b'Andys Advice:Checklist OfPotato Emergence ProblemsEugenia Banks, Potato Specialist, Ontario Potato Board, Andy Robinson, Associate Professor and Extension PotatoAgronomist, North Dakota State University/University of Minnesota, Steven B. Johnson, Crops Specialist andExtension, Professor, University of Maine Cooperative Extensionfactorsinoptimizingcropemergence. This bacterium is found in all agricultur-Ideally,thesoiltemperatureandthe al soils and in surface water. Soft rot isseed temperature should be the same at favored by free water and high tempera-planting; ideally 50o to 55o F (10o to 13o tures.SoftrotbacteriaarepresentinC).Assoilswarm,sproutgrowth tuber lenticels penetrate tubers throughbecomes most rapid at 68o to 72o F (20o wounds or bruises. Fusarium infection ofto 22o C). Favorable soil moisture should seedcanpredisposeseedtobacterialbe in the range of 75 to 85% available decay. This can happen when seed pota-soil water. Seed treatments are available toes are left in a truck on warm days fortoreducetheincidenceoffungal 24 hours or longer or planted in warmpathogenssuchasFusarium, andwetsoil.Rottedtissueisbrown,Helminthosporium andRhizoctonia,but mushy,slimy,watersoaked,andsur-not for bacterial pathogens. roundedbyablackmargin.Infectedseed often has a foul odor and seed rotsSlowemergenceoftenresultsfrom quickly in the field leaving gaps in rows.plantinginnon-idealconditionsorAt times, potato growers may experience using lower quality seed. But sometimespoor emergence of potato plants. There a poor stand follows high quality seedare number of reasons why potato plants andperfectplantingconditions.Formay not emerge properly. This article is example,plantinggoodseedinawetintendedtoprovidealistofcommon soil, either hot or cold, favors bacterialproblemsthatcancausepoorpotato soft rot, which may result in poor stand.emergence and stand. Utilizing this list Or, planting good seed in ideal condi-can help growers more rapidly identify tions, a poor stand can occur because ofthe cause and improve management of herbicide carryover in the soil or herbi-the crop and subsequent crops. cideresiduesintheseed.Therearea Tubersoftrot.(EugeniaBanks,number of ways that potato emergence Ontario Potato Board) Planting healthy seed is one of the most can be affected. The following checklistimportant factors that allow growers to of common factors that occur before or Blackleg (Pectobacterium atrosepticum) produce a high-quality and high-yield- afterplantingthatreduceseedemer- This pathogen is primarily seed borne.ingpotatocrop.Certifiedseedshould gence.Rot starts at the stem end and extendsgive optimum emergence when handled intothetuber.Infectedfleshfirstand suberized properly especially keep- Checklist Of Problems That Cause appears cream-colored, but turns darker,ingtubersfreeofbruisesorinjuries Poor Potato Emergence/Stand greyishblackandmushywithtime.wounds. Optimum soil conditions will Secondary bacteria that invade affectedincrease the probability of a successful Seed Rot Caused By Bacterial/Fungal tubersgiveoffafishysmell.Plantingplant stand.Pathogens infectedtubersmayresultinseedrotTubersoftrot(Pectobacteriumcarotovo- andpre-emergenceorpost-emergenceSoiltemperatureandmoisturearekey rum subsp. carotovorum) stem rot called blackleg.18 POTATO GROWER MAY/JUNE 2021'