Blackleg (potatoes)

Blackleg of Potato Wilt in Field

Blackleg is a bacterial disease that affects potato plants, caused primarily by the bacterium Pectobacterium atrosepticum. This disease is characterized by the blackening and rotting of the stem base, which can lead to significant crop losses. Blackleg is a major concern for potato growers worldwide due to its impact on both yield and quality.

Symptoms

The primary symptoms of blackleg include:

• Blackening of the stem base, which may extend upwards.
• Soft rot of the stem and tubers.
• Yellowing and wilting of the foliage.
• A foul odor emanating from the infected plant parts.

Causal Organism

The main causal organism of blackleg in potatoes is Pectobacterium atrosepticum. Other bacteria, such as Pectobacterium carotovorum and Dickeya dianthicola, can also cause similar symptoms and are sometimes involved in the disease complex.

Disease Cycle

Blackleg bacteria can survive in soil, infected plant debris, and seed potatoes. The disease is often introduced into a field through infected seed potatoes. The bacteria can spread through water, insects, and mechanical means such as contaminated equipment. Infection is favored by cool, wet conditions, which promote bacterial growth and spread.

Management

Effective management of blackleg involves several strategies:

• Use of certified disease-free seed potatoes.
• Crop rotation with non-host crops to reduce soil inoculum levels.
• Proper sanitation of equipment and storage facilities.
• Avoiding excessive irrigation and ensuring good drainage to reduce soil moisture levels.
• Application of appropriate bactericides and biocontrol agents.

Economic Impact

Blackleg can cause significant economic losses due to reduced yield and quality of potato tubers. Infected tubers are often unmarketable, leading to direct financial losses for growers. Additionally, the cost of managing the disease and implementing control measures can be substantial.

See Also

• Potato diseases
• Pectobacterium
• Soft rot
• Plant pathology