Anabaena fullebornii

Anabaena fullebornii is a genus of filamentous cyanobacteria that often acts as a biological stressor in irrigated agricultural systems. In the context of agronomy, it is categorized as a nuisance organism that causes significant water blooming, which disrupts the aquatic environment necessary for the healthy development of hydrophytic crops like rice.

The primary crop affected by this agent is rice, particularly in systems where water management is static. The presence of dense cyanobacterial mats negatively impacts the germination phase and early seedling development, creating a competitive environment for light and essential nutrients required for the initial stages of rice growth.

Symptoms of infestation include a vivid blue-green surface scum accompanied by a musty, earthy odor. As Anabaena fullebornii colonies thicken, they can wrap around stems and submerged leaves, blocking photosynthesis and causing physiological stress, which manifests as yellowing leaves and reduced tiller formation in the affected rice crop.

The spread of this organism is triggered by stagnant water, high ambient temperatures, and high nutrient concentrations, especially nitrates and phosphates, which promote rapid biomass accumulation. Sunlight intensity directly correlates with the rate of bloom formation, making fields exposed to full sun particularly susceptible during the growing season.

Effective management and protection strategies include the following:

• Maintaining active water circulation to prevent colony aggregation.
• Application of specialized algaecides to eliminate localized blooms.
• Optimizing fertilizer placement to minimize runoff into irrigation water.
• Implementing field drainage cycles to interrupt the growth cycle of the cyanobacteria.