Diatom algae

Diatom algae (Bacillariophyceae) act as opportunistic organisms that can cause significant physiological stress to crops in greenhouse environments. While they are not traditional plant pathogens, their massive colonization of the soil surface or growth media creates a physical crust that severely limits gas exchange, negatively affecting the health and productivity of the cultivated plants.

The causative agents are various diatom species that thrive in environments characterized by high humidity, sufficient light, and an abundance of mineral nutrients. These algae possess siliceous cell walls, which, upon death, form a compact, impermeable layer on the surface of the soil or substrate, disrupting the soil's structure and preventing proper water infiltration during irrigation.

Crops most susceptible to these issues include greenhouse-grown vegetables, seedlings, and ornamentals. The problem is particularly acute in hydroponic systems and nursery containers where the combination of direct light and constant moisture provides the ideal environment for the proliferation of these organisms, which can eventually clog irrigation systems and compete for available minerals.

• Visual symptoms of algae buildup on the soil surface.
• Reduced seedling growth rates and general chlorosis.
• Presence of a dense, brownish-green crust covering the growing media.
• Increased incidence of root rot due to oxygen deficiency.

To mitigate the risks associated with diatom algae, growers should focus on cultural practices such as improving greenhouse ventilation to lower humidity levels and managing light exposure. Additionally, it is essential to ensure proper irrigation scheduling to prevent the surface from remaining constantly saturated. Using high-quality, sterile substrates and implementing regular cleaning schedules for irrigation equipment can significantly reduce the potential for algae outbreaks.