De Boer, S. H. 2004. Blackleg of potato. The Plant Health Instructor. DOI:10.1094/PHI-I-2004-0712-01

DISEASE: Blackleg of potato

PATHOGEN: : Erwinia carotovora subsp. atroseptica (Synonym: Pectobacterium atrosepticum)

HOSTS: potato (Solanum tuberosum)

Author
Solke H. De Boer,
Centre for Animal and Plant Health, Charlottetown, PE, Canada

The blackened stem and wilted leaves are typical
of the potato blackleg disease. (Courtesy S.H. De Boer)

Introduction

Potatoes are grown world-wide and the crop is usually considered to be the fourth most important staple food source after wheat, rice, and corn. It is one of the few staple food crops that are vegetatively propagated. Vegetative propagation means that the potato crop is not grown from true seed but rather from asexually produced propagules or "seed potatoes." Potatoes are underground storage organs known as tubers and are attached to the mother plant by stolons. Potato tubers are not only harvested as a food source for fresh market and processed products, but are also used for planting a new crop. Seed potatoes only differ from eating and processing potatoes in that they are produced as a highly regulated crop to keep them free of potential pathogens and pests. True botanical seed tends to exclude many disease-causing microorganisms even if they are present in the parent plant. Vegetative propagules such as tubers, on the other hand, are often infected or contaminated by the pathogens associated with the parent plant. The bacterium that causes the blackleg disease of potato is one of the pathogens that is tuber-borne. The blackleg disease can cause severe economic losses to the potato crop. However, the occurrence of blackleg depends very much on the growing conditions, particularly temperature and rainfall after planting.