Fragilaria

Fragilaria is a genus of diatom algae that, while being a natural aquatic organism, acts as a biological stressor in modern agricultural systems. In hydroponics and closed-loop irrigation, its proliferation is considered a systemic disruption that hinders plant development.

The organism acts as a colonizer of artificial environments. It develops primarily due to high levels of phosphorus and nitrogen in nutrient solutions, combined with exposure to light, creating dense mats of algae that interfere with standard irrigation protocols and water chemistry.

Plants affected by this phenomenon typically include greenhouse crops such as lettuce, herbs, and vine crops grown in recirculating systems. The presence of these algae is often an indicator of inadequate system hygiene rather than an airborne infection, impacting the root zone functionality.

Symptomatology involves the formation of brownish or yellowish sludge within irrigation pipes and on the root surface. This biological coating creates a physical barrier that limits nutrient uptake and gas exchange, leading to leaf chlorosis, stunted growth, and a general decline in the plant's health status.

Management strategies focus on preventing the algae from thriving in the first place. Essential measures include covering all reservoirs to block light, installing high-capacity UV-C water sterilizers, and maintaining a strict sanitation schedule to clean equipment and filter systems periodically.