Aeromonas plant disease

Aeromonas plant disease refers to bacterial infections caused by the Aeromonas genus. While historically documented in aquaculture, these bacteria have emerged as significant opportunistic pathogens for greenhouse crops, hydroponic vegetables, and field crops grown in water-saturated soils, causing severe bacterial soft rot.

The pathogens are gram-negative, rod-shaped bacteria that thrive in aquatic environments and high-moisture conditions. They secrete extracellular enzymes such as cellulases and proteases, which break down plant cell walls and middle lamellae. This enzymatic activity leads to the rapid collapse of tissue structure, resulting in characteristic soft rot symptoms.

Susceptible crops include various greenhouse vegetables like tomatoes, cucumbers, peppers, and various leafy greens. The infection usually starts in the root system or at the base of the stem, often gaining entry through wounds caused by transplanting, soil insects, or nematode damage. Once systemic, the bacteria quickly clog the plant's vascular tissue.

The primary clinical signs of an Aeromonas infection are:

• Water-soaked, necrotic lesions on the roots and lower stems.
• Characteristic foul-smelling odor caused by the decomposition of plant tissue.
• Wilting of foliage despite adequate soil moisture levels.
• Blackening or browning of the root system and taproots.
• Rapid progression of tissue liquefaction, especially under high heat conditions.

The disease spread is accelerated by poor aeration, irrigation water contamination, and high ambient humidity. In hydroponic setups, the lack of sanitization can lead to widespread crop failure within days. The economic impact is high, as the infection can render entire batches of produce unmarketable due to the rapid onset of rot and secondary decay.

Management and prevention focus on strict hygiene and environmental control. Growers should ensure water quality by using sterilization methods like UV treatment or ozone in hydroponics. Implementing biological control agents, such as beneficial bacteria strains, can help suppress Aeromonas populations in the rhizosphere. Furthermore, maintaining proper soil drainage and minimizing mechanical plant damage are essential to prevent secondary infections.