Blackleg

Blackleg is a common name used for two distinct plant and animal diseases, depending on the context.

In cattle and other ruminants, blackleg refers to an acute, often fatal infection caused primarily by Clostridium chauvoei. The bacterium forms hardy spores that persist in soil for years. Infection typically occurs when animals ingest or otherwise acquire spores that then settle in muscle tissue. Under favourable conditions, the bacteria produce toxins and gas, causing rapid muscle necrosis, swelling, and crepitation (a crackling sensation from gas in the tissue). Clinical signs include fever, lameness, reluctance to move, and sudden death. Diagnosis is based on clinical presentation, histopathology, and laboratory tests such as culture or PCR. Treatment is generally difficult and often unsuccessful once signs are evident; prevention is the mainstay, using multivalent clostridial vaccines (often combined with tetanus) given to young animals followed by boosters, along with good herd management to limit soil exposure, proper drainage, and prompt disposal of carcasses.

In plants, blackleg describes a bacterial disease of potatoes, commonly referred to as blackleg and soft rot. It is mainly caused by Pectobacterium carotovorum subsp. carotovorum and related Dickeya species. Infected plants show black, sunken lesions on stems and stolons, with tubers developing blackened tissue and soft rot. The disease spreads through infested soil, water, plant debris, contaminated tools, and seed potatoes. Management includes planting certified disease-free seed, crop rotation, thorough sanitation, avoiding wounding tubers, and careful handling during harvest and storage; minimizing soil moisture and drainage issues can reduce disease pressure.

The term blackleg therefore has both veterinary and plant-d pathology meanings, and context determines the applicable disease.