1 **United States Department of Agriculture Animal and Plant Health Inspection Service**  **Plant Protection and Quarantine** 

# Importation, from Mexico into the United States, of **Potato, Solanum tuberosum**  **, Tubers for Consumption**

**Risk Management Docume**  **nt**

**February 16, 2012**

**United States Department of Agriculture Animal and Plant Health Inspection Service**  **Agency Contact: David**  **B. L amb** 2



### Introduction **:** The National Plant Protection Organization (NPPO) of Mexico has requested market access for the importation of potatoes for consumption , Solanum tuberosum L . , into the United States . A pathway- initiated risk assessment (PRA) was conducted by APHI S (USDA, 2011) . The PRA was prepared based on United States Department of Agriculture (USDA)’s Animal and Plant Health Inspection Service (APHI S) records of intercepted pests and scientific literature. The PRA document entitled , Importation, from Mexico into the United States, of Potato, Solanum tuberosum , Tubers Intended for Consumption , A Pathwa y -In itiated Commodity Risk A ssessment (USDA, 20 11 ) identified one bacteri um , four fungi , 2 insect s and one nematode that may follow the pathway

o f fresh potatoes for consumption from Mexico into the United States. **Bacteria** Ralstonia solanacearum R ace 3 biovar 2 (Smith) Yabuuchi et al . ( Burkholderiales: Ralstoniaceae ) **Fungi** Rosellinia bunodes (Berk. & Broome) Sacc. (Xylariales: Xylariaceae) Rosellinia pepo Pat. (Xylariales: Xylariaceae) Synchytrium endobioticum (Schilb.) Percival (Chy tridiales: Sy

nchi triaceae) Thecaphora solani (Thirum. & M. O’Brien) Mordue (Urocy stales: Glomosporiaceae) **Insects** Epicaerus cognatus Sharp (Coleoptera: Curculiondae) Copitarsia decolora (Guenée) (Lepidoptera: Noctuidae) **Nematodes** Nacobbus aberrans (Thorne) Thorne & All en (Nematoda: Pratylenchidae ) (The risk assessment also identified Globodera rostochiensis , golden cy st nematode, as a pest of quarantine significance that exists in Mexico, and determined that this pest is unlikely to follow the pathway only because it is under official control within Mexico. Therefore, this document recommends mitigations for Globodera rostochiensis , as well.) The bacterium Ralstonia solanacearum R ace 3 biovar 2 , the fungus Synchytrium endobioticum (Potato wart disease) and the nemat ode Nacobbus aberrans were rated **High** overall pest risk potential in the PRA. The fungi Rosellinia bunodes , R. pepo and Thecaphora solani and the insects Copitarsia decolara and Epicaerus cognatus were rated **Medium** overall pest risk potential in the PRA. Specific phy tosanitary measures beyond port of entry inspection are strongly recommended for pests with **High** pest risk potentials, and may be necessary

for pests with **Medium** pest risk potential (USDA, 2000) .3



### Risk **Management Measures :**  APHI S proposes to import fresh potato e s for consumption from Mexico using risk management measures equivalent to the management measures agreed for exportation of United S tates p otatoes for consumption to Mexico (USDA, 2010). Potatoes for consumption from Mexico may onl y be imported using all of the following risk management measures: 1. COMMERCIAL CONSI GNMENTS AND FOR CONSUMPTI ON ONLY . Potatoes from Mexico will be imported as commercial consignments only ; l imiting and labeling the end use to “consumption only . ” 2 . CE RTIFICATION PROGRAM/USE OF CERTIFIED SEED POTATO ES The potatoes must be produced by a grower who is registered within a certification program administered by

the NPPO of Mexico. At a minimum, the program must require the producer to use only seed that ha s been certified by the NPPO as free of Ralstonia solanacearum Race 3 biovar 2 , Rosellinia bunodes , Rosellinia pepo, Synchytrium endobioticum , and Thecaphora solani to produce the potatoes. It must also require the potatoes to be produced in an enclosed e nvironment, or alternatively , must require the field in which the potatoes are grown to be surveyed regularly

for quarantine pests and tested for Ralstonia solanacearum Race 3 biovar 2 at set intervals. 3 . WASHI

NG , FREEDOM OF SOI L, AND APPL IC ATI ON OF SPROUT I NHIBITOR Potatoes must be washed , free of soil and treated with a sprout inhibitor:

 Potatoes will be treated with a sprout inhibitor on the packing line two weeks after being harvested in accordance with label restrictions and correct usage of th e product.

