Chrysophyceae

Being photosynthetic organisms, they thrive in environments where moisture and light coexist, effectively utilizing any available light sources to colonize surfaces rapidly.

They reproduce primarily via zoospores, which facilitate their spread through irrigation systems, drainage water, and farming equipment throughout the growing area.

These algae organize into colonies that form a slimy, dense biofilm on the surface of substrates, effectively sealing off the soil or growth media from the atmosphere.

Their presence is a biological indicator of an ecological imbalance in the greenhouse, often triggered by excessive nutrients in the growth medium.

The primary symptom is the emergence of a golden-brown or yellowish slimy layer covering the surface of the soil, rockwool, or other cultivation substrates.

Plants affected by these colonies show signs of growth inhibition, as the slime layer restricts root respiration and interferes with nutrient uptake.

Leaf chlorosis is frequently observed, as the root system, struggling with a lack of oxygen (hypoxia), becomes unable to supply sufficient minerals to the foliage.

In hydroponic setups, the nutrient solution becomes turbid, often accompanied by an unpleasant odor caused by the metabolic processes of the algal population.

Young seedlings often show wilting and root necrosis, which can be misidentified as fungal root rot if the surface algal growth is overlooked.

Excessive moisture on the substrate surface, combined with direct or artificial light, provides the necessary environment for the development of golden algae.

High levels of nutrients, particularly phosphorus and nitrogen, in the irrigation water serve as a primary food source, fueling rapid clonal expansion.

Temperature ranges from +18°C to +25°C are ideal for the metabolic activity and colonization speed of these organisms in greenhouse environments.

Poor ventilation and high relative humidity contribute to the formation of the stagnant microclimates that these algae require for optimal reproduction.

The use of overhead irrigation (sprinklers) facilitates the dissemination of zoospores to healthy parts of the greenhouse, spreading the infection rapidly.

The main harm caused by Chrysophyceae is the creation of a physical barrier that prevents gas exchange, leading to severe root hypoxia.

Golden algae compete aggressively with the primary crop for nutrients and growing space, often leading to nutrient deficiencies in the plant tissue.

Metabolic secretions from these algae can alter the pH of the growing medium, making it difficult for the plant to absorb essential microelements.

The algal mat acts as a breeding ground for secondary pathogens, including bacteria and fungi, which penetrate compromised root tissues, leading to systemic infections.

Financial losses are substantial due to reduced crop vigor, lower yields, and the high cost associated with disinfecting or replacing contaminated growing media.

Effective management begins with improving irrigation efficiency to ensure that the surface of the growing medium remains sufficiently dry to inhibit algal growth.

Using light-blocking covers or mulches on the surface of containers or rockwool slabs is one of the most successful ways to deny the algae the light they need to survive.

Regular sanitation of water tanks, drip lines, and trays using appropriate disinfectants helps to break the lifecycle of the zoospores.

Monitoring nutrient solution concentration is crucial, as avoiding excessive fertilizer levels effectively reduces the risk of algal blooms.

• Enhancing greenhouse airflow to reduce surface moisture.
• Physical cultivation of the top substrate layer to disrupt algal mats.
• Implementing bio-filters or specific algaecides in hydroponic systems.