Slippery skin

Slippery skin is a significant bacterial disease affecting onion and garlic crops, primarily caused by the pathogen Burkholderia gladioli. This condition is characterized by the soft, watery decay of internal bulb scales, which can be devastating for both field production and post-harvest storage systems worldwide.

The primary symptom involves the softening and rotting of the inner fleshy scales of the bulb. Often, the outer skins of the onion remain intact and appear healthy, which makes early detection difficult. However, when the bulb is pressed or cut, the rotted, slimy tissue may slide out easily from the outer layers, often accompanied by a distinct foul odor.

Disease development is highly dependent on environmental conditions, particularly high soil moisture levels and warm temperatures. The bacteria typically gain entry into the plant through wounds caused by mechanical harvesting equipment, irrigation splash, or feeding damage from insect pests such as thrips or onion maggots.

The impact of this disease on agricultural profitability is severe. Because the rot is internal and often hidden, infected bulbs can enter the supply chain unnoticed, leading to rapid degradation of entire stored batches. Once the bacteria establish themselves in a storage facility, they can spread quickly if temperature and humidity levels are not strictly managed.

Effective management and prevention strategies are essential to minimize losses. Integrated pest management practices are recommended to protect the crop effectively:

• Ensuring rapid and thorough curing of bulbs after harvest to dry the neck tissues.
• Maintaining optimal storage conditions with consistent airflow and low humidity.
• Implementing crop rotation schedules to reduce pathogen buildup in the soil.
• Controlling insect populations that serve as vectors for bacterial entry.
• Sanitizing storage facilities and machinery to prevent cross-contamination.