 Potatoes in storage less than three months will be treated with sprout inhibitor in storage or on the packing line.

 Potatoes in storage for three to five months will be treated in storage and again on the packing line.

 Potatoes in storage for more than five months will be treated twice in storage and again on the packing line.

 Final application of sprout inhibitor will be done after the potatoes have been washed and soil was eliminated . The packer/shipper must provide the certifying official with credible documentation (e.g., grower declaration/records and packing shed records) that demonstrates that the potatoes have been correctly treated with sprout inhibitor for each required application.4

4 . POTA TOES PRODUCED I N NPPO OF MEXI CO - APPROVED F ACILIT IE S AND TRACEBACK OF POTATOES .  The NPPO of Mexico will approve the packing sheds used to pack potatoes for export to the United States and will assign unique numbers to each packing shed. This will allow consignments to be traced back to the packing shed and therefore to the grower, as necessary . This number must be shown on all consignment units (bag or box) and will be shown on the phy

tosanitary certificate. 5 . PHYTOSANI TARY I

NSPECTI ON AND CERTIFICATION STATING FREEDOM OF PESTS OF QUARANTI

NE CONC ERN The phy tosanitary inspections will be conducted and phy tosanitary certificates issued by the NPPO of Mexico .  C ontainers (i.e., boxes or bags in the consignment ) will be sampled using a biometric sampling plan at the packing shed and inspected for exter nal sy mptoms of the pests of quarantine concern to the United States ( Copitarsia decolora , Epicaerus cognatus , Nacobbus aberrans, Rosellinia bunodes, Rosellinia pepo and Thecaphora solani ).

 A portion of the potatoes from each sample will be cut and exami ned for internal sy mptoms /signs of Epicaerus cognatus , Nacobbus aberrans, Ralstonia solanacearum Race 3 biovar 2 , and Thecaphora solani .  The portion must then be sent to a laboratory that is approved by

the NPPO of Mexico for testing for Ralstonia solanac earum Race 3 biovar 2 .  Zero tolerance will be allowed for the pests of quarantine significance to the United S tates listed above .  P otatoes must show no signs of sprouting.

 Each phy

tosanitary certificate will bear the additional declaration stating : " This shipment does not come from an area of Mexico regulated by the NPPO of Mexico for Globodera rostochiensis , has been produced from certified seed free of Ralstonia solanacearum Race 3 , Rosellinia bunodes, Rosellinia pepo, Synch y tr i um endobioticum and T hecaptora solani , has been inspected for Copitarsia decolora, Epicaerus cognatus , Nacobbus aberrans Ralstonia solanacearum Race 3 biovar 2 , Rosellinia bunodes, Rosellinia pepo, Synchitrum endobioticum, and Thecap h ora solani, has been tested for Ralstonia s olanacearum Race 3 biovar 2 , and based on this inspection and testing, has been found free of those pests. “5

6 . SEAL IN G OF VEHI CL ES AT THE POI NT OF I NSPECTI ON All conveyances with potato consignment s will be sealed at the point of inspection and the sea l number will be noted on the phy tosanitary certificate. Seals may

not be broken in Mexico except as noted in Section 7 . 7 . BROKEN SEALS Actions taken when consignment s arrive at the border with broken seals are:

 If seals are broken enroute and the integrity of the load/ consignment has not been violated, the normal sampling and inspection regime will be applied.

