Corky root

Corky root is a significant soil-borne disease caused by the bacterium Rhizorhapis suberifaciens. It is primarily known for its impact on lettuce crops, often causing major production losses in both field and greenhouse environments by compromising the plant's root system integrity.

The initial symptoms are characterized by yellow, water-soaked lesions on the roots. As the infection progresses, these lesions darken and expand, eventually causing the root tissue to become brittle, cracked, and corky in texture, which severely limits water and nutrient uptake.

The development of the pathogen is favored by warm soil temperatures, generally between 20°C and 28°C, and high nitrogen levels in the soil. The bacteria can persist in the soil for several years, making the site a long-term reservoir for potential future infections.

The impact of this disease is reflected in reduced crop vigor, stunted growth, and premature wilting during periods of heat stress. Severely infected plants often fail to reach marketable size, significantly reducing the overall yield and profitability of the affected area.

• Select and plant resistant lettuce cultivars.
• Rotate crops to minimize pathogen build-up in the soil.
• Use soil steam sterilization or solarization in greenhouses.
• Monitor and optimize soil nutrient levels, especially nitrogen.
• Implement strict sanitation measures to remove infected crop debris.