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 ServicePhil Nolte, University of Idaho

9th Triennial African Potato Association Conference, Naivasha, KenyaJune 30 – July 3, 2013

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

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

Seed AreasCommercial Areas

USA Fall Potato Production Areas

50 %28%

5%

NPC, Statistical Yearbook 2009

5% all other areas

Foundation of Certification

• Grower enters eligible seed into program

• Field Inspections• Storage/Harvest Inspection • Post‐harvest inspection• Shipping point inspection

Tissue culture Greenhouse minitubers

Field production of seed

Inspections

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

Harvest

California Post‐Harvest Test

Shipping Point Inspection

Plant HealthCertificate

NORTH AMERICAN CERTIFIED SEED POTATO HEALTH CERTIFICATE - CROP YEAR 2002

Grower ImporterName Idaho Sunny Seed Inc.City, State/Prov. Seed Town, Idaho

Variety Russet Norkotah Quantity ShippedSize

Lot CertificationCertif ication # 52323551 Lot origination from tissue culture No Yes XSeed Class/Gen G3 Year micropropagated for planting 1998Certifying 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 o ther footnotes in 'Notes' below.

1998 1999 2000 2001 2002 Year of productionGreenhouse (insect excluding) & sterile soilField (note special measures[e.g. row covers] belo

59448990 50441890 51442390 52323551 Certif ication Number Number of years produced inID ID ID ID Certifying State field soil: 4

Summer Field Readings Field Inspection Post Harvest Readings1st 2nd 3rd Final Visual Location California0 0 0 % Leafroll 0

0.04 0 0 % Mosaic Sample No 4000 0 0 % Varietal 0 Plant Count 380

MixtureELISA test results for latent viruses

Less than 0 % Wilts % PVY 1Less 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 rmat io n is accurate to the best o f o ur kno wledge.

Jonathan Whitworth / Area Manager Program Official / Title

AgencyApproved f or use by t he Cert if icat ion Sect ion of t he Pot at o Associat ion of Amer ica - December 2001

Superior Greenhouses, Inc.

NORX

(208) 529-4358Idaho Crop Improvement Association Fax

11/12/02Date

(208) 522-9198Telephone

Lot info

Inspection results

Non‐quarantine pests

Pedigree

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

• USDA‐APHIS – Animal Plant Health Inspection Service

• USDA‐APHIS‐PPQ– Plant Protection and Quarantine

Federal Plant Protection Organization

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

State seed potato regulations

• Developed by Certification Agency• Approved by state authority (state government)

• Proposed changes to regulations in Idaho1. Proposed by growers or scientists2. Approved by grower advisory board3. Approved by scientists (for validity)4. Approved by state government

Political – Grower organization

• National Potato Council– Lobby: influence legislation

• U.S. Potato Board– Trade: promotion to USA and other countries

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)

Yellow spotting Stem necrosis Veinal necrosis Internal necrosis

Leaf drop Ring spots External necrosis

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  surveyO (66%)N (34%) 

2009 USA monitoring surveyO (44%)N (56%)

2011 USA  monitoring surveyO (22%)N (78%)

2012 USA monitoring surveyO (30%)N (70%)

FUTURE ??Predict problems with 

PTNRD

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

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

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

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

• 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 

ELISA Lab Testing

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

0102030405060708090100

% PVY in post‐harvest test

100% ELISA tested