Evaluating practical macrophyte control tools on small agricultural waterways in Canterbury,New Zealand |
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| Authors: | Kathryn E Collins Catherine M Febria Helen J Warburton Hayley S Devlin Kristy L Hogsden Brandon C Goeller |
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| Institution: | School of Biological Sciences, University of Canterbury, Christchurch, New Zealand |
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| 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. |
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| Keywords: | Macrophyte control agricultural drains agricultural waterways plant management aquatic weeds Erythranthe guttata Nasturtium microphyllum |
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