b'Andys Advice:Know The Rules For Planting Back Non-Certified SeedPotato Tubers In North Dakota and MinnesotaBy Andy Robinson, Extension Potato Agronomist, NDSU/UMNcertifiedseedaredifferentforNorth SelectastoragebuildingthathasnotDakota and Minnesota and are found at used CIPC (chlorpropham) in the pastthe end of this article.three years. Residues of CIPC remain instorages in many places, and they canIf storing potato tubers for seed, there inhibitsproutsfromgrowingwhenare some considerations that should be planted in the field. Typical storage con-taken.Choosethebestpotatotubers ditionsforstoringseedshouldbethat have the lowest known virus rat- around 38 to 40 F with 90 to 95% rela-ings and other pathogens. This can be tive humidity. Cool storage conditionsdetermined from earlier seed generation will slow metabolism and help preventreports or from field inspections.This is sprouting, while high humidity will pre-importantbecausepotatovirusescan ventwaterlossandhelpkeeptuberslimityield,causetubernecrosis,and firm. If tubers are being stored for seedaffect overall tuber quality. Additionally, begin to sprout, there are some productsnon-certifiedseedlotswithhigher that can be used to burn off sprouts. BePotatoseedcertificationbeganinthe inoculum levels of virus planted back in sure to check with the label of any prod-early 1900s for the advancement of the certified seed growing areas can poten- ucts used for proper treatment rates andpotato industry. The focus was to con- tially threaten the seed supply for years thenecessarytimeintervalbetweentroldiseasesandvarietymixtures, tocome.Virusinthesenon-certified treatment and planting. improve varietal types and grant certifi- fields can be vectored by aphids to certi-cates based on varietal purity and clean- fiedseedfields,potentiallycausing North Dakota Century Code 4.1-55-05liness. This work continues today with rejection from certification, thus limit- https://www.legis.nd.gov/cencode/t04-improved practices, including laborato- ing future certified seed supply. Inspect 1c55.pdf#nameddest=4p1-55-05rytestingprocedures,morethorough tubers for diseases such as bacterial ringinspection and winter grow out testing. rot, late blight and other diseases that 4.1-55-05. Seed potatoes - Certification -Most states have a state agency that cer- couldcausecroplosses.Alaboratory Exception. tifies the seed and has specific rules and test is the best way to verify pathogenlaws pertaining to that state to ensure 1. a.A person may not plant seed pota-presence. Other tuber traits to that need toes unless the seed potatoes:the cleanliness of seed. The success of tobetakenintoconsiderationarethecommercialindustryislargely selecting tubers that are free from exces- (1)Have been certified by the seed com-dependent on seed quality.sivebruising,freezedamage,rotand missioner as meeting the standards ofotherproblemsthatwouldprevent this state;From time to time there are shortages in long-termstorageandqualityissues.the seed supply and some growers want (2)Have been certified by another stateThese damaged tubers will likely suffer or province having seed potatotoplantbacknon-certifiedseed.The quality loss in storage and could cause standardsthataredeterminedbytheobjective of this article is to cover these slow emergence and reduce plant estab- seed commissioner to meet or exceedrules for North Dakota and Minnesota lishment when planted the next grow- the standards of this state; orand discuss how to select the best seed ing season. tubers. The rules for planting back non- (3)At the request of the producer, were22 POTATO GROWER JANUARY 2020'