Brown algae

Brown algae (class Phaeophyceae) represent a significant concern in controlled-environment agriculture and hydroponic production. While primarily marine organisms, their presence in greenhouse irrigation systems is treated as a major biological nuisance that can severely compromise crop health and system infrastructure performance.

These organisms proliferate when spores infiltrate irrigation water, rapidly establishing colonies on the internal walls of supply lines, pump components, and the root zones of plants. Unlike typical plant pathogens, brown algae act as nutrient thieves and physical barriers, creating dense mats that impede essential oxygen exchange and nutrient uptake in hydroponically grown crops.

Various crops, including lettuce, basil, and greenhouse tomatoes, are highly susceptible to algae-related stress. The physical presence of algae on root surfaces leads to root asphyxiation, stunting, and reduced biomass production. Furthermore, the decay of algal mats creates an anaerobic environment that fosters the development of severe fungal diseases, including root rot caused by Pythium species.

The development of Phaeophyceae in artificial systems is driven by high levels of light penetration into nutrient reservoirs, elevated water temperatures (exceeding 22°C), and excessive nutrient availability, particularly phosphorus. These conditions favor rapid colonization, turning clear nutrient solutions into murky, slime-filled environments that are difficult to manage once fully established.

The economic impact of this issue includes reduced crop yields, increased maintenance costs for cleaning irrigation equipment, and the risk of catastrophic system failure due to clogged emitters. Effective management requires a combination of strict light exclusion and active sterilization strategies to ensure the integrity of the irrigation water throughout the growing cycle.

• Install opaque reservoirs and light-blocking covers for all water lines.
• Utilize ultraviolet (UV) sterilization units for continuous water treatment.
• Regularly flush irrigation systems with hydrogen peroxide to break down organic buildup.
• Implement strict filtration protocols to prevent spore entry into the system.
• Keep nutrient solution temperatures within the optimal range of 18–20°C.