 If the integrity

of the load is questioned because of broken pallet straps or missing or opened boxes , or if the consignment arrives at the b order with broken seal but no affidavit accompanies the consignment , APHI S will determine the phy tosanitary measure according to the Procedures specified in the corresponding work plan . 8 . DETECTI ON OF QUARANTI NE PESTS If the pests of quarantine concern to the United States are intercepted at the United States ports of entry , the consignment will be rejected and the NPPO of Mexico will trace back all interceptions to origin via the packing house number assigned. Should a second confirmed interception be attributed to a single packing facility , the NPPO of Mexico will investigate and take appropriate action mutually

agreed upon by the NPPO of Mexico and APHI S . Inthese cases:

 Should the NPPO of Mexico i nvestigation require the packing facility to identif y the suspect grower or growers, the packing facility will be required to do so. I f the packing facility cannot identify

the suspect grower, the packing facility will be suspended from the export program for the remainder of the season.

 Insuch cases wher e grower ide ntification is required by NPPO of Mexico and is provided by the packing facility , the grower will be required to identify the field where the intercepted infested/infected potatoes were produced. I f the grower is unable to do so, the grower wi ll be suspended from the export program for the remainder of the season.

 Where the grower can identify the field where the intercepted infested/infected potatoes were produced, the field will be suspended from the export program for the remainder of the s eason.6

9 . OPERATI ONAL WORK PLAN An operational work plan will be establised and agree d upon b etween APHI S and the NPPO of Mexico ( SENASI CA ) . 

### Evidence for **Removal of Pests of**  **Quarantine Concern from the Pathway**  **:** This risk management document has be en developed to minimize the risk of introduction of the following potato pests of quarantine concern from Mexico into the Unites States : Copitarsia decolora , Epicaerus cognatus , Globodera rostochiensis , Nacobbus aberrans, Ralstonia solanacearum R ace 3 bio var 2 , Rosellinia bunodes, Rosellinia pepo , Synchytrium endobioticum and Thecaphora solani . Li miting the importation of potatoes to commercial consignment s for consumption has two mitigati ng effects. First, r equiring commercial grade potatoes ensures a c ertain level of quality and cleanliness which results from commercial handling. This is a significant measure for pests that affect quality

or are associated with contaminants (e.g., soil). Second, l imiting and labeling the use to “consumption only” help s to prevent potatoes from being diverted to other purposes where they

are more likely

to come into contact with host material (i.e., growing plants) or for pests to be able to escape and establish in the United States . Potatoes from Mexico may not come f

rom areas of Mexico regulated by SENASI CA for G . rostochiensis . It is unlikely that producers in areas of Mexico regulated by SENASI CA for G . rostochiensis could meet the provisions of the certification program discussed above . Additionally , because G. rostochiensis is soil - borne, post - harvest cleaning would serve as an additional mitigation for the pest. However, because G. rostochiensis is under official control in Mexico, and a quarantine pest within the United States, in order to preclude the dissemi nation of the pest within both countries through the movement of infested po tatoes into the United States, APHI S considers such a prohibition to be warranted. Potat o es from Mexico must be produced only from certified seed potato e s. This measure is highl y effective in mitigating pest risk because it ensures the absence of specific pests at planting. Certified seed potato production is based on a generational process, under official control, in which a small quantity

of nuclear stock of a variety is incre ased to commercial quantities over a number of generations (Armstrong, 2003). During each generation, there is rigorous inspection and testing of the material to ensure that it is pest free . Certification programs require that seed potatoes be grown spec ifically for reproduction in a controlled environment to ensure the reduc ed potential for disease introduction. Genetic purity and disease control are maintained through the use of laboratory

testing, greenhouse techniques and limited generation productio n . Entry into a certification program means the field or lot of potatoes undergoes numerous inspections for nematodes, bacterial, viral, and fungal diseases, as well as trueness to ty pe , and adheres to strict tolerances . Certification tolerances for potato seed diseases are ty pically very low . A specific generation of seed can only be produced from an earlier, more disease - free generation (Mosley et al ., 2010) . The requirement that all potatoes to be exported to the United States must come from7

