Evaluating practical macrophyte control tools on small agricultural waterways in Canterbury, New Zealand. Issue 2 (3rd April 2019)

• Record Type: Journal Article
• Authors: Collins, Kathryn E.; Febria, Catherine M.; Warburton, Helen J.; Devlin, Hayley S.; Hogsden, Kristy L.; Goeller, Brandon C.; McIntosh, Angus R.; Harding, Jon S.
• Is Part Of: New Zealand journal of marine and freshwater research. Volume 53:Issue 2(2019)
• Page Start: 182
• Page End: 200
• Publication Date: 2019-04-03
• Subjects: Macrophyte control -- agricultural drains -- agricultural waterways -- plant management -- aquatic weeds -- Erythranthe guttata -- Nasturtium microphyllum; Marine biology -- New Zealand -- Periodicals; Freshwater biology -- New Zealand -- Periodicals; Freshwater biology; Marine biology; New Zealand; Periodicals; 578.77099305
• DOI: 10.1080/00288330.2018.1487454
• Languages: English
• ISSNs: 1175-8805

Abstract

ABSTRACT: Excessive macrophytes can cause significant problems in agricultural waterways requiring active management. Conventional control techniques can have a range of adverse effects. We investigated several control tools in two experiments: firstly, we tested eight treatments at a small-scale (2 m × 2 m). We found intensive hand weeding, weed mat and herbicide spraying to be effective treatments, reducing macrophyte cover to <5%. Hand weeding and weed mat immediately reduced cover, while dieback from herbicide took two months. Weed mat was a novel and effective control mechanism along stream banks. Secondly, we tested the impact of shading on macrophyte growth. Macrophyte growth was enhanced under partially shaded conditions, but with 80% effective shading over the entire channel, cover was reduced to 17%. Once treatments ceased, macrophytes grew back within 3–5 months. Long-term, control methods will require combinations of tools but will need to include optimal shading for the target species.