Last year a “new” potato disease was found in several states in the Northeast and a few in the Midwest. The bacterial disease looks at first like blackleg, caused by a different bacterium, but is much more aggressive and can cause severe losses. The disease is introduced on seed potatoes, and results in poor seedling emergence and rapid wilting in hot weather. The black stems tend not to be slimy and often do not have the rancid odor we normally associate with soft rot and blackleg caused by Pectobacterium. So far this year, Dickeya has been found in NJ, NY, DE, PA, MD, NC and VA on potatoes; in all cases seed potatoes came from Maine or New Brunswick, Canada. According to Rutgers University pathologist Andy Wyenandt, although the disease can cause 100% loss, USDA Animal and Plant Health Inspection Service (APHIS) has declared the pathogen Dickeya dianthicola non-reportable/non-actionable because it has been found in the US previously. Like most diseases caused by bacteria, management is mainly preventative, beginning with clean seed potatoes free of the pathogen. Maine certified seed potato growers are working to limit tolerances for blackleg in seed production fields. OH is one of many states that utilize Maine seed potatoes.
The OSU Vegetable Pathology Lab will test potato blackleg samples for Dickeya free of charge for Ohio growers. Samples can be dropped off at our lab on the OSU-OARDC Wooster campus, at OARDC Experiment Stations in Celeryville or Fremont, or mailed to us. Since samples will rot very quickly, we highly recommend they be shipped via overnight mail. Please follow instructions and use our sample submission form.