anette phibbs, datcp, plant industry laboratory 4702 university ave, madison wi 53702

Anette Phibbs, DATCP, Plant Industry Laboratory 4702 University Ave, Madison WI 53702

Wisconsin Department of Agriculture, Trade and Consumer Protection

Wisconsin Pest Survey ReportWisconsin Pest Survey Reports s 20092009

http://pestsurvey.wi.gov/

Corky Ringspot SurveyCorky Ringspot Survey

Powdery Scab Survey Powdery Scab Survey


Wisconsin Pest Survey ReportWisconsin Pest Survey Report2009 Potato Survey for Corky Ringspot

Survey

Corky Ringspot Disease in the US • California,• Florida,• Idaho,• Washington• Oregon• Michigan• Minnesota• Wisconsin

(N. C. Gudmestad, I. Malik and J.S. Pasche, Plant Disease (2008) 92(8):1254)

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Tobacco Rattle Virus (TRV) and Nematodes

• TRV is transmitted by Stubby root nematodes

Trichodorus spp. and Paratrichodorus spp.

• These nematodes are present in Wisconsin.

• Hosts range is huge: potatoes, tomatoes, peppers, including many weeds, annuals and perennials (white & red clover, oats).

• Non-hosts are alfalfa, corn, barley, rye, wheat, carrots and pumpkin.

Nematodes in a 1.5ml tube.



Survey ¼ inch

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Astilbe Peony

Barrenwort

Coral bells

A. PhibbsHosta

Bleeding heart


Wisconsin Pest Survey ReportWisconsin Pest Survey ReportPerennials Infected with Tobacco Rattle Virus



Survey

Symptoms of CRS include necrotic brown rings in Ranger Russet.

Photo courtesy of Jim Crosslin, USDA-ARS, Prosser, WA

Brown corky flecks caused by CRS in Russet Burbank.

Photo courtesy of Jim Crosslin, USDA-ARS, Prosser WA

• Laboratory testing is performed at Plant Industry Laboratory. • We use nucleic acid assays, RT-PCR (reverse transcription

polymerase chain reaction).

References: D.J. Robinson, Journal or Virological Methods. 1992, 40, 57-66.” Detection of tobacco rattle virus by reverse transcription and polymerase chain reaction.”


Wisconsin Pest Survey Wisconsin Pest Survey Plant Industry Laboratory

• We checked all RNA extractions by simultaneously testing for a beta-tubulin reference gene and tobacco rattle virus RNA.

References: Mohan Kumar et al., J. Agric. Food Chem. 2007, 55, 1674-1678. “Extraction of RNA from Fresh, Frozen, and Lyophilized Tuber and Root Tissues.”



Survey Results• A total of 150 fields in 14

counties tested. • 19 Potato producers

participated.• 50 samples from seed

producing fields.• 100 from non-seed, fresh

vegetable or processing potatoes.

• All samples tested negative for Tobacco rattle virus, the virus that causes Corky ringspot disease in potatoes.

• Testing will continue in 2010.

Symptoms of Powdery Scab on Potato Tubers, Spongospora subterranea (Wallr.) Lagerh f.sp. subterranea Tomlinson

DATCP


Wisconsin Pest Survey ReportWisconsin Pest Survey Report2009 Potato Survey for Powdery Scab

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Common Scab, Streptomyces scabies, a bacterial disease



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Powdery Scab Biology

• Spongospora subterranea f.sp. subterranea is a soil borne slime fungus (Plasmodiophorales).

• Swimming spores (zoospores) infect roots, multiply in plant tissue and infect tubers.

• They form durable resting sporeballs (cystosori) on tuber skin and roots.

• Cystosori survive in soil for at least 6 years and survive passage thru animal digestive tract.

• Cystosori release more zoospores, go thru several infection cycles during a growing season.



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• Powdery scab infects potato, tomato, bell pepper, and Solanaceous weeds: Jimsonweed, groundcherry, nightshade, colt’s foot, wild tabacco and many more.

Powdery scab sporeball = cystosori.



Conditions Favoring Disease

• Cool temperate summers (Soil temperatures of 52F to 64F)

• Alternate periods of wet and dry soil, (Simulated by irrigation)

• Excess moisture during tuber set.

• Environmental conditions may be more important than amount of inoculum.

Pustules of Powdery scab on Red Norland Potato.

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Spread of Powdery scab

• Infected seed potatoes

• Contaminated soil, field to field movement of soil on equipment, tires, boots, …

• Manure or slurry

• Spore ball carrying dust in storage

• Grading lines



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Root Galls

Magnified Root Gall

Powdery scab symptoms on roots of potato.

Powdery scab produces root galls on a resistant potato varieties and re-infect soils.

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Powdery scab on potato “Molli”. A. Phibbs

A Brief History of Powdery scab in Wisconsin

• 2002 UW Clinic’s Brian Hudelson identifies Powdery scab on a Wisconsin potato sample for the first time.

