Achnanthes coarctata

Achnanthes coarctata is a species of diatom algae that, while not a pathogenic disease in the traditional sense, acts as an aggressive epiphyte in agricultural aquatic environments and hydroponic systems.

The organism is characterized by its ability to form dense biofilms on submerged roots, irrigation tubing, and tank walls. It utilizes dissolved minerals from the nutrient solution intended for the crops, thereby effectively stealing nutrition from the plants.

Crops most susceptible to colonization by this diatom are leafy greens and seedlings grown in deep-water culture or nutrient film technique (NFT) systems. Its presence is often a primary indicator of nutrient imbalance or excessive light penetration in the system.

Symptoms include a brownish, slime-like coating on the roots and surfaces, which hinders gas exchange. The restricted oxygen uptake often leads to stunted growth and increased susceptibility to opportunistic root rot pathogens.

Protection strategies focus on environmental management: preventing light exposure is the most effective way to eliminate these organisms. Additionally, regular sanitation of plumbing and water treatment using ozone or ultraviolet light are essential for long-term control.

• Light-proofing nutrient reservoirs
• UV water sterilization
• Periodic cleaning of hydroponic channels
• Nutrient management and pH balancing