Ecology, distribution and chemical control of Hydrocotyle ranunculoides in the U.K.

Abstract

Hydrocotyle ranunculoides L.f. is reported in this paper to be present at only 29 sites in the south east of England and in South Wales, in a wide range of water body types, which are typically slow-flowing and eutrophic. The current infestation is likely to have originated from various introductions from a single clone available at aquatic garden centres and nurseries in the U.K. Experiments on the optimum chemical control method have shown that the plant is most susceptible to the herbicide 2,4-D amine applied at 4.23 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. ha^-1. This resistance is postulated to be due to insufficient uptake of the herbicide through the leaf cuticle.