Ivy-leaved duckweed

Ivy-leaved duckweed (Lemna trisulca) is a submerged aquatic perennial belonging to the Araceae family. Unlike common duckweed, which floats on the surface, this species forms intricate, branching chains of fronds that remain below the water level. This unique structure allows it to create dense underwater mats in slow-moving or stagnant water bodies.

This species is commonly found in irrigation canals, ponds, and rice paddies. In agricultural settings, it is considered a problematic weed because it can rapidly colonize water surfaces and submerged areas. It interferes with water flow and competes for essential nutrients, which are critical for the healthy growth of irrigated crops, particularly rice.

The biology of Lemna trisulca is characterized by high rates of vegetative propagation. Fronds break away to form new colonies, allowing the plant to carpet large areas within a single growing season. It is highly resilient, capable of overwintering at the bottom of water bodies in a dormant state, ensuring its persistence from year to year even in temperate climates.

The economic impact is primarily related to the blockage of irrigation and drainage infrastructure. By accumulating in hydraulic structures, the plant reduces water throughput and necessitates costly maintenance. In rice fields, the shading effect caused by dense mats of duckweed restricts the photosynthesis of young rice plants, which directly leads to reduced biomass and lower final grain yields.

Control measures require an integrated approach. Physical control, involving the mechanical removal of mats, remains the most immediate and eco-friendly solution for small-scale operations. In larger systems, chemical control using registered aquatic herbicides is possible, though it requires precise calibration to prevent off-target damage. Proper water management and periodic flushing of channels are also effective preventative practices.

• Mechanical removal of biomass using floating barriers or nets.
• Water level manipulation to disrupt growth cycles.
• Application of approved aquatic herbicides.
• Maintaining optimal water quality to discourage excess nutrient loading.