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Report2002

Hot Water Weed Control on Hard Surface Areas (Dissertation)

Hansson, David

Abstract

Interest has recently been focused on non-chemical weed control methods because of extensive restrictions in the use of herbicides. The overall aim of the thesis was to develop the hot water weed control method on hard surface areas and to study parameters that have an influence on the weed control effect and required energy dose. Experiments were carried out in laboratory, on arable fields and on hard surface areas. The test weed Sinapis alba L. (white mustard) was used in the laboratory and on arable fields, and naturally developed weeds in the experiments on hard surface areas. The effect of hot water can be described by dose-response curves similar to those of flame weeding and herbicides. The energy dose for a 90% reduction in plant weight in S. alba. in the 2-leaf stage was one third of the energy required for the same reduction in the 6-leaf stage. A longer lasting effect requires a higher energy dose. A 50% higher energy dose was needed to obtain a 90% reduction in weed cover that lasted for 15 days instead of 7 days. The required number of treatments on hard surface areas was similar to that for flame weeding. Six hot water treatments were needed during a vegetation season to obtain good weed control on an area similar to gravel embankments with a well-established natural weed flora. There was no significant difference in weed control effect at different air temperatures (7 °C and 18 °C). Wet plants, simulating rain before treatment, increased the required energy dose and drought decreased it. It was shown that, at the same energy dose level, the weed control effect was generally higher at higher water temperature. It was also found that there was a significant decrease in fresh weight when the drop size was increased. Prolonging the time of exposure by mounting an insulating sheet after the hot water applicator increased the weed control effect. Hot water has a potential for weed control, especially in urban areas where the use of herbicides is forbidden or restricted, but the method needs further development

Keywords

dose-response; effective dose; energy use; non-chemical weed control; temperature

Published in

Acta Universitatis Agriculturae Sueciae. Agraria
2002, number: 323
ISBN: 91-576-6156-1
Publisher: SLU Alnarp