Blackleg in potatoes is most commonly caused by Pectobacterium atrosepticum (older synonym: Erwinia carotovora subsp. astroseptica), a gram-negative, nonsporulating, facultative anaerobe that is also associated with soft rot of potatoes. The symptoms of potatoblackleg are unique and cannot be confused with the symptoms of soft rot, although they may co-exist.How to treat bacterial soft rot and blackleg in potatoes: Interwoven Management Strategies. Potatoblackleg is a common bacterial disease of potatoes, which causes black rotting at the stem base.What is potatoblackleg? Symptoms. Control. Biology. Healthy potato (left) and one infected with potatoblackleg (right). Image: RHS, Horticultural Science. Controlling Dickeya Blackleg of Potatoes. Potatoes with blackleg, once infected, cannot be treated with any chemical spray. This means that prevention and management through cultural practices are the best and really only ways to avoid losing a crop to the infection. Symptoms of potatoblackleg. The disease attacks the plants very early in the growing season, it’s not unusual for affected plants to show signs of the disease as early as mid June. Managing Blackleg of Potatoes. Andrew Plant— Plant Pathologist, Maine Potato Board.Dry potatoes before storage or shipping. References: 1. Adapted from: Al-Mughrabi, K. 2016. Dickeya: A new threat to potato production in North America. Spud Smart. Toyoshiro) with blacklegsymptoms were found in seed potato fields in Tokachi subprefecture of Hokkaido. Blackleg and stem rot are caused by various bacterial species belonging to the genera Pectobacterium and Dickeya (Czajkowski et al. Blacklegsymptoms: In some cases, bacterial soft rot can cause blacklegsymptoms. Treatment and Management of Bacterial Soft Rot in Potatoes. Cultural Controls. Remove infected tubers. Blacklegsymptoms increased with irrigation when the seed potatoes harbored any pathogenic bacteria, while symptoms of common scab increased under the driest conditions, reducing crop yields. The bacterium Dickeya solani causes a severe Blackleg like condition of potatoes. This is a relatively new pathogen, only being scientifically described in 2014. It can lead to up to 20% of seed potatoes being rejected in severely infected crops.
