Evaluation of selected herbicides for the control of exotic submerged weeds in New Zealand: I. the use of endothall, triclopyr and dichlobenil

摘要

The aquatic herbicide diquat is the only product registered in New Zealand for controlling the submerged weeds lagarosiphon (Lagarosiphon major (Ridley) Wager), hornwort (in New Zealand) or coontail (Ceratophyllum demersum L), egeria ( Egeria densaPlanch), and hydrilla ( Hydrilla verticillata (Lf) Royle). However, diquat can be ineffective under some environmental conditions and it does not control certain submerged weeds. Greenhouse trials were conducted to evaluate the potential of the herbicides, endothall, triclopyr and dichlobenil to control the aforementioned target weeds and to evaluate impacts on the non-target native submerged species Potamogeton ochreatus Raoul, Potamogeton cheesemanii A. Benn, Myriophyllum triphyllum Orchard, Myriophyllum propinquun A. Cunn, Chara corallina Willd, Chara globularis Thuill, Nitella hookeri A. Br, Nitella leptostachys A. Br, and Nitella pseudo.flabellata A. Br when using these products. Endothall killed coontail, lagarosiphon and hydrilla and some species of Myriophyllum and Potamoyeton but not egeria or species of Chara or Nitella. Only transient growth effects were observed in target plants treated with triclopyr and dichlobenil.