Before and after control of alien plant species in Kruger National Park, South Africa. Sunset Dam was heavily infested by Pistia stratiotes (A), which was effectively eliminated by a combination of biological and chemical control (B). Dense invasions of Lantana camara along the Sabie River (C) have required intensive mechanical and chemical control to clear (D). Populations of Opuntia stricta (E) have been effectively reduced to low numbers with biological control (F).