Bacterial seedling rot of rice

The causative agent of the disease is Burkholderia plantarii, a gram-negative bacterium that primarily affects rice crops. This pathogen is known for its ability to produce phytotoxic metabolites, which significantly disrupt the development of young rice seedlings, often leading to total crop failure in heavily infested nursery beds or flooded fields.

The pathogen specifically targets Oryza sativa. Seedlings are most vulnerable during the germination stage and early establishment. Because the infection systemic, the bacterium colonizes the vascular tissues, leading to a breakdown of physiological processes, inhibited nutrient uptake, and eventual necrosis of the plant tissues.

The symptoms typically manifest as yellowing and wilting of the seedlings. As the disease progresses, the base of the stem exhibits soft rot, making the seedlings prone to lodging. Root development is severely restricted, and in advanced stages, the infected plant appears stunted or dies prematurely. Diagnostic observation often reveals bacterial ooze at the base of the stems under high humidity.

The spread of Burkholderia plantarii is highly dependent on environmental conditions, particularly moisture and temperature. The bacterium thrives in warm conditions, typically between 20°C and 30°C. Water acts as the primary vector, facilitating the movement of the pathogen through irrigation channels and across flooded rice paddies, which allows a single contaminated seed to impact a wider area.

Management of this bacterial disease requires a multifaceted approach. Farmers should prioritize the use of certified, pathogen-free seeds. Seed treatment, including hot water immersion or specific chemical disinfecting agents, is essential for reducing the initial inoculum. Maintaining proper field drainage and avoiding excessive nitrogen fertilization can also help reduce the susceptibility of the plants to the infection.