• 2003-2004 DATCP conducts a soil survey of 68 fields in 10 counties.

• 6 fields in Adams, Oconto, Langlade and Waushara counties test positive.

Early Detection

• PCR detects any life stage of powdery scab (zoospores,

plasmodium) in any plant tissue.

• Examination under microscope and ELISA depend on presence of mature cystosori, formed in the tuber skin or root galls.



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Powdery scab sporeballs or cystosori under magnification.

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• Laboratory testing is performed at Plant Industry Laboratory.

• We use nucleic acid assays, PCR (polymerase chain reaction),

• Examine tuber skin with microscopes.

References: Qu et.al. (Plant Pathology (2001) 50: 420-426).



Department of Agriculture, Trade and Consumer Protection

Distribution of Powdery Scab in Wisconsin*

• Adams• Oconto• Pepin• Portage• Langlade• Waushara

* at least one field testing positive in a County.

Department of Agriculture, Trade and Consumer Protection

Survey Results• Total number of

potato samples processed in 2009: 150

• 19 Potato growers participated in 2009.

• Number of samples testing positive for Powdery scab: 17 (9%).

• 6 farms tested positive, with a total of 13 fields.

Potato Varieties that tested Positive for Powdery Scab in Wisconsin since 2002:

• Burbank (no tuber symptoms)• Gold Rush• (Dark) Red Norland• Norkotah• MegaChip• Molly• Ranger Russet• Russian Banana• Shepody• Silverton (no tuber symptoms)



Powdery Scab Symptoms on Shepody potato.

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Further Analysis of Powdery Scab• DNA sequenced from one sample from each farm that tested

positive.• All DNA sequences align 99-100% with Spongospora subterranea

subterranea type II.• Two genetically distinct groups (I and II).

Reference: Qu, X. & Christ B.J., American J of Potato Research (2004) 81:385-394.



The Problem

• Affects quality of potatoes (tuber skin blemishes and tumors)

• Affects crop productivity

• Affects storability

• Vectors Potato Mop Top Virus (PMTV)

• Creates infection opportunities for other diseases:

Late blight (Phytophthora infestans)

Pink rot (Phytophthora erthroseptica)

Dry rot (Fusarium spp.)

Black dot (Colletotrichum coccodes)



Phytosanitary GuidelinesPhytosanitary GuidelinesDiseases of Concern for Exports of Seed Potatoes Diseases of Concern for Exports of Seed Potatoes

to to Canada and MexicoCanada and Mexico

Viruses • Alfalfa Mosaic virus• Potato yellow dwarf virus• Potato yellowing virus• Potato mop top virus

(Mexico)• Potato spindle tuber viroid• PVYn• PVYntn• Tobacco rattle virus

(Mexico)

Source: USDA Excerpt 1/25/2010

Nematodes and Diseases• Potato Cyst Nematode (Globodera rostochiensis, G.

pallida)• Columbia Root-Knot Nematode

(Meloidogyne chitwoodii)• “Tropical” Root Rot Nematode

(Meloidogyne javanico)• Soybean cyst nematode

(Heterodera glycines)• Potato Wart

(Synchytrium endobioticum)• Bacterial ringrot

(Clavibacter michiganensis subsp. Sepedonicus

• Brown Rot (Rastonia solanacearum) race2

Wisconsin Rules• ATCP 156, Seed Potato Certification• ATCP 21 Plant Inspection and Pest Control

http://www.legis.state.wi.us/rsb/code/atcp/atcp021.pdf

• ATCP 21.14, Potato rot nematode• ATCP 21.14, Late BlightWisconsin Statues • Chapter 93 DATCP• Chapter 94 Plant Industry• http://www.legis.state.wi.us/rsb/stats.html


Potato Laws and RulesPotato Laws and Rules

2010 Survey • Testing for TRV and Powdery

scab will continue in 2010.• Please continue to participate! • Local contacts for sampling are:

Tim Leege (715) 623-3930 and

Sara Ott (715) 486-0429.


Wisconsin Pest Survey ReportWisconsin Pest Survey Report2009 Potato Survey for Corky Ringspot and

Powdery Scab

Don’t assume your fields are infected, have them tested.


Wisconsin Pest Survey Wisconsin Pest Survey http://pestsurvey.wi.gov/

Acknowledgements

• Kristyn Meyers• Rachel Leisso• Amanda Nelson• Sara Ott• Tim Leege• Jim Meyer

• USDA Cooperative Pest Survey Program and Specialty Crop Block Grant Program for funding.

For more information:

[email protected]

anette phibbs, datcp, plant industry laboratory 4702 university ave, madison wi 53702

Documents

corky ringspot survey

tobacco rattle virus

plant disease

potato tubers

potato producers

symptoms of powdery

phibbscommon scab

phibbstobacco rattle