Dickeya.
The Dickeya pathogen is in the seed. Contaminated plants that are able to emerge typically wilt and have black stems. The disease THRIVES in heat. Fungicides don't help and there are no resistant varieties available at this time. Some growers lost entire fields in 2015.
Read more here:
http://www.growingproduce.com/vegetables/dickeya-a-new-potato-disease