a certif ication program using certified seed potatoes ensures that pests and pathogens are eliminated from consignment s entirely , or kept at the lowest possible levels. All potatoes will be washed and brushed and treated with sprout inhibitor. Washing mitigates the pest risks posed by

soil contamination, and the application of a sprout inhibitor limits the use of potatoes for propagation (NAPPO, 2011 ; USDA, 2010 ) . Washing potato e s eliminates any adhering soil. Inspection of consignments and quality standards wi ll prevent soil from being exported with potatoes. Any findings of soil contamination would result in suspension of packinghouses from the export program. Depending on the particular compound used and the dosage applied, sprouting has been reported to be curtailed by about 30 - 100% (e.g., Thon, 1991; Afek et al ., 2000). Sprout inhibitors also may be effective in controlling some potato pests (e.g., Shelton & Wy

man, 1980). Research in Argentina (Cacace et al., 1995) using I sopropyl N - (3 - chlorophenyl) carb amate (Chloropropan) as a potato sprout inhibitor (inhibits sprout development by

interfering with cell division ) showed this sprout inhibitor was highly effective in reducing sprouting andweight losses due to sprouting , a s well as maintaining the external and cooking qualities after three months of application of Chloropropan with no negative characters such as peeling or internal sprouting. Because field inspection is a visual process, some plants may be questionable and need laboratory

verification. Mo st certification programs require some form of winter grow - out testing. For winter tests, a percentage of the tubers for each seed lot are planted and the resultant plants are visually

examined for pest/ disease sy mptoms (Mosley et al. , 2010). Phy tosani tary inspections consist of sampling and testing potato tubers during the growing season and after harvesting. Sampling and inspection of consignments at United States ports of entry is useful to verify

that phy tosanitary certification requirements have b een met and the consignment is generally

free of contaminants. The efficacy of this measure depends on the statistical level of sampling and the detection of the pests or articles of concern (e.g., soil). C ontainers (i.e., boxes or bags in the consignment ) will be sampled using a biometric sampling plan at the packing shed and inspected for external sy mptoms of the pests of quarantine concern to the United States. During the external inspection, the potatoes will be examined for lesions, galls, and necrot ic rings or spots on the surface of the tubers . The confidence level and percent infestion the inspection will detect can be established based on a hy pergeometric distribution. Consignments will be inspected and certified by the NPPO of Mexico or their d esignate to be free of pests of quarantine concern . A portion of the potatoes from each sample will be cut and examined for internal sy

mptoms of Epicaerus cognatus , Nacobbus aberrans , Ralstonia solanacearum Race 3 biovar 2 , and Thecaphora solani , and will also be tested for Ralstonia solanacearum Race 3 biovar 2 . This will also be the bas is of the Phy tosanitary certificate and the additional declaration . Consignments must be sealed at point of inspection. If any pest is found during inspection upon entry into the United States, then the field where the potatoes were produced will be suspended from the export program for the remainder of the growing season. I f the packinghouses or the grower cannot trace back the production to a field8

then the packingho use or the grower will be suspended for the remainder of the season. This ensures that any

problem fields (or growers or packinghouses) will be removed from the program until the cause of the failure can be eliminated. It will also maintain an incentive to ensure that records are kept so that traceback can occur. Sprout inhibitors are applied to all fresh potatoes prior to export to the Unite d States. These applications will limit the misuse of fresh potatoes and prevent plant growth and spread of any p athogens (NAPPO, 2011 ; USDA, 2010 ). Potatoes will be produced under an operational workplan agreed to by the NPPO of Mexico an d APHI S. This workplan can be revised at any time to deal with unexpected pest problems. Specific mitagations for pests/diseases of quarantine concern: (a) Bacteri um: Ralstonia solanacearum infect ed tubers exhibit conspicuo u s sy mptoms and may

