Principal source:
Compiler: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Review: Dr John Clayton. NIWA, National Institute of Water and Atmospheric Research. Hamilton, New Zealand.
Publication date: 2006-03-31
Recommended citation: Global Invasive Species Database (2024) Species profile: Hydrilla verticillata. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=272 on 07-10-2024.
\r\nPhysical: Harvesting and use of motorised boats is not recommended in partially infested lakes or where uncontamainated waterbodies occur nearby, because this can chop the plants and facilitate spread of shoot fragments (NIWA, 2003). In ponds and small lakes, water draw-downs, which expose and kill the plants, have been found effective. Weed mats in public access sites have been used to contain spread,and signage to increase public awareness are some of the containment methods adopted (NIWA, 2003).
\r\nChemical: Aquatic herbicides are effective at temporarily controlling the weed but do not kill the tubers, turions (overwintering structures that detach and geminate in the spring), and seeds. Some of the herbicides which have been used are Fluridone and endothall (dipotassium).
\r\nBiological: Biological controls include Chinese grass carp (Ctenopharyngodon idella), tuber-feeding weevils, and leaf-eating flies. Chinese grass carp have been found effective, but these fish are vegetative generalists, so they should be used with care so as not to destroy native aquatic vegetation. Tuber-feeding weevils and leaf-eating flies are still under evaluation for their effectiveness. The tuber-feeding weevil (Bagous affinis) only attacks the tuber when the plant is not submerged beneath the water. Leaf-eating flies, such as Hydrellia pakistanae , attack the weed by feeding on it as larva.(NIWA, 2003).
\r\nIntegrated management: An integrated approach of fish, mechanical, and manual methods to eradication has been found to achieve maximum success.