Biology of invasive alien plants in Canada. 13. Stratiotes aloides L.

Abstract

The freshwater aquatic plant species Stratiotes aloides (water soldier) is native to Europe and central Asia, where it occurs in seasonally pleustonic or submergent populations. It has been imported into and cultivated in Canada as an ornamental plant. Recently it has been found escaped or persisting at five locations in south-central Ontario. A large population has established in the Trent River where it was likely present for several years prior to its discovery in 2008. The tendency of S. aloides to form dense floating mats can alter aquatic communities through competition and allelopathy, and is likely to inhibit navigation and recreational activities in the Great Lakes-St. Lawrence drainage system should it spread more widely in eastern North America. In Europe it is often abundant in ditches where it impedes flow and increases sedimentation. Moderate success at control has been achieved using herbicides (diquat) in the Trent River population, but manual removal has been inefficient. In spite of these control efforts, the plant is continuing to spread vegetatively downstream. An integrated management plan has been proposed to address its control by: (i) prevention of new introductions (pathway restriction); (ii) early detection and rapid response (newly established or found populations); and, (iii) eradication of known populations.