include brown rot caused by

breakdown of infected vascular bundles ( EPPO, 2006 ) . The Ralstonia solanacearum of concern is Race 3, b iovar 2, which is a select agent o f quarantine concern for the the United States. Ralstonia solanacearum Race 3 b iovar 2 was eradicated from the United States. None of the interceptions from Mexico have ever been identified to Race. (b) Fungi: Synchytrium endobioti cum (Potato wart disease) causes dark brown warty cauliflower - like galls (corrugated surfaces) of infected tubers which decay to release golden - brown resting spores . Galls appear at stem bases , stolon tips and tuber eyes. Tubers may be d i sfigured or comp letely replace d by

galls. Tuber s in storage may develop galls after harvest . The fungus could be introduced via infected soil or plant tissues . L ocal spore dispersal was reported by water and wind a s a lim i ted pathway for distribution. Resting spores can rem a in viable for decades . Introduction into soil not only renders the crop unsu i table, but the soil itself cannot be use d for further crop production due to the longevity of the fungus (CABI . 2012d; Walker, 1983) . Rosellinia bunodes in duces wilt and death of the whole plant or individual stems . At the potato plant’s collar, the mycelial sheet is at first cream - white shading to purplish black, extending above the soil surface in moist conditions. The fungus p roduces thick and irregular knots on root surfaces, where black mycelial strands are firmly applied (Sivanesan & Holliday , 1972) . Rosellinia pepo (black root rot) spread s rapidly from organic debris left on crop surfaces after harvest . Removal and burning of infected material followed by change s in land use to cultivation of resistant crops is effective field management (CABI . 2012b). O n bulbs and roots, the grayish cobwe b - like mycel ia become black and coalesce into woo ll y or f elt - like mass es , usually

visible to the naked eye (Booth & Holliday , 1972; CABI . 2012b) . Plant a e rial sy mptoms may

be visible at the base of stems , with pale - gray to black myceli a (CABI . 2012b) . Thecaphora solani (potato smut) is transmited by infested tubers and is soil borne. Infections start in meristematic regions in young sh oo ts, the underground portion of stems and eventually in tubers . R esultant galls increase in size throughout the growing season ( Mordue, 1988) . Infested9

tubers are misshapen or have warty hard swellings on the surface; brown - black specks (spo re sori) 1 - 4 mm diameter can be seen in the flesh ( CABI . 2012 c). The fungi Rosellinia bunodes, Rosellinia pepo , Synchytrium endobioticum , and Thecaphora solani and the bacterium Ralstonia solanacearum Race 3 biovar 2 will be subject to detection during f ield certification inspections and tests and packinghouse inspections and tests . The NPPO of Mexico must certify consignment freedom from these fungi, specif i cally stat ing this in an ad d itional declaration . Potatoes will be cut , inspected , tested, and fo un d f ree of Ralstonia solanacearum Race 3 biovar 2 and Thecaphora solani , which will also be stated in the phy tosanitary certificate issue d by

the Mexican NPPO . Sampling of consignment s at port s of entry can be used to readily

detect visible disease sy

mpt oms in tubers (Zitter & Loria, 2010). Any producers’ fields and any associated packinghouses that ship infected tubers will be suspended from the program for the remainder of the season. (c) In sects: The two insect pests found by the PRA to follow the pathway of fresh potatoes from Mexico, Epicaerus cognatus and Copitarsia decolora , will be removed from the pathway by culling and inspection. The weevil Epicaerus cognatus is normally found only

in non - commercial potatoes because good agricultural practices eliminate this pest species. The weevil larvae are internal feeders in the tubers and can be identified by holes and waste (frass) ( USDA, 1959). If no exit hole is present, the feeding damage leaves the tuber soft. These sy mptoms of damage are readily d etected and any infested potatoes will be culled or detected by inspections. Potatoes will be cut for internal inspection to find Epicaerus cognatus . Copitarsia decolora is a L epidoptera that feeds in the larval stage on a wide variety of host plants. These pests are often found in weedy fields where they

