Water Soldier

Background

Prior to its regulation in 2016, under Ontario’s Invasive Species Act, water soldier was sold commercially as a plant for use in ornamental water gardens and that is the likely source of the plants now found growing in the wild in Ontario. 

Water soldier can be easily distinguished from other aquatic plants by its leaf that has sharp spines along the edges. 

Water Soldier reproduces very quickly. It reproduces through its offsets, turions and clonal fragmentation for dispersal. The offsets act similar to those produced by the household spider plant and they look like smaller versions of the adult plant.

Water soldier is capable of reproducing without seeds through a process known as vegetative reproduction. New buds, that look like small versions of the mature plant, develop and detach to over-winter. The “parent plant” sinks to the bottom of the water body by November and overwinters.

Its abundant growth can alter wetland ecosystems by converting open water habitats into dense stands of vegetation, which can negatively affect the fish and wildlife that use these habitats.

Dense floating mats of Water soldier can interfere with recreational activities, such as boating, angling, and swimming. Caution should be exercised whenever handling the plant because of the sharp edges of the leaves.

The proposed approach to address water soldier has been developed, based on the guidance provided by the members of the Bay of Quinte – Water Soldier Working Group, and is also informed by the Prevention and Response Plan for Water Soldier in Ontario. The strategy focuses on three key elements:

• Environmental DNA surveillance of Bay of Quinte and Lake Ontario, with water samples collected by several partners agencies to be analyzed for the presence of Water soldier DNA by the Ministry’s genetics laboratory. This is to help direct monitoring efforts in the Bay of Quinte.
• Quinte Conservation performs aquatic vegetation surveys in 15 coastal wetlands in the Bay of Quinte which is already part of QC's routine monitoring program.
• Monitoring and mapping of known populations of Water soldier to inform control activities. This is through vegetation surveys. Based on the eDNA, external reports from the public and the results from the 2022 surveillance, water solider vegetation surveys are ongoing to determine population size and guide management decisions. The protocol utilizes a 50 x 50 metres grid to survey areas and the data at the points collected includes water depth, water soldier ranking value which indicates presence of Water Soldier, and the top three abundant aquatic plant species. 

Management options

Diver Assisted Suction Harvesting

Diver assisted suction harvesting is not readily available and it would not be ideal for the Bay of Quinte due to silty and muddy substrates.  

Herbicide Application

Herbicide applications have proved the most successful management control option in the Trent River. It is typically applied in the fall once the native vegetation has receded to prevent harm to native species of plants. 

Manual Removal

Manual removal of water soldier involves using hand-held devices (e.g., rake) to tackle individual plants and small groups of plants (generally between May and August). This has been ongoing for smaller populations.

Mechanical Harvester

Mechanical harvesting was proposed for 2023, however, access to a functioning harvester was not possible for the timeframe it was required. Mechanical Harvesting is better performed in the spring before the turions are produced by the water soldier to prevent spreading. It is effective to control mid-size populations in accessible locations with a near-by accessible boat launch, and areas to offload and dispose of large volumes of plant material.  

Shade Cloth Enclosure

The shade cloth enclosure is not ideal for the Bay of Quinte due to wave action and boat traffic.