ABSTRACT
Lagarosiphon was first reported in New Zealand in the 1950s in the Hutt Valley, Wellington. By 1957 it had already reached nuisance proportions in Lake Rotorua (Howard-Williams and Davies, 1988) and by 1980 the weed was naturalized in a further ten regions. Today, Lagarosiphon is established throughout New Zealand and is still spreading, with recent new infestations in the South Island (e.g. Oreti River, Lake Wakatipu). A 2009 survey established that Lagarosiphon is present in 7.3 per cent of 344 surveyed lakes in New Zealand (de Winton et al, 2009).
