‐2001 PVYN/NTN in
US & Canada seed
sources
2004‐2006 USA/Canada
survey
O (66%)
N (34%)
2009 USA monitoring
survey
O (44%)
N (56%)
2011 USA monitoring
survey
O (22%)
N (78%)
2012 USA monitoring
survey
O (30%)
N (70%)
FUTURE ??
Predict problems with
PTNRD

25. Problem
• PVY N strains were a quarantine pathogen
• Canada destroyed many acres in early 1990’s
in order to eradicate
• No surveys were considered because of
regulatory action
• Difficult to research due to quarantine

26. Bi‐lateral trade talks
USA: USDA‐APHIS
• Involved
– Seed Certification officials
– National Potato Council
• Grower organization
– USA Potato Board
• Grower organization
– Scientists
Canada: CFIA (Canada Food
Inspection Agency)
• Involved
– Held talks with “stake
holders”
• Grower groups
• Trade groups
– Scientists
Developed Potato Virus Management Plan
Official title: Canada/US-Management Plan for Potato Viruses that Cause
Tuber Necrosis

27. Virus Management Plan
• Included an annex that listed research needs
– Survey: 3 years all late generation seed lots
– PVY: determine symptoms in N. American cultivars
– Provide training needs
• Inspection manuals with photos of symptoms
– Periodically review research findings and revise
management plan accordingly

28. For virus management
• Continued interaction between scientists,
growers, and seed certification officials
– Potato Virus Control meeting held every spring
• Mostly USA researchers and seed certification officials
– Seed Potato Certification Section meeting held
every winter
• Canada and USA officials and researchers

29. • Previous to 2007, 95% of winter test plots
visually inspected
• Outbreak of PVY: one “problem” seed source
sold to many ware potato growers
– Karasev et al. 2008. Identification of Potato virus Y
strains associated with tuber damage during a
recent virus outbreak in potato in Idaho. Plant
Disease. 92:1371.
• CHANGE – ALL SEED LOTS ELISA TESTED
STARTING 2008
Change in Idaho to address PVY

30. ELISA Lab Testing

31. 2005 2006 2007 2008 2009 2010 2011 2012
% lots with PVY 27 61 60 61 51 40 50 38
% lots >2% PVY 15 30 27 20 16 8 19 14
0
10
20
30
40
50
60
70
80
90
100
% PVY in post‐harvest test
100% ELISA tested