may feed on almost any

host plant that is present. Damage to potatoes is primarily to the seed potatoes and the stalks of new plant growth (Munro, 1968). Damage caused by this insect to the part of the potato tuber that is above ground is very

obvious and will be removed during normal packing house culling processes to produce a quality

product. This damage would be very obvious and easily

detected during any phy tosanitary inspection, either by

the NPPO of Mexico or at the United States port of entry . (d) Nematodes: Nacobbus aberrans produces root galls mai n ly along the root axis and at the root tips with a beaded appearance (CABI . 2012 a) ; mature galls tend to be flat with a rough corky surface and bear many

lateral roots (Manzanilla L opez et al. , 2002). On heavily infected plants, the sy mptoms a bove ground include poor growth , stunting and yellowing of leaves. Nacobbus aberrans can be carried by potato tubers and in soil as well as in the root s of host plants (Jatala, 1979). The first step in detection is visual inspection for root or tuber knots. Nematodes have to be examined under a microscope to be different iated from other root - knot nematodes (CABI . 2012) .10

Contaminated soil is the most important means of spread of potato pests such as nematodes (Brodie, 1989). Potatoes imported from Mexico must be washed and free of soil to ensure freedom of nematodes as well as other pest s of quarantine concern. External and internal (cutting) inspection w ill help ensure that the nematode Nacobbus aberrans do es not follow the pathway of fresh potatoes for consumption from Mexico to the United Stares. 

### Conclusion **:** The phy tosanitary requirements described above for the importation of fresh potatoes for con sumption from Mexico into the United States include commercial consignments only , seed potato certification, washing and freedom of soil, external and internal inspections, treatment with sprout inhibitors to prevent misdirection of table stock to planting , traceback and suspension of problem packinghouses and production sites, sealed consignment s , and phy tosanitary certificate s with an additional declaration stating freedom of pests of concern . PPQ finds that when combined, these mitigations will ensure a pest - free sy stem for the production of potatoes for consumption because the initial propagules are uncontaminated (use of certified seed potatoes) , redundant safeguards keep the plants from becoming contaminated during production, harvest and transport , and the sprout ing capacity will be inhibit ed . If compliance with this program is achieved, then the potatoes produced in Mexico and imported into the United States will be protected from pest infestation and infection during the entire production process and phy tosanitary risks will be minimized. APHI S finds that the safeguards of this risk management document will result in the effective removal of the pests of concern i dentified in the pest ris k assessment (USDA, 2011) for the importation of fresh table stock potatoes for consumption from Mexico into the United States . 

### Author **s :**  Jos é R. Hern ández , Ph.D. Senior Risk Manager

– Plant Pathology Regulations Permits and Manuals Walter P. Gould , Ph.D. Senior Risk Manager

– Entomology Regulations Permits and Manuals Robert L . Griffin Director Plant Epidemiology and Risk Analy sis Laboratory Center of Plant Health Science and Technology Richard Zink, Ph.D. National Weeds Management Laboratory11

Center for Plant Health Science and Technology 

### References: Afek , U., J. Orenstein, and E. Nuriel. 2000. Using HPP (Hydrogen Peroxide Plus) to inhibit potato sprouting during storage. Am. J. Potato Res. 77(1): 63 - 65. Armstrong , K. 2003. Seed Potato Certification and Class X Seed. Irish Agric. Food Develop.Auth.; http://www.teagasc.ie/publications/2003/conferences/potato/paper01. Last access Oct. 2010 . Booth , C. and P. Holliday . 1972. Rosellinia pepo . C.M.I . Des cr. Patholog. Fungi Bact. 354:1 - 2. Brodie , B.B. 1989. Control of the golden nematode in the United States. Annual Review of Phy topathology

