PEI Potato Day 2017 Dickeya is the name of a group of bacteria. Various Dickeya species cause different plant diseases. Two species of Dickeya cause blackleg in potato. Dickeya blackleg is a more aggressive disease than blackleg caused by Pectobacterium atrosepticum. One of the blackleg-causing Dickeya species now occurs in Maine, and has been spread to other states. Blackleg is a potato disease with characteristic symptoms seed-piece decay black-pigmented soft rot of stems soft rot of tubers Blackleg is caused by several bacteria: . Pectobacterium atrosepticum . Pectobacterium brasiliense . Pectobacterium parmentieri (formerly wasabiae) . Dickeya dianthicola . Dickeya solani ATROSEPTICUM BLACKLEG DICKEYA BLACKLEG Usual cause of blackleg in Recently introduced into the Canada – in the past and United States, probably from currently Europe Favours lower temperatures Favours higher temperatures Symptoms: almost always Symptoms: sometimes clearly evident and visible on restricted to internal pith tissue stems of the stem Causes limited yield loss May cause serious disease loss ATROSEPTICUM DICKEYA Blackleg develops from bacteria that move from the seed tuber into the vascular tissue of the stem. These bacteria grow and multiple and produce soft-rotting Drawing from Potato Health Management. R.C. Rowe, ed. enzymes. APS Press Blackleg Disease Cycle The Seed Potato . They may look healthy and well BUT blackleg bacteria may be present in lenticels or stolon end vascular tissue During the growing season — from bacteria that spread from decaying seed pieces AND During harvesting, bin piling, sorting, etc. — whenever tubers come in contact with contaminated surfaces Clean seed ▪ High generation seed (fewer field generations) ▪ Know your seed source ▪ Good grower practices (your own and seed supplier) ▪ Laboratory tests (if unsure) Sanitation ▪ Bacteria are readily spread on equipment ▪ Blackleg bacteria are sensitive to common disinfectants ▪ Keep equipment clean ▪ Disinfect equipment between lots ▪ Clean up culls Roguing – yes, BUT be careful not to spread blackleg bacteria from infected plant. Survival in soil and water – yes, but for a limited time only (Dickeya probably a little more than P. atrosepticum). Spread by insects – theoretically yes, but not shown to be important. 1. Remain vigilant 2. Maintain good practices: clean seed & sanitation 3. If blackleg increases – get it lab tested (so you know what you are dealing with) .