Ecology, distribution and chemical control of Hydrocotyle ranunculoides inthe UK

Hydrocotyle ranunculoides L.f. is reported in this paper to be present at o nly 29 sites in the south east of England and in South Wales, in a wide ran ge of water body types, which are typically slow-flowing and eutrophic. The current infestation is likely to have originated from various introduction s from a single clone available at aquatic garden centres and nurseries in the U.K.. Experiments on the optimum chemical control method have shown tha t the plant is most susceptible to the herbicide 2,4-D amine applied at 4.2 3 kg ha(-1) active ingredient (a.i.). Initial observations suggest that the species is resistant to the herbicide glyphosate applied at 2.16 kg a.i. h a(-1). This resistance is postulated to be due to insufficient uptake of th e herbicide through the leaf cuticle.