27:443 - 461. CABI . 2012 a . Nacobbus aberrans . Crop Protection Compendium. Last access Feb. 23, 2012. http://www.cabi.org/cpc/ CABI . 2012 b . Rosellinia pepo . Crop Protection Compendium. Last access Feb. 23, 2012. http://www.cabi.org/cpc/ CABI . 2012c . Synchytrium endobioticum . Crop Pr otection Compendium. Last access Feb. 23, 2012. http://www.cabi.org/cpc/ CABI . 2012 d. Thecaphora solani . Crop Protection Compendium. Last access Feb. 23, 2012. http://www.ca

bi.org/cpc/ Cacace , J.E., Weeder , D., Redriguez , J.C. , and Huarte , M. 1995. Ef f icacy of “Gro Stop Basis” s p rout inhibitor field application in Argentina. Potatoe Storage International 4(2):1 - 6. EPPO. 2006 . Ralstonia solanacearum R ace 3. Distribution Ma ps of Quarantine Pests for Europe. Paris: European and Mediterranean Plant Protection Organization. Jatala , P . 1979. Review of the false root - knot nematode (Nacobbus spp.). Research progress. International Potato Center. Report of the 2nd Planning Confer ence on the Developments in the Control of Nematode Pests of Potatoes, L ima, Peru, 13 - 17 November 1978. L ima, Peru: International Potato Center, 66 - 69. Manzanilla - Lo pez , R . H . , H arding , S . , and Evans , K . 1999. Morphometric study on twelve populations of Nacobbus aberrans (Thorne, 1935) Thorne & Allen, 1944 (Nematoda: Pratylenchidae) from Mexico and South America. Nematology , 1(5):477 - 49. Mordue , J. E.M. 1988 . Thecaphora solani . C .M.I . Descr. Patholog. Fungi Bact. 966:1 - 2.12

Mosley , A. , Vales, I . , McMorran, J. , and Yilma , S. 2010. Principles of Potato Production. http://oregonstate.edu/potatoes/CSS322WebNotes.html . L ast accessed 7 October, 2010. Munro, J.A. 1968. Insects affecting potatoes in Bolivia. Journal of Economic Entomology 61(3): 882. NAPPO. 2011. Mediation panel for trade between Mexico and the United States. Final report, September 23, 2011. No rth American Palnt Protection Organization. 58 pp. Shelton, A.M. , and J.A. Wy man. 1980. Postharvest potato tuberworm population levels in cull and volunteer potatoes, and means for control. J. Econ. Entomol. 73(1): 8 - 11. Sivanesan , A. , and P. Holliday . 1972. Rosellinia bunodes . C.M.I . Descr. Patholog. Fungi Bact. 351:1 - 2. Thon, A. 1991. Zum Einsatz hoherer Alkohole als Keimhemmungsmittel. Kartoffelbau 42(10): 417 - 419. USDA. 1959. Insects not known to occur in the United States: potato weevil ( Epica erus cognatus Sharp). USDA - ARS Plant Pest Control Division Cooperative Economic Insect Report 9(44): 971 - 972. USDA . 2000. Guidelines for Pathway- In itiated Pest Risk Assessments. Version 5.02. APHI S Plant Protection and Quarantine, Riverdale, Maryland. 31 pp. USDA. 2010. Exportation of United States Fresh Potatoes to Mexico. Risk management Document. United States department of Agriculture, Animal and Plant Health I nspection Service. 11 pp . USDA. 2011. Importation, from Mexico into the United States, o f Potato, Solanum tuberosum , Tubers Intended for Consumption, A Pathway- In itiated Commodity Risk Analy sis . USDA APHI S - PPQ Center for Plant Health Science and Technology , Plant Epidemiology

and Risk Analy sis L aboratory . 118 pp. Walker J. C. 1983 . Synchytrium endobioticum . C.M.I . Descr. Patholog. Fungi Bact. 755 :1 - 2. Zitter, T.A. , and R. L oria. 2010. Vegetable Crops. Detection of Potato Tuber Diseases & Defects. Information Bulletin 205 . Cooperative Extension, New York State, Cornell University http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_Detection.htm accessed Oct. 2010.